JPS5933113B2 - Container and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a transparent box, a multilayer plastic molded container that has excellent resistance to delamination under impact such as dropping or vibration, and has an improved gas barrier against oxygen and the like, and a method for manufacturing the same.

In particular, the present invention includes an oriented bent resin that provides shape retention and strength to the container wall, and a layer of ethylene-vinyl alcohol copolymer that provides a gas barrier to the container wall, the copolymer layer having an uneven thickness. A multilayer plastic container in which effective molecular orientation is imparted to an oriented surrounding resin layer without causing defects such as cracks, pinholes, cracks, etc., and without causing delamination between both resin layers, and a method for producing the same. . Stretching Natsucho plastic resin at a relatively low temperature, that is, below or just above the melting point or softening point of the resin, increases stiffness and improves mechanical strength due to the orientation of polymer chains or crystals. It is widely known that improvements such as improvement of the transparent enclosure and improvement of the transparent enclosure occur.

Specifically, this technique is widely used for biaxially stretched films, filaments, stretched tapes, biaxially stretched props, stretch-molded cups, and the like. In the field of narrow-mouth and wide-mouth hollow plastic containers, for example, biaxially stretched blown vinylidene chloride resin bottles molded by the method described in Japanese Patent Publication No. 38-8583 have excellent gas-resistant properties. Since then, it has been widely used as a ketchup bottle, but it is rarely used today due to problems such as the generation of toxic gas when incinerated and the transfer of monomer into the contents.

Next, for example, Japanese Patent Publication No. 38-16245, Japanese Unexamined Patent Publication No. 4
Biaxially oriented polypropylene pottles, which are molded using the principle, method, and equipment described in Publication No. 6-3492, have excellent transparency, rigidity, and mechanical strength, so in the United States, polysalt-produced vinyl pottles have become popular. It is widely used as a replacement bottle for Jump type contents,
In Japan, it is partly used as a glass substitute for pharmaceutical bottles, such as Ringer's solution bottles. Also, Kunst
stOffeBd. 65. l975・H・10.666
The relatively low-temperature solid state pressure molded polypropylene wide-loop cup described in Section P is also attracting attention as a substitute for polyvinyl chloride cups. Furthermore, the biaxially oriented polyethylene teretarte bottle described in US Pat. No. 3,733,309 has completed its test market as a bottle for carbonated beverages in the United States and is attracting attention. The biaxially stretched blown vinylidene chloride bottle has the problem of monomer elution when it comes into direct contact with liquid, semi-liquid, or pasty food contents. Stretched polypropylene pots and solid-state pressure molded polypropylene cups have poor gas N resistance properties and cannot be practically applied to food products whose shelf life is sensitive to oxygen penetrating through the container wall.

Also, biaxially stretched blow polyethylene terephthalate bottles have relatively excellent gas barrier properties and excellent rigidity and transparency, but when left in an atmosphere at 60°C to 70°C for 3 to 5 minutes, The volumetric shrinkage rate is l~3%, the total height shrinkage rate is 0.4~0.8%, and the trunk diameter shrinkage rate is 0.
．． It exhibits a thermal shrinkage rate of 7 to 1.2%, and when left in an atmosphere of 80° C. for 1 minute, it deforms to an extent that it cannot be used for practical purposes, and cannot be used for hot filling or sterilizing sauces.

For the reasons mentioned above, the process of forming a thermoplastic resin into a parison with or without a bottom and then elongating the parison in its axial direction at a relatively low temperature, for example around the melting temperature of the resin. The steps of expanding the parison in the axial direction and in the orthogonal direction are carried out simultaneously or in this order (i.e., at the same time), thereby producing a biaxially stretched biaxially stretched blow-molded container, or as described above, for example, by melting the resin. In the case of biaxially stretched cup containers that are solid-state pressure formed from sheets at relatively low temperatures such as A multilayer container is required to withstand the demands of

Stretch molding of multilayer containers is already known. For example, in JP-A-48-32164, a multilayer parison comprising a polypropylene layer and an ethylene-vinyl alcohol copolymer layer is formed by a multilayer extrusion method, and this multilayer parison is formed by a multilayer extrusion method. The temperature of the parison is adjusted to 140 to 170°C under the temperature conditions above the secondary transition temperature of polypropylene and below the melting point, and the parison is mechanically stretched in the axial direction, and a positive pressure fluid is introduced into the stretched parison. A method of manufacturing a transparent container comprising blow molding by blowing is disclosed.

This invention imparts gas barrier properties to the container wall (by combining an ethylene-vinyl alcohol copolymer layer with a polypropylene layer), and provides transparency and impact resistance by imparting molecular orientation to the polypropylene layer. Although ethylene-vinyl gamma alcohol co-polymer has excellent gas barrier properties, it has low elongation and is difficult to stretch, resulting in pinholes and cracks during stretch forming. Oxygen permeation occurs easily through this portion, which causes a problem in that the storage stability of the contents is reduced compared to that of ordinary thermoformed containers.

In particular, ethylene-vinyl gamma alcohol copolymer and polypropylene hardly adhere to each other, and even when bonded with an adhesive, delamination is likely to occur under stretching conditions, and when both resin layers peel, the above-mentioned The occurrence of pinholes and cracks is particularly noticeable. Conventionally, when manufacturing multilayer containers by thermoforming, it is already known that an ethylene-vinyl alcohol copolymer layer and a polyolefin layer are bonded together via an unsaturated carboxylic acid grafted Natsucho plastic resin (
For example, see Japanese Unexamined Patent Publication No. 51-67384).

However, although the adhesive resin described above provides satisfactory interlayer adhesion under normal thermoforming conditions such as coextrusion or melt blow molding, it does not effectively impart molecular orientation to the polypropylene resin layer. Under stretch molding conditions, the interlayer adhesion is markedly reduced and tends to peel, and even when the ethylene-vinyl alcohol copolymer layer and polypropylene resin layer are maintained without peeling during stretch molding, ethylene - There is a tendency for the above-mentioned cracks or pinholes to occur in the vinyl alcohol copolymer layer, or for the copolymer layer to have a significant uneven thickness. The present inventors interposed an unsaturated carboxylic acid-modified resin between an ethylene-vinyl alcohol copolymer as an oxygen barrier resin and an alignment resin, and selected a combination of both resins that satisfies the formula. By doing so, stretch molding can be performed without causing delamination between the oxygen barrier resin layer and the oriented resin layer, and without generating cracks, pinholes, or uneven thickness in the oxygen barrier uniform resin layer. We found that the operation was easy.

Furthermore, the present inventors have achieved gas permeation resistance by orienting the oriented resin layer in the thin wall portion of the container so that at least one of its in-plane orientation coefficients (T, m) is 0.05 or more. It has been found that the properties are improved and, quite unexpectedly, the effect of significantly improving the impact peel resistance is achieved.

According to the present invention, in a container having a multilayer structure made of a plurality of types of thermoplastic resins, the container has at least one oxygen permeability coefficient of 5.5 x 10-12 cc·CTfL/d.
・S (generation)・? An ethylene-vinyl alcohol copolymer layer having an oxygen permeability coefficient of Hg (37°C) or less and having a vinyl alcohol content of 40 to 80 mol%, and the above-mentioned oxygen '\ which constitutes the inner layer and the outer layer with this layer sandwiched between them. It is composed of an oriented thermoplastic resin other than a thermoplastic resin, and both resin layers are bonded via an unsaturated carboxylic acid modified thermoplastic resin layer. In the formula, TB is an oxygen barrier property. TA represents the melting point or softening point (°C) of the oriented thermoplastic resin, and TA represents the melting point or softening point (°C) of the oriented thermoplastic resin.
At least one layer made of an oriented thermoplastic resin has at least one one-dimensional orientation coefficient (T, m) of 0.05 or more in the thinnest part of the container. Provided is a container with excellent oxygen barrier properties and impact peeling resistance, which is characterized by molecular orientation such that

According to the present invention, the oxygen permeability coefficient is 5.5×10−
At least one layer consisting of an ethylene-vinyl alcohol copolymer having a vinyl alcohol content of 40 to 80 mol% and having a vinyl alcohol content of 12CC-CTrL/~・s珈、儂Hg (37°C) or less, and this layer sandwiched therebetween. and an oriented thermoplastic resin layer other than the above-mentioned oxygen barrier resin constituting the inner layer and the outer layer, and both resin layers are bonded via an unsaturated carboxylic acid-modified thermoplastic resin layer. A parison or sheet is molded by simultaneous melt extrusion: where both resins are expressed by the following formula, where TB represents the melting point or softening point (°C) of the oxygen barrier thermoplastic resin, and TA represents the orientation. The parison or sheet is selected so as to satisfy the melting point or softening point (°C) of the plastic resin; At a molding temperature (Trrl) that satisfies
There is provided a method for producing a container with excellent oxygen barrier properties and impact peeling resistance, which is characterized by forming the container into the shape of the container under the conditions that cause the above-mentioned molecular orientation.

The present invention will be explained in detail below.

In the present invention, the oriented resin layer is used to provide the container with necessary shape retention, strength, etc.
On the other hand, the ethylene-vinyl gamma alcohol copolymer layer (hereinafter sometimes simply referred to as the pariah layer) allows gas
It is used to improve the storage stability of the contents by adding a layer of resin to the container.In order to reduce the weight of this container and improve transparency, rigidity, impact resistance, etc., an oriented resin layer is added. It is necessary to orient the molecules.

The present invention provides for the production of the above-mentioned molecularly oriented multilayer container.
In order to prevent delamination during stretch molding, the oriented resin layer and the barrier layer are bonded via an unsaturated carboxylic acid-modified thermoplastic resin (hereinafter sometimes simply referred to as acid-modified resin); Melting point or softening point (TA
) and the melting point or softening point (TB) of the barrier layer resin must be selected so as to satisfy the above formula (1).

That is, even if one of these requirements is lacking, delamination between the two resin layers will occur during stretch molding.
First, an ethylene-vinyl alcohol copolymer shows almost no adhesiveness to an oriented resin such as polypropylene, and therefore, when an acid-modified resin is not used, delamination occurs during molding.

Furthermore, in general, when a parison or sheet having a multilayer structure is subjected to stretch forming or solid state pressure forming, the peel strength between the layers is significantly reduced.

The reason for this is that unless each layer is made of chemically and physically identical thermoplastic resin, each layer will respond differently to an external force or force, that is, each layer will have different viscoelastic properties. It is thought that different stresses or strains are generated at the interlayer interfaces, resulting in a decrease in adhesive strength. This phenomenon is remarkable in the combination of ethylene-vinyl gamma alcohol copolymer and oriented resin, and under normal thermoforming conditions,
Even when an acid-modified resin exhibiting satisfactory adhesion between the copolymer and the alignment resin is interposed between the copolymer and the oriented resin, significant delamination occurs during stretch molding. However, when such delamination occurs, it becomes difficult to stretch the ethylene-vinyl alcohol copolymer, causing cracks and pinholes in the copolymer layer, and in severe cases, even rupture of the layer itself. arise. In the present invention, an acid-modified resin layer C is interposed between an oriented resin layer A and a barrier layer B, and
The above formula (1) is used as the oriented resin A and the barrier layer resin B.
The first feature is that by using a material that satisfies the following, different stresses or strains are prevented from being generated at the interlayer interface during molding, and delamination during molding is prevented.

The selection of the melting points of both resin layers and the combination of this with the use of the acid-modified resin are critical, as described in Section 3.5.8 below.
This becomes clear by referring to Table 10. To further explain this point, the melting point or softening point (T) of the barrier resin is the B melting point or softening point (TA) of the alignment resin.
If the temperature is 35°C or more lower than the above temperature, the barrier resin will be in a completely molten state under the container molding conditions that give the degree of orientation described below, and the barrier resin layer will be significantly uneven depending on the temperature distribution of the parison or sheet during molding. Due to the heat generation phenomenon caused by the solidification or crystallization of the barrier resin during the cooling stage after molding, stress or distortion may occur at the bonded interface, or the transparency of the stretched layers other than the barrier resin layer may be significantly reduced. I knew what to do.

Furthermore, the melting point or softening point (TB
) is 35°C below the melting point or softening point (TA) of the oriented resin.
If the degree of orientation is higher than that, the barrier resin will be in a viscoelastically relatively hard state under the container molding conditions that give the above-mentioned degree of orientation, causing cracks and pinholes in the layer itself, and High stress is generated at the interface between the resin layer and other adjacent resin layers, resulting in a significant decrease in the interlayer adhesion strength of the final molded container. As mentioned above, in order to prevent breakage, pinholes, cracks, etc. during stretch molding of the ethylene-vinyl alcohol copolymer, it is necessary to prevent peeling from the oriented resin layer. Although this is a requirement, it is also important that the copolymer layer B has a structure in which the inner and outer layers of the oriented resin A are sandwiched together.

That is, the copolymer layer is sandwiched from both sides by easily stretchable oriented resin layers, and by adhering to these layers, stretch molding becomes possible without the above-mentioned drawbacks. Furthermore, the above formula (
1TB-TA] within 35℃, especially 3
By setting the temperature within 0°C, most preferably within 10°C,
Conditions for molecular orientation of the oriented resin layer A and ethylene-
It becomes possible to match the conditions under which stretching of the vinyl alcohol copolymer occurs. In the present invention, at least one of the two-dimensional orientation coefficients (T, m) of the thinnest part of at least one oriented resin layer of the final molded container is 0.0.
It is important to provide a molecular orientation of 5 or more, especially 0.1 or more in terms of transparency, gas barrier properties, and impact delamination resistance.

In this specification, the two-dimensional orientation coefficient (T, m) is
For example, as described in Yasunori Nishijima; Polymers, VOtl 5, Taki 175, page 868 (Published by the Society of Polymer Science and Technology, 1966), the optical anisotropy of fluorescent molecules is utilized to create a thermoplastic resin. The degree of orientation and orientation form of molecular orientation due to solid deformation of a certain polymer, or during flow in a solution or solvent body, can be obtained from a method for quantitatively determining the degree of orientation and orientation of a certain polymer. Considering the two-dimensional orientation within the wall surface of the final molded container according to the invention, the degree of two-dimensional orientation is expressed by the following formula: , 〃 indicates that the vibration direction of the incident polarized light and the photometric polarization direction are parallel, and ω indicates the rotation angle of the sample with respect to the vibration direction of the polarized light.

K is the maximum excitation probability when the vibration direction of the excited fluorescence is parallel to the sample molecular axis, and φ is the molecular fluorescence yield. t is the proportion of molecules oriented in one arbitrary direction within the wall surface of the final molded container, m is the proportion of molecules oriented in a direction perpendicular to t, and n is the proportion of non-oriented molecules in the plane, and L + m + n = 1. be.

] can be expressed quantitatively.

If molecular orientation is given to oriented resin such as polypropylene,
It is a well-known fact that transparency, rigidity, and impact resistance are improved.

However, in the present invention, a transparent top soil with improved gas barrier properties can be obtained in the form of a multilayer structure with an ethylene-vinyl alcohol copolymer, and this fact is noteworthy. That is, the oriented resin layer and the ethylene
In stretch-molded containers where the vinyl alcohol copolymer layer has peeled off or where pinholes, cracks, etc. is rather reduced compared to a thermoformed container without orientation. On the other hand, in the present invention, T,
By providing a molecular orientation in which at least one of m is 0.05 or more, particularly 0.1 or more, a remarkable improvement in transparency and an improvement in gas barrier properties are brought about. This fact is related to the fact that the transparency of the oriented resin layer is improved by molecular orientation, and as shown in the example below, the transparency of the ethylene-vinyl alcohol copolymer layer is also improved by molecular orientation. be.

Furthermore, since the oxygen permeability coefficient of molecularly oriented polypropylene is about two orders of magnitude higher than that of ethylene-vinyl alcohol copolymer, the improvement in gas barrier properties also depends on the ethylene-vinyl alcohol copolymer layer itself. This seems to be due to molecular orientation. Furthermore, the multilayer container of the present invention has the unexpected effect of preventing delamination when subjected to impact such as vibration and dropping.

In other words, in this type of multilayer structure, the adhesive strength significantly decreases due to molecular orientation due to stretching, but contrary to this tendency, when the degree of molecular orientation increases, the adhesive strength decreases when the above-mentioned impact is applied. The tendency for delamination between the layers is significantly reduced. The reason for this is thought to be that the impact resistance to delamination is improved due to the wedge effect caused by the alignment molecules of the alignment resin and barrier resin. In this specification, the melting point (Me
ltingPOint) is, for example, LeOMande
Written by lkern0CRYSTALLIZATI0N0FP
0LYMERS0(MCGraW-HillBOOkC
Ornpany (1964), it is defined as the thermodynamic first-order dislocation point where the crystalline phase of a crystalline or semi-crystalline polymer melts, and is usually analyzed by differential thermal analysis or specific heat-temperature curve method. It can be easily determined by methods such as , polarized light microscopy, X-ray diffraction, and infrared absorption spectroscopy.

Furthermore, in this specification, softening point temperature (SOftning
POintTerrlperature) corresponds to the glass transition temperature, which is the thermodynamic second-order transition point described in, for example, the Physics of Polymers 1 edited by the Physical Society of Japan (published by Asakura Shoten, 1963), and is the temperature at which polymers soften. At the starting temperature, specific heat (or specific volume) - temperature curve method, differential thermal analysis method, industrial test method is ASTM D648-56ASTMD1525-
58T)) It can be easily determined using the ASTM D569-48 method.

The melting point (TB) of the ethylene-vinyl alcohol copolymer depends on the content of hydroxyl groups and therefore of vinyl alcohol units.

More specifically, the ethylene-vinyl alcohol copolymer is disclosed in US Pat. Nos. 3,183,203 and 341.
As described in No. 9654, a copolymer of ethylene or a major part of ethylene, a small amount of other olefins such as propylene, and a vinyl ester of a lower fatty acid such as vinyl formate, vinyl acetate, or vinyl pionate. , especially by saponifying an ethylene monovinyl acetate copolymer.

The melting point (TB) and ethylene molar content (%) of this ethylene-vinyl alcohol copolymer were determined by differential thermal analysis.
) is known to follow the following equation. In the above formula, TB is the melting point of an ethylene-vinyl alcohol copolymer containing 40 to 80% of ethylene, and X is the mole of vinyl alcohol content. Table 1 shows the oxygen permeability coefficient (
PO2, CC-? /d・s(i)・? Hg).

As the oriented thermoplastic resin A, it is desirable to use polypropylene. In addition to isotactic homopolypropylene, polypropylene has an ethylene content of 1 to 20 moles. A crystalline propylene-ethylene copolymer can be used. In addition, as the oriented resin A, polyethylene, polymethyl methacrylate, polystyrene, polycarbonate, polyacetal, etc. can be used as the final molding resin, although the effect of improving transparency by biaxial stretching molding and solid-phase pressure molding is smaller than that of the polypropylene. Blends of the above resins may also be used within a range that does not impair the physical properties of the container, particularly transparency. As the acid-modified resin C, a known unsaturated carboxylic acid-modified thermoplastic resin such as polypropylene modified with an unsaturated carboxylic acid such as maleic anhydride is used.

These resin layers have a multilayer structure in which the barrier layer B is sandwiched between the inner layer and the outer layer of the oriented resin A, and both resin layers are bonded via the acid-modified resin C.

The layer configurations suitably used in the present invention are, in order of preference, symmetrical five layers (A/C/B/C/A), symmetrical seven layers (A/A'/
C/B/C/A'/A), asymmetric five-layer (A/C/B/C
/A') etc.

Further, in the multilayer structure described above, the barrier resin layer B preferably accounts for 0.2 to 50%, particularly 2 to 20%, of the total thickness of the final molded container.

In addition, each of the resin layers described above is formed by molding a multilayered parison or sheet having a combination of the resin layers described above by simultaneous melt extrusion. Tm represents the molding temperature (°C).

It can be produced by any method known per se, except that it is molded at a temperature that satisfies the above conditions and under conditions that cause orientation of the oriented thermoplastic resin at least in the thinnest part of the container.

For example, parisons used in biaxial stretch blow molding can be manufactured by any means such as extrusion or injection molding. For example, a parison is formed using the conditions and means described in detail in Japanese Patent Application No. 50-149564, and then by a stretch-blowing manufacturing method, which is also an example of Japanese Patent Application No. 50-149564. The containers of the invention are molded. Further, for example, a sheet used for solid phase pressure forming can be manufactured by any means such as T-die forming. For example, a sheet is formed using the conditions and means described in detail in Japanese Patent Application No. 51-57192, and then
The container of the present invention is formed by a plug-assisted vacuum forming method as exemplified in the specification of No. 1-57192. The effect of biaxial stretching from a multilayer parison to a bottle, or from a multilayer sheet to a cup, varies markedly depending on the stretching temperature, stretching speed, and type of resin. , m), at least one of which is 0.05 or more;
In particular, if it is 0.1 or more, it can be said that the stretching orientation imparts effects such as improved transparency and rigidity to the final molded container.

For this reason, it is generally desirable that the stretching ratio of the parison or sheet be in the range of 1.1 to 20 times, particularly 1.5 to 5 times.

The stretching speed when molding a container from a parison or sheet varies depending on the type of resin, and may be within a speed range that produces the above-mentioned stretching effect on the molded container.
Special 1 1070/Mm to 6000000%/Mi! t
It is desirable to be within the range of . 1Tn]-TBl is 30℃
If it exceeds, it becomes difficult to obtain the container targeted by the present invention.

That is, if Tnl is lower than TB by more than 30°C, cracks or pinholes will occur in the ethylene-vinyl alcohol copolymer layer as shown in Table 8, resulting in a significant decrease in oxygen permeability and impact resistance. On the other hand, if TIn is higher than TB by more than 30° C., the stretch-molding operation itself becomes difficult. Furthermore, in terms of transparency, oxygen resistance, and impact delamination resistance, the molding temperature (
Trll) is preferably set to a temperature that does not substantially melt the barrier resin B, that is, a temperature that causes the barrier resin B to undergo molecular orientation upon stretching. Molded container Polypropylene (B)'x that satisfies the conditions mentioned above
A multilayer parison or sheet consisting of a rear layer and (C) a modified resin adhesive layer↓? Containers subjected to biaxial stretch blowing or solid phase pressure forming have excellent transparency, rigidity, and gas resistance, and are less prone to delamination problems even under impact.

Furthermore, due to the stretching effect, the container can be made thinner and lighter, and the amount of resin used can be significantly reduced. Although the molded container of the present invention differs depending on its use, it is generally 0.01 to 5 dt/9, particularly 0.05 to 2 dt/9.
It is manufactured with a basis weight (volume per unit g of resin) of dt/9, and the thickness of the container wall is 0.02 to 1 mm1, especially 0.0
It can range from 8 to 0.8 mm, and within these ranges the desired combination of gas barrier properties, stiffness, and transparency can be achieved.

The container of the present invention can be used for liquid or pasty foods and beverages,
For example, alcoholic beverages including beer and other low-malt beer, sake, fruit drinks such as shochu and grape wine, and various cocktails such as Jinfu's; various carbonated drinks including cola, cider, plain soda, etc.; lemon juice Fruit juice drinks, including straight juices such as , orange juice, plum juice, budoji juice, strawberry juice, or processed fruit juices such as nectar juice; tomato juice, cane juice drinks including various vegetable juices; sugars such as sugar or fructose, Synthetic drinks and vitamin-enriched drinks containing synthetic fruit juices using citric acid, coloring agents, flavorings, etc. or adding vitamins as necessary; Lactic acid bacteria drinks; such as mustard oil, sauces, vinegar, mirin, dressings, mayonnaise, Condiments such as ketchup, edible oil, soybean paste, lard, and ketchup; tofu, jam. Favorite items such as butter and marcarin;
In addition, liquid medicines such as Ringer's solution, agricultural chemicals, cosmetics, fragrances, and detergents; furthermore, ketones such as acetone and methyl ethyl ketone; aliphatic hydrocarbons such as n-hexane and n-heptane; alicyclic hydrocarbons such as cyclohexane; benzene. , aromatic hydrocarbons such as toluene and silica; chlorine-containing compounds such as carbon tetrachloride, ethane tetrachloride, and ethylene tetrachloride; or various higher fatty acids; gasoline,
As a container for storing kerosene, petroleum benzene, heavy oil, paint thinner, grease, silicone oil, light oil, machine oil; or liquefied Freon (trade name of DuPont, USA), etc., with little deterioration or weight loss. Useful. Example 1 Ethylene content is 45 mol%, vinyl alcohol content is 55 mol? , the melting point is 158°C by differential thermal analysis (DTA method) when the heating rate is 10°C/71Lm, and the temperature is 3.
The oxygen permeability coefficient (PO2) at 7°C and 0% relative humidity is 0.
23×10″″12cc-CTn/~・SeC-CTL
Hg ethylene-vinyl alcohol copolymer (EVl)
The amount of ethylene is 30 moles? , the vinyl alcohol content is 70 mol%, the melting point according to the DTA method is 183°C, and the oxygen permeability coefficient is 0.07 x 10-12cc@C7! L
/~●Sec●? Two types of ethylene-vinyl γ alcohol copolymers (EV2) of Hg are used as intermediate layers, and the density is 0.9099.
/CCl gamma isotactic polypropylene (PPl) with a melting point of 159°C, a density of 0.909/CCl with a melting point of 154°C and a content of ethylene of 10 moles? ethylene-propylene random conjugate (PP2), the above two types of polypropylene are respectively used as the outermost layer, and the density is 0.9
09/CC, unsaturated carboxylic acid modified polypropylene (AHl) with a melting point of 159°C, density 0.909/CCl
Unsaturated carboxylic acid-modified polypropylene (AH2) with a melting point of 15.4°C, density 0.909/CC Unsaturated carboxylic acid-modified polyethylene-polypropylene mixture (AH3) with melting points of 105°C and 155°C, the above three types The unsaturated carboxylic acid modified product of
Built-in 430mTfL full-flight screw,
An extruder for the outermost layer is equipped with a melt channel that branches into two flow paths, and has a diameter of 40 mm and an effective length of 880 m.
Adhesive layer extruder with a built-in full-flight screw of 500 mm and a melt channel branched into two channels, and an extruder for intermediate layer with a full-flight screw with a diameter of 40 mm and an effective length of 880 mm. Machine combination and multilayer 5
Using a heavy die, a bifluorometer, and a pipe cutter, 24 types of combinations were made, including a parison with an inner diameter of 10 m, a length of 185 mm, a wall thickness of 7.5 mm, and a parison with an open end at both ends, an inner diameter of 15 mm, a length of 100 mm, and a wall thickness of 4.5 mm.
Two types of parisons with open ends were molded and then placed in an atmosphere of 155
After heating for about 30 minutes in a hot air circulation oven precisely set at ℃, the inner diameter is 10 m7IL1 and the length is 185 mm1.
Vertical (pottle height direction) from a pipe with a wall thickness of 7.5 mm
Stretching ratio is 3x, horizontal (bottle circumferential direction) stretching ratio is 3.5
Double, inner diameter 15mm, length 100mm, wall thickness 4.5
For a pipe of mm, the longitudinal stretch magnification is 1.5 and the transverse stretch magnification is 1.5 mm.
Under 5x stretching conditions, wall thickness is 0.6T1tm, internal volume is 30
An attempt was made to mold pottles having a weight of 22 to 249/1 pottle by a so-called final biaxial stretch blowing method.

Efforts were made to mold these bottles so that the composition ratio of the outermost layer: the adhesive layer: the intermediate layer was as close as possible to 100:1:3 in terms of wall thickness. The obtained bottles are summarized in Table 2. Regarding these 24 types of bottles,
Oxygen permeability (QO2) of the bottle according to the method described in No. 0-49379, haze (Hz) according to the measurement method of JIS K67l4, orientation coefficient (T, m, n) according to the aforementioned fluorescence method, 340 for 10 bottles of each type
After filling with the saline solution No. 9 and leaving it in an atmosphere at 1℃ for 3 days and nights, and then taking it out, it was immediately placed in an atmosphere at a temperature of 20℃ for 1.2 m.
Dropping strength when the bottle is dropped from a height of
, ]/10, where F1 means the number of bottles broken in the 1st drop test) and the presence or absence of delamination as determined by the visual judgment of a panel of 5 people. (expressed as the number of bottles N (average value of 5 panelists)), the bottle wall surface is
Cut 50mm in length (mm1), peel at 100m77 in an atmosphere of 20℃ and 60%RH! /Mil7. The peel strength (AT) was determined in the case of .

The results are shown in Table 3. As is clear from Table 3, it can be seen that the multilayer stretch blowing according to the present invention has extremely excellent oxygen gas barrier properties, transparency properties, and delamination resistance.

Comparative Example 1 The ethylene-vinyl alcohol copolymer (EV2) described in Example 1 and the DT with a density of 0.8879/CCl
Using an ethylene-propylene copolymer (PP3) with a melting point of 145°C and an ethylene content of 14 mol% according to method A,
And using the adhesives AHl and AH2 described in Example 1, with the same layer structure and the same extrusion and stretch molding conditions as in Example 1, the wall thickness was 0.6 m7! A biaxially stretched blow bottle having a five-layer structure with an L1 internal volume of 300 CC and a bolt weight of 249/I was obtained.

The obtained pottles are shown in Table 4. For these four types of bottles, the pottle oxygen permeability (QO2') was determined according to the method described in this specification and Example 1. Inner and outer layers (P
P3 layer) orientation coefficient (T, m, n), drop strength (FB
) and the presence or absence of impact delamination (N) due to dropping.

The results are shown in Table 5. As is clear from the results in Table 5, the difference in melting point between the oxygen barrier resin (EV2 in this case) and the oriented thermoplastic resin (PP3 in this comparative example) is 3.
It is known that when the temperature exceeds 5°C, the resulting pottle has poor oxygen permeability (QO2) and drop impact releasability (N).

Comparative Example 2 Ethylene-vinyl alcohol copolymer, EVl and γ isotactic polypropylene, PP described in Example 1
Add PPL to the inner and outer layers without using adhesive using L and E
A two-type, three-layer bottle with Vl as the intermediate layer (inner/outer layer/intermediate layer - 100/3 composition ratio) was molded under the same extrusion and stretch molding conditions as in Example 1, with a wall thickness of 0.6 m and an inner volume of 300 m.
It was obtained by biaxial stretch blow molding so that the weight of one CC bottle was 239/bottle.

According to the method described in Example 1, the oxygen permeability of the bottle (
QO2), orientation coefficient of inner and outer layers (PPl layer) (t・M,
(n), drop strength (FB), and presence or absence of delamination (N) upon impact of a drop (N).

The results are shown in Table 6. As is clear from the results in Table 6, the three-layered bottles that do not use adhesive have both oxygen permeability (QO2) and drop impact releasability (
N) is known to be inferior to a bottle with a five-layer structure provided with an adhesive layer.

The reason why the oxygen permeability is significantly lower than that of the bottle of Example 1 is because a large number of pinholes are generated in the ethylene-vinyl alcohol layer. Comparative Example 3 Ethylene-vinyl alcohol copolymer (EVl), polypropylene (PPl) and adhesive (
Using the same parison molding apparatus and molding conditions as in Example 1, two types of parisons with both ends open as described in Example 1 having the same layer structure and layer composition ratio were molded. did.

These two types of balisongs were heated for about 45 minutes in a hot air circulation oven with an atmosphere precisely set at 122°C, and then the biaxial stretching blowing device used in Example 1 was used.
Biaxial stretching molding was attempted under the same conditions as in Example 1, but
None of the parisons could be stretched, and forming into pottles was unsuccessful.

Comparative example 4 Ethylene content is 19 moles Steam vinyl alcohol content is 81 moles? , the melting point according to the DTA method is 20
1°C, the oxygen permeability coefficient is 0.059 x 10-12cc
-01TL/~・Se? Hg's ethylene-vinyl alcohol copolymer (EV3) and ethylene content is 66 moles? , the vinyl alcohol content is 34 mol%, and the DTA
The melting point according to the method is 123°C, and the oxygen permeability coefficient is 6.4×
10-12CC-CIrL/Cf! T.? For example 1, using polypropylene PPl and PP2 and adhesives AHl and AH2 as described in example 1, using CmHg ethylene-vinyl copolymer (EV4) as the material for the intermediate layer. With the same layer structure and the same extrusion and stretch molding conditions (155℃), the wall thickness was 0.6m7!11
A biaxially stretched blow bottle having an internal volume of 300 cc and a weight of 249/bottle having a five-layer structure was obtained.

The resulting bottles are shown in Table 7. For these pottles, the oxygen permeability (QO2) and inner and outer layers (PP3 layers) of the bottles were determined according to the method described in this specification and Example 1.
The orientation coefficient (T, m, n), drop strength (FB), and presence or absence of impact delamination (N) due to dropping were investigated.

The results are shown in Table 8. As is clear from Table 8, the bottle of this comparative example is inferior in oxygen'\reactance and delamination resistance.

Comparative Example 5 Ethylene-vinyl alcohol copolymers EVl and EV2, polypropylene PPl and PP described in Example 1
2 and using adhesives AHl, AH2 and AH3, 3
A known melt blow molding method involves immediately blowing a multilayer parison extruded from a 5-layer die in a molten state (approximately 220°C).Thus, the same shape, weight, and
A bottle with a layer structure and a layer structure ratio was molded.

For these bottles, the pottle oxygen permeability (QO2) was determined according to the method described in this specification and in Example 1.
, orientation coefficient (T, m, n) of the inner and outer layers (PP3 layers), drop strength (FB), and presence or absence of impact delamination due to dropping (
N) was investigated.

The results are shown in Table 9. Comparing Table 9 with Example 1, it can be seen that the melt blow molded multilayer pottle of this comparative example is at an extremely low level in terms of transparency and drop impact strength.

Furthermore, although the interlayer adhesion strength itself is at a higher level in the melt blow molded bottle of this comparative example than in Example 1, it can be seen that the interlayer peeling resistance in the drop test is inferior to that of the stretched blow molded bottle of Example 1. . Example 2 The two types of ethylene-vinyl alcohol copolymer, EVl, and EV2 described in Example 1 were used as intermediate layers, and the density was 0.99/the melting point by CCsDTA method was 156°C J
Melt index based on ISK6758 is 1.6
dg/nl! Is the ethylene content of t 10 moles? The outermost layer is made of ethylene-propylene copolymer with a density of 0.909/
CC, a full-flight type screw unit with a diameter of 65 mm and an effective length of 1430 m 1 L, using an unsaturated carboxylic acid-modified ethylene-propylene copolymer with a melting point of 154° C. and a melt index of 2.0 dg/Mm as an adhesive layer. An extruder for the outermost layer with a built-in extruder, a full-flight screw with a diameter of 40 mm and an effective length of 880 m7IL, and an extruder for the mounting layer with a built-in full-flight screw with a diameter of 40 mm and an effective length of 880 mu. An extruder for the intermediate layer with a built-in multi-channel adapter, a T-die with a lip width of 0.6 mm and a lip length of 500 m1L,
Using a sheet forming machine, the thickness is 0.8mm and the width is 450mm.
A symmetrical five-layer sheet was molded.

The layer composition ratio of the molded sheet is the thickness ratio of each layer, and the extrusion rate of the three extruders is adjusted so that the ratio of outermost layer: adhesive layer: middle layer = 100:1:3 is adjusted as much as possible. I went. Next, the two types of sheets are heated for about 15 minutes in a hot air circulation oven precisely set to an atmosphere of 155°C, and then, for example, by the plug assist vacuum forming method described in Japanese Patent Application No. 51-57192. Diameter 85m1L1 Height 507! A cylindrical cup with an internal volume of L7lLl of 300 CC and a basis weight of 9 to 109/l was molded. The oxygen permeability (QO2) of these two types of cups was measured using a measurement method similar to the above-mentioned method for measuring oxygen permeability of bottles, based on JISK.
Haze (Hz) according to the measurement method of 67l4, orientation coefficient (T, m, n) by the aforementioned fluorescence method, 1 for each type
0 cups were filled with 3409 saline solution, left in an atmosphere of -1℃ for 3 days and nights, and then taken out.
cprn. 3 under the conditions of amplitude 20mm 1 acceleration 1.8G
The number N of broken cups after a 0-minute free vibration test, the average number of bottles with delamination (ADN) as determined visually by a panel of five people, and the variation in the wall thickness of the middle layer of the molded cup in the vertical direction of the cup. The standard deviations σL and σH were determined in two directions, ie, the circumferential direction of the cup, and the results are shown in Table 10 together with the results of Comparative Examples 6 and 7, which will be described later.

From Table 10, the solid-phase pressure molded cup has excellent oxygen permeability and transparency, and the cup whose intermediate layer is selected to meet the various requirements of the present invention has good delamination resistance and a uniform thickness of the intermediate layer. It turns out that they are extremely good at sex.

Claims (1)

[Scope of Claims] 1. A container having a multilayer structure made of a plurality of types of thermoplastic resins, wherein at least one of the containers has an oxygen permeability coefficient of 5.5×10^-^1^2 cc·cm/cm^2・s
The above-mentioned oxygen barrier property comprising an ethylene-vinyl alcohol copolymer layer having a vinyl alcohol content of 40 to 80 mol% and having an oxygen permeability coefficient of ec・5 cmHg (37°C) or less and sandwiching this layer to constitute the inner layer and the outer layer. and an oriented thermoplastic resin other than the resin, and both resin layers are bonded via an unsaturated carboxylic acid-modified thermoplastic resin layer, and both resins have the formula |T_B-T_A|≦35°C, where T_
B is the melting point or softening point of the oxygen buyer thermoplastic resin (
℃), and T_A represents the melting point or softening point (℃) of the oriented thermoplastic resin.
At least one layer made of oriented thermoplastic resin has a two-dimensional orientation coefficient (l·m) at the thinnest part of the container.
A container with excellent oxygen barrier properties and impact peel resistance, characterized in that the molecules are oriented such that at least one of them has a molecular orientation of 0.05 or more. 2. The oriented thermoplastic resin A is polypropylene or a crystalline ethylene-propylene copolymer with an ethylene content of 1 to 20 mol%, and the layer containing the oriented thermoplastic resin is used as both surface layers of the container. An oxygen barrier thermoplastic resin B made of an ethylene-vinyl alcohol copolymer is present as an intermediate layer of the container, and an unsaturated carboxylic acid-modified thermoplastic resin is present between the inner and outer surface areas of the container and the intermediate layer. Claim 1: There is an adhesive layer made of polymer C, and each of these resin layers is present in a thickness ratio of A:B = 1:1 to 500:1 and B:C = 1:1 to 500:1. Containers listed in section. 3. The container according to claim 1, wherein the oxygen barrier resin is molecularly oriented. 4. The container according to claim 1 or 2, wherein the container is a stretched multilayer bottle. 5. The container according to claim 1 or 2, wherein the container is a stretched multilayer cup. 6 Oxygen permeability coefficient is 5.5×10^-^1^2cc・c
At least one component consisting of an ethylene-vinyl alcohol copolymer having a vinyl alcohol content of 40 to 80 mol% and having a content of 40 to 80 mol% of m/cm^2・^s^e^ccmHg (37°C) or less
and an oriented thermoplastic resin layer other than the above-mentioned oxygen barrier resin sandwiching this layer to constitute an inner layer and an outer layer, and both of these resin layers are unsaturated carboxylic acid-modified thermoplastic resin layers. A parison or sheet with a multilayer structure bonded via the above is molded by simultaneous melt extrusion; where both resins are expressed by the following formula |T_B-T_A|≦35°C, where T_B is the oxygen barrier thermoplastic resin. represents the melting point or softening point (°C) of the oriented thermoplastic resin, and T_A represents the melting point or softening point (°C) of the oriented thermoplastic resin; T_B | ≦30°C where T_B has the above-mentioned meaning, T_m represents the molding temperature (°C), and the oriented thermoplastic resin at least at the thinnest part of the container Excellent oxygen barrier properties and impact peeling resistance, characterized by being molded into the shape of a container under conditions that cause molecular orientation of at least one of the two-dimensional orientation coefficients (l, m) of 0.05 or more. Method of manufacturing containers. 7. The method according to claim 6, wherein the multilayer parison is stretch-blow-molded in biaxial directions sequentially or simultaneously at the molding temperature (T_m). 8. The method according to claim 6, wherein the multilayer sheet is drawn into a cup at the forming temperature (T_m).