JPH01153444A - Hollow container - Google Patents

Abstract

PURPOSE:To provide an excellent barrier characteristic, mechanical strength and creep resistance, by forming the inner and outer layers of polyester consisting mainly of ethylene terephthalate and molding a parison by biaxial stretching blow method with the specified blended components as an intermediate layer. CONSTITUTION:The container molded by biaxial stretching blow method using a plastic parison of multiple layers comprises the inner and outer layers formed of polyester consisting mainly of ethylene terephthalate which has the sum of the initial elastic modulus and retarded elastic modulus of not more than 1X10<10>dyne/cm<2> at a temperature of 23 deg.C and under a stress of 7X10<7>dyne/cm<2> and the stationary flow viscosity coefficient of not less than 1X10<17>poise and the intermediate layer consisting of a plurality of types of resins which have a solubility index of not less than 9.5 and one type of which consists of blended components whose oxygen transmission coefficient is not more than 5X10<-11>cc.cm/cm<2>.sec.cmHg and contains the polyester of the same surface condition as above-mentioned and the polyamides whose 20 to 80 molar percentage of the sum of diamine, dicarbonic acid and amino carbonic acid consists of the components containing aromatic groups, in the weight proportions within the range from 5:95 to 85:15.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to stretch blow molded structures such as plastic bottles, and more specifically, to excellent gas barrier properties against carbon dioxide, carbon dioxide, etc., and mechanical properties. Stretch blow molded structures having a desirable combination of strength, hardness, creep resistance and transparency.

(Prior art and its problems) Conventionally, thermoplastic resins such as polyolefins, particularly polypropylene, are molded into a parison with or without a bottom, and this parison is then compared, for example, with respect to the melting temperature of the resin. The step of stretching the parison in its axial direction at a relatively low temperature and the step of expanding the parison in a direction perpendicular to the axis are performed simultaneously or in this order (i.e. sequentially), thereby forming a biaxially stretched blow-molded structure. known to be manufactured. This biaxially stretched blow molded product has superior mechanical strength, hardness, creep resistance, and transparency compared to ordinary blow molded products as a result of the biaxially stretched orientation. The use of pressure-resistant or gas-barrier bottles for filling and storing liquid foods such as carbonated drinks, medicines, liquid cosmetics, aerosol contents, etc. is still not satisfactory.

That is, even though resins such as the above-mentioned polyolefins have excellent biaxial stretchability, and are particularly excellent in transparency and mechanical strength, the disadvantage is that they have relatively high permeability to gases such as oxygen or carbon dioxide. On the other hand, it is nearly impossible to apply this biaxial stretch blowing technique to thermoplastic resins that have excellent gas barrier properties (gas permeability resistance) against oxygen or carbon dioxide gas, in terms of stretchability.

In order to overcome this drawback, the present inventors proposed in Japanese Patent Publication No. 57-42493 that a thermoplastic resin with excellent gas barrier properties, which is impossible or difficult to biaxially stretch blow molded by itself, is A blow-molded structure is disclosed that is blended with a melt-extrudable thermoplastic resin that satisfies conditions and has a layer of this blend.

After discovering the above-mentioned invention of imparting biaxial stretch blow moldability to a thermoplastic resin with excellent gas barrier properties for which biaxial stretch blow molding is impossible or difficult, the present inventors continued further intensive research. As a result, they discovered a blow molded structure with high gas resistance and improved mechanical strength using a thermoplastic resin suitable for biaxial stretch blow molding.

That is, the object of the present invention is to provide excellent gas/heliquity against oxygen, carbon dioxide, etc., transparency, and strength.

It is an object of the present invention to provide a biaxially stretched blow-molded structure having an excellent combination of physical properties such as creep resistance and hardness.

(Means for Solving the Problems) According to the present invention, a multilayer plastic parison is formed by biaxial stretch blow molding, and the inner and outer surface layers are heated at a temperature of 23°C and a stress of 7 X I O' dyne/cm2. Below, the sum of the initial elastic modulus and delayed elastic modulus is lXl0IOdyn
e/cm2 or less, and the steady flow viscosity is IXIQ+1p
oise or more and the delay time is 6 x 106 s
The intermediate layer is made of a plurality of resins having a solubility index of 9.5 or more, and the oxygen permeability coefficient of at least one of the resins is 5'X 10-'lcc/c.
m/cm'-sec-cmHg or less, the difference in solubility index between each resin is 4.5 or less, and the hollow container is made of a blend having a higher elongation rate than the arithmetic mean elongation rate of the resin components, The blend consists of a polyester mainly containing medium ethylene terephthalate, an amine component,
20 to 80 mol% of the total dicarboxylic acid component and aminocarboxylic acid component consists of a blend containing polyamide, etc. consisting of an aromatic group-containing component in a weight ratio of 5 = 95 to 85:15, There is provided a hollow container characterized in that the inner and outer surface layers are made of polyester containing a medium amount of ethylene terephthalate.

(Function) The blend that becomes the intermediate layer of the blow-molded structure of the present invention is composed of multiple types of resins having a solubility index of 9.5 or more, and at least one of the resins has an oxygen permeability coefficient of 5XIO-Rocc-
cm/ca+z-sec-cmHg or less (37℃ and O
%RH), and it is important to select and combine resins so that the difference in solubility index between each resin is 4.5 or less in relation to two-wheel stretch formability and gas permeation resistance. .

As used herein, solubility index
For example, J, BR
ANDRUP et al. “Polymer Handbook”
``4th tun (John Wiley & 5oons).

Inc., Publishing, 1967), it is defined as the power of the cohesive energy density (cal/cc). This solubility index is related to the strength of hydrogen bonds in thermoplastic resins, and is related to the strength of hydrogen bonds in thermoplastic resins.
Thermoplastic resin polymers containing (1-1) in the main chain or side chain generally exhibit a relatively large solubility index of 9.5 or more, depending on the content 1-1 and distribution state of these polar groups. .

For representative thermoplastic resins, this S
The p values are shown in Table 1 below. According to Table 1, it can be seen that polymers containing polar groups such as polyvinyl alcohol and polyacrylonitrile have large solubility indices. However, these polyvinyl alcohol and polyacrylonitrile cannot be melt-extruded, and therefore, they must be modified into a melt-extrudable copolymer form before use for the purpose of the present invention.

Table 1: SP value of thermoplastic resin Oxygen permeability coefficient is a unique value that expresses the ease of oxygen permeation peculiar to that resin. ) (7) 940
X 10-If [cc-cm/cm2/sec-c
For those smaller than mHgl, Epal (F!+ (ethylene-vinyl acetate copolymer) 0.033 x 1 x
1010 [cc-cm/cm//sec・cmHgl
(Both values are at 37° C. and 0% RH). For the value of the oxygen permeability coefficient of each resin, please refer to Japanese Patent Publication No. 57-42493.

In the present invention, the polyester mainly composed of ethylene terephthalate units used for the inner and outer surface layers and the blend layer has excellent mechanical properties such as moldability and creep resistance, as represented by polyethylene terephthalate, and also has excellent mechanical properties such as moldability and creep resistance. Since molecular orientation is possible in this direction, it is suitable for biaxial stretch blow molding, and has relatively good gas barrier properties.

Since the polyamide used in the blend layer of the present invention contains a diamine component, a dicarboxylic acid component, and an aminocarboxylic acid component, it exhibits a solubility index of 9.5 or more, which is necessary for the present invention. The solubility index is closely related to the strength of hydrogen bonding in thermoplastic resins. Plastic polymers generally exhibit a relatively large solubility index of 9.5 or more, depending on the content and distribution of these polar groups.

Furthermore, this polyamide contains 20 to 8 of the total amount of diamine component, dicarboxylic acid component, and aminocarboxylic acid component.
Since 0 mol% of the component is an aromatic group-containing component, a strong interlayer bond is formed between the polyester and the polyester mainly composed of ethylene terephthalate units, and gas barrier properties are improved. If the aromatic component is less than the above range, the gas barrier property will be unsatisfactory, and if the aromatic component is more than the above range, although the gas barrier property may be satisfied, the moldability will be unsatisfactory. This makes extrusion, etc. difficult. This is thought to be due to the fact that the aromatic group segment is included in the main chain, which improves the chemical affinity with the polyester mainly composed of ethylene terephthalate units.

In the present invention, the weight ratio of the polyester mainly containing ethylene terephthalate units to the polyamide is 5:95 to 85:15, particularly 10.90 to 80:2.
It is important that the amount of polyamide be contained in a weight ratio of 0. If the amount of polyamide is less than the above range, the gas barrier properties will be unsatisfactory, and if the amount of polyamide is greater than the above range, the moldability will be poor. It becomes unsatisfactory.

In the present invention, it is important to form a blend of multiple types of thermoplastic resins in such a quantitative ratio that a blend having a higher elongation rate (G) than their arithmetic average elongation rate (G) is formed. It is. In this specification, the elongation rate (ε) is defined by the following formula, where L+ represents the fracture length in the parison direction or the direction perpendicular to the parison, in which the fracture occurs first, and LO represents the direction corresponding to the fracture. represents the initial length of

It is a value expressed as , and the arithmetic average growth rate (τ) =
ε1・Xl +ε,...X2+...+(,・X,
.

= Σ ε, 1・x,
(2) n=1 In the formula, ε5 is the elongation rate of a sheet formed by extruding a thermoplastic resin mainly composed of ethylene terephthalate units contained in the blend, and The weight of the thermoplastic resin is 111 parts, and n is 2 or more and is equal to the number of thermoplastic resins contained in the blend.

This is the value defined by . In the present invention, the arithmetic mean elongation rate (τ
) to form a blend.

In the present invention, when a plurality of types of thermoplastic resins are combined so as to satisfy the various requirements described above, an unexpected change in stretch blow moldability occurs. The reason why biaxial stretch blow moldability is significantly improved in the present invention is not yet fully clear. However, as shown by the high solubility index, the thermoplastic resins used in the present invention have polar groups that form strong hydrogen bonds between polymer chains, and these resins also have polar groups that form strong hydrogen bonds between polymer chains. One reason is that in the blend of the present invention, multiple types of thermoplastic resins mutually act to plasticize the resins. It can be considered as one.

In the present invention, it is also important to adopt a sandwich structure in which the blend is sandwiched between polyesters mainly containing ethylene terephthalate. This structure allows
The properties of polyester mainly composed of ethylene terephthalate units, which are suitable for biaxial stretch blow molding, can be applied to the blend layer containing polyamide resin, which is not originally suitable for biaxial stretch blow molding, and can be applied to the blend layer while maintaining high gas barrier properties. This makes axial stretch blow molding possible.

(Preferred embodiment of the invention) Polyester mainly composed of ethylene terephthalate units As the polyester mainly composed of ethylene terephthalate units used in the present invention, polyethylene terephthalate is preferably used. Copolyesters based on terephthalate units and containing other polyester units may also be used. Copolymerization components for forming such a copolyester include isophthalic acid, p-β-oxyethoxybenzoic acid, naphthalene-2,6-dicarboxylic acid, diphenoxyethane-4,4°-dicarboxylic acid, and 5-sodium sulfoisophthalate. Acid, dicarboxylic acid components such as adipic acid, sebacic acid or their alkyl ester derivatives, brolerin glycol, 1,4-butanediol-neopentyl glycol, 1,6-hexylene glycol, cyclohexane dimetatool, bisphenol A. Glycol components such as ethylene oxide adducts, diethylene glycol, and triethylene glycol can be mentioned.

From the viewpoint of the mechanical properties of the vessel wall, the thermoplastic polyester used should have an intrinsic viscosity of 0.5 or more, especially 0.6 at 30°C in a mixed solvent of phenol/tetrachloroethane in a weight ratio of 50:50. The above is desirable. Furthermore, this polyester can also contain additives such as coloring agents such as pigments and dyes, ultraviolet absorbers, and antistatic agents.

Polyamide component The polyamide component used in the present invention itself has excellent gas barrier properties and moldability, and by blending it with the above-mentioned polyester, it can be used without impairing the moldability of the polyester. ,
Gas barrier properties are significantly improved, and mechanical properties such as impact resistance can also be improved.

Preferably, the polyamide component is a copolymer having, but not limited to, amide repeating units represented by the following formula.

-CO-R-NH- (3) -Co-R+ -CONH-R2-NH- (4) In the formula,
R, R, and R2 are any one of an aminocarboxylic acid component, a diamine component, and a dicarboxylic acid component. However, R1R1 and R2 are each different groups.

It is important that 20 to 80 mol% of the total ψ of the diamine component, dicarboxylic acid component, and aminocarboxylic acid component contained in the polyamide component is an aromatic group-containing component. The diamine component, dicarboxylic acid component and aminocarboxylic acid component having groups are:
In combination with diamines, dicarboxylic acids, and aminocarboxylic acids that do not have aromatic groups, they constitute amide repeating units.

Examples of the diamine component, dicarboxylic acid component, and aminocarboxylic acid component constituting the amide repeating unit of the polyamide used in the present invention are as follows.

Cyamine component (V aromatic diamine component metaxylylene diamine, para-xylylene diamine, para-bis(2-aminoethyl)benzene, benzidine,
4.4'-diaminostilbenzene, 4.4'-diaminostilbenzene-2,2'-disulfonic acid, 4.4'
-diaminophenyl sulfoxide, 4,4°-diaminodiphenylsulfone, 2,4-diaminoazobenzene,
1,5-diaminonaphthalene, 3,6-diamitacridine.

(ri) Diamine component having no aromatic group: an aliphatic or alicyclic diamine having carbon fi of 2 to 20 carbon atoms. For example, alkyl-substituted diamines such as ethylenediamine, trimethylenediamine, tetramethylenediamine, propylenediamine, hexamethylenediamine, and 2.2.4-trimethylhexamethylenediamine, and piperazine.

Dicarboxylic acid component ■ Aromatic dicarboxylic acid component Terephthalic acid, phthalic acid, isophthalic acid, naphthalene dicarboxylic acid, diphenyl dicarboxylic acid, naphthalene dicarboxylic acid, diphenoxyethane dicarboxylic acid, etc.

(2) Dicarboxylic acid component having no aromatic group A resinous, alicyclic or aromatic dicarboxylic acid component unit having a carbon atom number in the range of 5 to 18, specifically glutamic acid, α,ω-aliphatic dicarboxylic acids such as adipic acid, pimelic acid, superric acid, azelaic acid, and sebacic acid; alicyclic dicarboxylic acids such as cyclohexane-1,3-dicarboxylic acid and cyclohexane-1,4-dicarboxylic acid; etc.

Aminocarboxylic acid component The aminocarboxylic acid component has 5 to 1 carbon atoms.
2. It is preferably 6 to 10 aminocarboxylic acid component units, and includes not only aminocarboxylic acids but also lactams that form aminocarboxylic acid component units in the co-condensed polyamide molecule.

Specifically, the aminocarboxylic acid component units include 7-amine hebutanoic acid, para-aminomethylbenzoic acid, δ
Examples include -aminovaleric acid, ε-aminocaproic acid, ω-ami7caprylic acid, ω-amine capric acid, and ε-caprolactam.

Specific examples of the polyamide having the above-mentioned amide repeating unit include those disclosed in Japanese Patent Publication No. 1156/1983, Japanese Patent Publication No. 5751/1983, Japanese Patent Publication No. 5753/1983, Japanese Patent Publication No. 10196/1983, Japanese Patent Publication No. 50-10196, Kaisho 50-29697
No., JP-A-60-232952, JP-A-60-240
It is possible to use polyamides disclosed in No. 452 and other publications.

Generally, the molecular weight of polyamide can be used without any particular restriction as long as it is within a range that has film forming ability, but 98%
Dissolve 1 g of polymer in 10.0 cc of sulfuric acid and heat at 20°C.
It is generally desirable that the relative viscosity is in the range of 1.8 to 3.5 when measured at .

When polyamides with a relative viscosity of less than 1.8 are combined with other resins and subjected to two-wheel stretch blow molding, it is difficult to provide a molded product with excellent mechanical strength. It appears that polyamides with a higher than the above range generally have poor melt moldability.

In one embodiment of the invention, the multilayer structure comprises at least one layer of the aforementioned blend and a temperature of 23°C and 7 x 10
-The sum of the initial elastic modulus and the delayed elastic modulus under the stress of 'dyne/am' is greater than or equal to lX1010dmane/crm2, the steady flow viscosity is greater than or equal to I It is molded into a parison as a laminated structure consisting of at least one layer of thermoplastic resin having a thickness of 6 x 106 sec or less, resulting in a multilayer blow-molded product with even better creep resistance.

Generally, a viscoelastic body such as a thermoplastic polymer is subjected to a period of time E.
When stress S is applied, when t is short, the nose behaves like a viscoelastic body; when t increases, the influence of viscosity appears in addition to elasticity, and the system behaves viscoelastically; At sufficiently large locations, viscous flow occurs. These viscoelastic behaviors can be expressed in a model using the initial characteristics of the above-mentioned initial elastic modulus, delayed elastic modulus, steady flow viscosity, and delay time.

When a blow-molded structure is used as a pressure-resistant container such as a carbonated beverage container or an aerosol container, the material constituting the container wall must not only have excellent gas barrier properties but also resist the pressure of the contents. Appropriate hardness and a combination of creep resistance and impact resistance are required.

As shown in Figure JS1, it is also important to form a sandwich structure in which the thermoplastic resin a is sandwiched between the blends.According to a preferred embodiment of the present invention, the gas barrier
By laminating a thermoplastic resin layer with viscoelastic properties in the above range on the blend layer having excellent properties,
Compared to blow molded structures consisting of a blend layer,
Creep resistance, hardness, etc. necessary for pressure containers can be significantly improved, and such a multilayer structure can also improve impact resistance.

Among the viscoelastic properties mentioned above, the sum of the initial elastic modulus and delayed elastic modulus is related to the hardness of the container, and in the present invention,
From the standpoint of pressure resistance, the temperature is 23℃ and the stress is 7 x 101.
Under the condition of d7ne/c+e2, the sum is I X 1
×1010dyr+e/c+s2 or more, especially 2X101
It is important that it is 0dyr+e/c+s2 or more.

In addition, the steady flow viscosity and delay time are related to creep resistance. In the present invention, from the viewpoint of preventing creep, the steady flow viscosity is set to be at least I X I OI' Polse, particularly at least 5 X I O' Polse. It is important that the delay time is less than 6 x 106 sec, especially less than 3 x 106 sec.

In the present invention, the blend layer with excellent gas permeability resistance and the thermoplastic resin with excellent creep resistance can be laminated using various joining methods and multilayer configurations, but the blend layer itself may be made of polyamide, etc. When containing a thermoplastic resin having a carbonyl group in the main chain or side chain, this blend itself generally exhibits excellent thermal adhesion to the thermoplastic resin, which has excellent creep resistance, so it is particularly Directly laminated structures can be obtained by co-melt extrusion without using other adhesive means.

Molding method The blow-molded structure of the present invention can be manufactured by any method known per se, except that a parison is formed from a multilayer structure of the above-mentioned blend with a creep-resistant thermoplastic resin. 0 For example, the parison used in biaxial stretch blow molding.

It can be molded by any means such as co-extrusion molding or co-injection molding.

For example, the multilayer structure may be coextruded into a pipe, and the pipe may be cut to length. A mandrel is inserted into the cut pipe, and using a suitable molding die such as a split mold, it is formed into an open-bottomed parison 1 having the shape shown in FIG. 2, for example. That is, in FIG. 2, this parison l consists of a cylindrical body 4 which is open at one end 2 and closed at the other end 3, and has a bead at the open end 2 or the vicinity thereof. A lid fastening mechanism such as 3 or a male screw 5 is integrally formed with the cylindrical body 4. The molding temperature for this parison is generally not limited as long as it is above the softening temperature of the resin, but it is generally best to select a temperature within the temperature range of 180 to 350 degrees Celsius at which the pipe ends are completely welded. . Instead of manufacturing the open-bottomed parison l from a previously coextruded pipe, the open-bottomed parison is co-injection molded using an openable and closable mold with a cavity shaped as shown in No. 21A. It can also be manufactured by

In order to co-extrude the above-mentioned blend and creep-resistant thermoplastic resin as a multilayer structure, a number of extruders 1 corresponding to the types of resin layers to be co-extruded are required, for example, an extruder for the blend and a creep-resistant resin. Using an extruder for extrusion, each of these resin streams is extruded through a multilayer die into a multilayer parison. Also in multilayer injection molding, a number of injection molding machines corresponding to the types of resin layers are used, and a plurality of types of resin streams are injected into a mold cavity through a composite nozzle.

These multi-layer open-bottomed parisons produced by coextrusion or injection co-injection are then stretched in the axial direction of the parison in a split mold, and are then stretched in the axial direction of the parison by blowing fluid in a direction perpendicular to the said direction. Stretch. The stretching in the axial direction and the stretching in the direction perpendicular to the axial direction may be performed simultaneously or sequentially in this order.

For example, an example of the manufacturing method of the blow-molded container of the present invention is shown: In FIG. 6 and 6 move relative to each other in the direction perpendicular to the hair, thereby stretching the parison I in its axial direction. At the same time, fluid is blown into the parison 1 from a fluid inlet 8 provided on the mandrel 9, thereby stretching the parison in a direction perpendicular to the axial direction and forming it into a bottle shape.

At this time, after the relative movement between the mandrel 9 and the split mold 6 is completed, if fluid is blown into the mandrel through a blowing opening provided in the mandrel or another needle, so-called sequential biaxial stretching will be performed. As an alternative to using a preformed open-bottomed parison, a continuous pipe-like parison can be used for two-wheel stretch blow molding, in which case the pipe is given a gold 56 neck finish prior to drawing. The mouth part is shaped by interlocking with the parts.

In addition, depending on the type and combination of resins, for example, the method disclosed in Japanese Patent Publication No. 44-25478, or the method of holding both ends of a bottomless resin tubular body with clamps and first holding the tubular body vertically. It is also possible to use a method in which, after stretching, the tubular body is sandwiched between blow molds, fluid is injected from one end to expand the tubular body, and the bottom of the molded product is welded at the same time as blow molding.

The conditions for the two-wheel stretch blowing of the parison vary depending on the composition of the resin blend used, etc. Since the polyester mainly composed of ethylene terephthalate units of the present invention is a resin with relatively low crystallinity, it will crystallize from above its glass transition temperature. Stretch blow molding is preferably carried out within a temperature range below the starting temperature, and since the crystallization rate is relatively fast, the extruded parison is cooled at a cooling rate of 1 to 5000°C/ir+, preferably 5 to 1200°C/win. If the molded product is rapidly cooled and stretch blow molded under the above-mentioned conditions, the transparency of the molded product will be further improved. In any of these cases, if the resin blend or multilayer parison exhibits thermal behavior specific to each resin, it is necessary to use the resin with a higher crystallization temperature or glass transition point as the standard. It is a matter of course that the stretchability of a parison made of a multilayer structure of the blend of the present invention and a creep-resistant resin can be determined by measuring the load-elongation curve of this parison at each temperature. . That is, the lower limit of the temperature at which stretch blow molding can be performed can be easily determined as the temperature at which so-called necking does not occur in the sample cut from the parison.

The stretching effect in the axial direction of the parison and in the direction perpendicular to this is
Although it differs significantly depending on the composition of the blend, in general, the length of a stretched sample left in an atmosphere of 50 to 150°C for 10 to 15 minutes is measured, and the structure after stretch molding is determined as follows: In the formula, L< is the length of the stretch-blow-molded product, and L is the length of the stretch-blow-molded product, and L is the length of the stretch-blow-molded product, and if the heat shrinkage rate (σ) defined by the equilibrium length after the shrinkage treatment is at least 5% or more, especially 7% or more, the material can be cut. Effects such as improved creep properties, hardness, and transparency are provided by stretching orientation.

For this reason, generally speaking, it is desirable that the parison's stretching ratio in the axial direction be in the range of 1.1 to 5.0 times, particularly 1.2 to 3.5 times; The stretching ratio in the direction is desirably in the range of 1.5 to z5 times, particularly 2.0 to 6.5 times.

The stretching speed of the parison varies depending on the type of resin, and may be within a speed range such that the above-mentioned stretching effect is produced in the stretched molded product, but in particular, the stretching speed is 10 to 6,000,000%.
/+in is preferable.

As the fluid blown into the parison through the mandrel or needle, air, nitrogen, carbon dioxide vapor, or a mixture thereof can be used, and the pressure is generally preferably in the range of 3 to 30 Kg/Cff12 (gauge). .

The obtained stretch-molded structure can be heat-treated under high-speed conditions in a stretch-blow-molding mold or in a mold separate from this mold to heat-set the orientation. Heat treatment is generally 1
At a temperature of 00 to 200 °C, especially 110 to 170 °C,
It is best to do this for 1 second to 1 minute.

Blow molded structure The blow molded structure of the present invention generally has a molecular weight of 0.01 to 5 dl/g, particularly 0.05 dl/g, although it differs depending on its use.
It can be produced with a basis weight (volume per g of resin) of from 2 to 2 dl/g, and the thickness of the container wall can be in the range of 0.02 to 3 mm, particularly 0.05 to 1.5 ff1m, Within this range, the desired combination of gas barrier properties, mechanical strength, creep resistance, hardness and transparency can be achieved.

The blow-molded structure of the present invention is further comprised of the above-described blend and is biaxially stretched.
When the layers of the blend have the same thickness, compared to the undrawn material, the m element permeability is less than 100%, especially less than 100%, the carbon dioxide gas permeability is less than η, especially less than 200%, and the water vapor permeability is less than 100%, especially less than 200%. For example, for low-malt beer such as beer and carbonated soft drinks that have a permeability, even trace amounts of oxygen that penetrate through the plastic container wall have a significant effect on the flavor. According to this method, the barrier properties against oxygen can be maintained within the above range, and as a result, the shelf life of these beverages can be significantly improved. Furthermore, the blow-molded structure of the present invention can maintain the drop in carbon dioxide pressure at a significantly lower level than in conventional plastic bottles.

Thus, the blow-molded structure of the present invention can store contents such as liquid or paste foods and beverages, liquid medicines, agricultural chemicals, cosmetics, cosmetics, detergents, etc. with little deterioration or weight loss. .

(Effects of the Invention) According to the present invention, the inner and outer layers are made of a polyester mainly composed of ethylene terephthalate units that satisfies the above-mentioned requirements, and the polyester mainly composed of ethylene terephthalate units, a diamine component, a dicarboxylic acid component and an amino Polyamide etc. in which 20 to 80 mol% of the total amount of carboxylic acid components is an aromatic group-containing component is 5:95.
By using the combination with a blend layer containing a weight ratio of 85:15 for parison molding, it is possible to maintain high gas barrier properties while maintaining high gas barrier properties, which was impossible or difficult to do with either resin alone. It has become possible to perform axial stretch blow molding, and it has also become possible to significantly improve the stretching ratio during molding, and the hollow container obtained by the present invention has excellent barrier properties, mechanical strength, hardness, and creep resistance. and transparency.

(Example) The present invention will be explained in more detail in the following examples.

In addition, each measurement in each Example was performed according to the following method.

(1) Oxygen permeability of bottle: Measurement was performed according to the method described in Japanese Patent Publication No. 57-48459. The storage conditions for each sample were at a temperature of 37°C.
Humidity outside one container is 20% RH Humidity inside one container is lOO% RH
Met. Measurements were carried out five times for each type of bottle, and the arithmetic average value was used as the result.

(2) Moisture reduction rate: Fill 3 wooden bottles for each type with approximately 1000g of tap water, heat seal the mouth with a film with aluminum foil and cap, and then place in an atmosphere of 50℃ and 1O%RH. After being left for 7 days, the moisture reduction rate (L, ) is expressed by the following formula: L, = l 00X (Lo - Lr) /Lo
(%) In the formula, LO represents the initial water weight, and L7 represents the water weight after being left in the above atmosphere for 7 days.

I asked for The result is the arithmetic mean of three trees.

(3) Drop strength: Ten bottles of each type were filled with 1,200 g of 15% saline solution and dropped in an atmosphere of -1°C for 30 minutes.
After leaving it for day and night and taking it out, immediately heat it at a temperature of 20℃ for 1 hour.
．． The bottle was dropped from a height of 2 m onto a concrete surface so that the bottom of the bottle touched it. And the fall strength (FB) defined by the following formula.

Fe=100X(10-Fl)/10(%) In the formula, Fl
means the number of bottles broken in the first drop.

I asked for

(4) Carbon dioxide loss: The measurement of carbon dioxide gas loss followed the following procedure.

The results show the average value of N=5 trees: ■Preliminary, 21
．． Prepare 8 g of citric acid and 26.2 g of sodium bicarbonate in equal quantities to the number of samples to be measured.

5) Add 50-80% of the droplet volume into the empty sample bottle.
% of tap water.

(Hisashi) Immediately after adding the aforementioned citric acid and sodium bicarbonate into the sample bottle, and then filling the bottle with tap water, the M40 bottle manufactured by Toyo Food Machinery Co., Ltd.
Seal the mouth of the bottle with an aluminum cap with a septum using a 1A-PN sealing machine.

→) Each sample bottle obtained in this way was
Store overnight in a high temperature, high humidity tank at 60% RH.

■After that, insert a pressure gauge with a three-way cock from the septum of the cap, open the drain valve, and find that the equilibrium pressure (gauge thickness) inside the bottle is 3.95 Kg/cta' (4.0 gas volume, hereinafter referred to as GV,...!) Remove the gas until it becomes .).

[Co., Ltd.] The sample bottle in which the internal pressure of the bottle was adjusted was re-injected at 22
Place in a high temperature, high humidity bath at 160% RH and stabilize for 6 hours.

(2) After a predetermined period of time, the sample bottle is taken out of the high-temperature and high-humidity bath, immersed in water in an ultrasonic washer at a water temperature of 20 to 22°C, and subjected to ultrasonic waves for 5 minutes to lightly vibrate the bottle.

(e) Immediately insert a pressure gauge through the septum,
Pressure (gauge pressure) 1.0 minutes after insertion.

(■ Based on the measured gauge pressure and temperature, the following formula at 22°C is plotted from the gas volume conversion table. are shown respectively.

Calculate the gas volume using

In addition, in each table in each example, carbon dioxide loss, ΔC
02 (%) is the following formula.

ΔCO2 = 100
y6 represents the initial gas volume, that is, the GV after completing the operation (2) above.

(5) Elongation rate: The wall surface of each type of bottle is measured in the parison direction (bottle axis direction).
Each piece was cut to a length of 100 mm and a width of 10 aoe and left at room temperature overnight. After that, the initial length (Lo) of the above sample was measured using an Instron type tensile tester.
is 50 * 0.5ff1ffl, pulling speed is 10
Measurement was performed at room temperature under the condition of 0 mma min, and the elongation at break (elongation rate, ε) was calculated from the obtained breaking length (Lt) according to formula (1) in the specification. Results are expressed as an arithmetic mean of 10 values for each sample.

Example 1 An extruder for inner and outer layers equipped with a built-in full-flight screw with a diameter of 65 mm and an effective length of 1430 mm, and a melt channel branched into two flow paths, and an extruder with a diameter of 50 m.
m, in combination with a middle layer extruder equipped with a full-flight screw with an effective length of 1100 mm, and a multi-layer triple die to produce a pipe with an inner diameter of 2411111 mm, a length of 11 mm) and a wall thickness of 3.4 + wm. Extruded. Then, according to the method described in this specification, one end of the pipe is fused under conditions of 300°C to form a bottom part, and then
A mouth portion was formed on the opposite end by compression molding (300° C.) to form a parison (preform) with an opening and a bottom as shown in FIG.

The synthetic resin used for molding has an inner and outer layer with an intrinsic viscosity of 0.
9. Differential thermal analysis method (heating rate 10°C/ff1in)
The melting point is 255°C, the solubility index is 10.7, and 23
The sum of the initial elastic modulus and delayed elastic modulus is 22.4 Xl at a temperature of ℃ and a stress of 7
010d7ne/cm2, steady flow viscosity is 35. lX1
011poise, delay time 0.26X106se
c polyethylene adipamide (MXD 6, relative viscosity 2.22, melting point according to the differential thermal analysis method 243 ° C., solubility number 12.2, oxygen permeability coefficient 0. I x 10-
It was a blend of 50:50 (by weight) of PET and the above-mentioned PET.

Using a prototype biaxial stretch blow molding machine, the obtained open-bottomed barizun was heated for 45 seconds at a temperature of 110°C, and then blow molded at 30Kz/cts2 in a mold at a temperature of 10°C. Two-wheel stretch blowing was performed under pressure for 8 seconds to form a cylindrical multilayer bottle with a dripping internal volume of 1150 ml and a basis weight of 0.25 dl/g. The layer composition ratio of the bottle was 3=2:1 in thickness ratio of outer layer: middle layer: inner layer. Hereinafter, this multilayer bottle will be referred to as A.

For comparison, using only the extruder for the inner and outer layers, the PET alone, the MXD6 alone, and the PET were MXD
Each bottle (the shape, the internal volume of the droplet, and the basis weight are the same as above) consisting of a blend with a mixing ratio (weight ratio) of 50:50 and 6 was molded under the above-mentioned extrusion, biaxial stretching and blowing conditions. Hereinafter, the PET single bottle will be referred to as B, the MXD6 single bottle as C1, and the blend bottle as D, respectively.

Furthermore, for comparison, a multilayer parison (constituent ratio: outer layer: intermediate layer: inner layer = 3:2:1) was coextruded using the multilayer extruder system described above, and the molten parison was Using a direct/blow mold, the internal volume of the droplet is 115
A cylindrical direct blow multilayer bottle with a weight of 0.0 ml and a basis weight of 0.25 dl/g was molded. Hereinafter, this multilayer bottle will be referred to as E.

Regarding the five types of bottles A to E obtained.

According to each method described above, (1) oxidation permeability, (2) moisture loss rate, (3) drop strength, (4) carbon dioxide loss, and (
5) The elongation rate was measured. The results are shown in Table 2.

Example 2 Using the coextrusion system and biaxial stretching blowing device described in Example 1, polyethylene terephthalate (CPET) used in Example 1 was used for the inner and outer layers, and methane in isophthalic acid and adipic acid was used for the intermediate layer. Xylylene diamine cocondensation polyamide (IMX6, composition (mole) ratio is 21:29:50
, relative viscosity is 1.95, glass transition temperature is 103°C1
The solubility index is 11.9. Oxygen permeability coefficient is 0.2 x l
011cc・cm/cm2・sec-craHg)
and the above-mentioned PET (ff! quantitative ratio) is 80:20
A multilayer bottle with a three-layer structure containing the blend was molded. The shape, internal volume, basis weight, and wall thickness ratio of the obtained multilayer bottle were all the same as in Example 1.

Regarding the bottle, according to the method described above, (1) oxidation permeability, (2) water loss rate, (3) drop strength, and (4)
f
C), moisture reduction rate is 0.29%, drop strength is 100% (
No damage), carbon dioxide loss was 3.4% and elongation rate was 39
．． It was 2%.

[Brief explanation of the drawing]

FIG. 1 is an enlarged view showing the layer structure of the blow-molded product of the present invention, and FIG. 2 is a sectional view showing an example of a bottomed parison used for manufacturing the blow-molded product of the present invention. , FIG. 3 is an explanatory diagram for explaining the biaxial stretching molding method. a... Thermoplastic resin, b... Blend l... Baricin, 3... Bead, 4... Cylindrical body, 6... Split mold, 7... Cavity, 9...・Mandrel. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] (1) Formed by biaxial stretch blow molding of a multilayer plastic parison, the inner and outer surface layers are heated at a temperature of 23°C and 7 x 10^7 dyne.
/cm^2 stress, the sum of the initial elastic modulus and delayed elastic modulus is 1 x 10^1^0 dyne/cm^2 or less, the steady flow viscosity is 1 x 10^1^7 poise or more, and It is made of a thermoplastic resin with a delay time of 6 x 10^6 seconds or less, and the intermediate layer is made of multiple types of resins with a solubility index of 9.5 or more, and at least one of the resins has an oxygen permeability coefficient of 5 x 10^.
-^1^1cc・cm/cm^2・sec・cmHg or less, the difference in solubility index between each resin is 4.5 or less, and the blend has a higher elongation rate than the arithmetic average elongation rate of the resin components. A hollow container comprising: a polyester containing ethylene terephthalate units as a main component;
The composition consists of a blend containing a polyamide or the like consisting of an aromatic group-containing component in a weight ratio of 5:95 to 85:15, and the inner and outer surface layers are composed of a polyester mainly composed of ethylene terephthalate units. Features a hollow container.