JP2004351927A - Multilayered container - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayered container allowing wider design freedom, nearly free from peeling due to a fall or impact and without the need for forming a shape having as little unevenness and bending as possible for the prevention of peeling. <P>SOLUTION: The multilayered container comprises an outermost layer, an innermost layer and at least one intermediate layer between the outermost and innermost layers. The outermost and innermost layers are mainly composed of a thermoplastic polyester resin A obtained from the polymerization of a dicarboxylic acid component containing not less than 80 mol% of terephthalic acid and a diol component containing not less than 80 mol% of ethylene glycol. At least one layer of the intermediate layers is mainly composed of a polyamide resin C obtained from the polymerization of a diamine component containing not less than 70 mol% of methaxylene diamine and a dicarboxylic acid component containing not less than 70 mol% of an adipic acid and a mixture of resins B containing a polyamide resin D wherein the glass transition temperature is not higher than 130°C but higher than that of the polyamide resin C with the solubility index being greater than that of the thermoplastic polyester resin A and lower than that of the polyamide resin C. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to the prevention of delamination of a multilayer container, and more specifically, to improve the interlayer adhesion between the innermost layer and the outermost layer and the intermediate layer when receiving an impact when transporting or dropping the multilayer container. The present invention relates to a multilayer container which can prevent delamination of a multilayer container and can avoid delamination without having a shape having a small number of uneven portions and bent portions, and has a large degree of freedom in design.

  At present, plastic containers (such as bottles) mainly composed of polyester such as polyethylene terephthalate (PET) are widely used for tea, fruit juice drinks, carbonated drinks and the like. The proportion of small plastic bottles in plastic containers is increasing year by year. Since the ratio of the surface area per unit volume increases as the bottle becomes smaller, the expiration date of the contents tends to be shorter when the bottle is made smaller. In addition, in recent years, beer that is easily affected by oxygen and light is sold in plastic bottles, and tea in plastic bottles is sold hot, and the range of use of plastic containers is expanding. Is required.

  In response to the above requirements, as a method for imparting gas barrier properties to bottles, carbon coat, vapor deposition, and application of barrier resin are applied to multilayer bottles, blend bottles, and thermoplastic polyester resin single-layer bottles using thermoplastic polyester resin and gas barrier resin. Barrier-coated bottles and the like have been developed.

  As an example of a multi-layer bottle, a thermoplastic resin such as PET and a thermoplastic gas barrier resin such as polymetaxylylene adipamide (polyamide MXD6) which form the innermost layer and the outermost layer are injected to form a mold cavity. A bottle obtained by biaxially stretch-blow-molding a parison having a three-layer or five-layer structure obtained by filling has been put to practical use.

  Further, a resin having an oxygen capturing function of capturing oxygen in a container while blocking oxygen from outside the container has been developed and applied to a multilayer bottle. As the oxygen-scavenging bottle, a multilayer bottle using polyamide MXD6 mixed with a transition metal-based catalyst as a gas barrier layer is preferable in terms of oxygen absorption rate, transparency, strength, moldability, and the like.

  The multilayer bottle is used for containers for beer, tea, carbonated drinks, etc. due to its good gas barrier properties. By using the multilayer bottle for these applications, the quality of the content is maintained and the shelf life is improved.On the other hand, delamination occurs between different resins, for example, between the innermost layer and the outermost layer and the intermediate layer, and the product There is a problem that loses value.

As a method of improving such a problem, when a resin constituting the innermost layer and the outermost layer is finally injected into the mold cavity, a backflow adjusting device capable of causing a certain amount of backflow to the gas barrier layer side. It is disclosed to improve the delamination resistance by interposing a coarse mixed resin between layers used, but there is a problem that a special device is used (see Patent Document 1).
JP 2000-254963 A

  An object of the present invention is to solve the above problems, and in a multilayer container, peeling due to drop or impact hardly occurs, and in order to prevent peeling, it is not necessary to make the shape with few irregularities and bent parts, and the degree of design freedom is small. It is to provide a large multilayer container.

  The present inventors have conducted intensive studies on the delamination resistance of the multilayer container, and as a result, increased the affinity between the resin constituting the innermost layer and the outermost layer and the resin constituting the intermediate layer, and have a high glass transition temperature. It has been found that by blending a resin, the adhesion between layers is improved, and delamination at the time of dropping or the like can be prevented. That is, by bringing the solubility index of the resin constituting the intermediate layer close to the solubility index of the resin constituting the innermost layer and the outermost layer, and further increasing the strain after blow molding of the resin constituting the intermediate layer, delamination is suppressed. The present inventors have found that a multilayered container is obtained, and arrived at the present invention.

That is, the present invention provides a multilayer container comprising an outermost layer, an innermost layer, and at least one intermediate layer located between the outermost layer and the innermost layer, wherein the outermost layer and the innermost layer contain 80 mol% of terephthalic acid. It is mainly composed of a thermoplastic polyester resin A obtained by polymerizing a dicarboxylic acid component containing above and a diol component containing ethylene glycol of 80 mol% or more, and at least one of the intermediate layers contains meta-xylylenediamine of 70 mol% or more. A polyamide resin C obtained by polymerizing a diamine component and a dicarboxylic acid component containing at least 70 mol% of adipic acid with the following formula (1):
Sa <Sd <Sc (1)
(Wherein, Sa is the solubility index of the thermoplastic polyester resin A, Sc is the solubility index of the polyamide resin C, Sd is the solubility index of the polyamide resin D, and each solubility index is calculated by the Small method). Mainly composed of a mixed resin B containing a polyamide resin D in a weight ratio of 99.5 / 0.5 to 80/20, wherein the glass transition temperature of the polyamide resin D is higher than the glass transition temperature of the polyamide resin C; , 130 ° C. or lower.
Furthermore, the present invention uses an injection molding machine having a skin-side injection cylinder and a core-side injection cylinder to form an outermost layer, an innermost layer, and at least one intermediate layer located between the outermost layer and the innermost layer. A thermoplastic polyester resin obtained by polymerizing a dicarboxylic acid component containing at least 80 mol% of terephthalic acid and a diol component containing at least 80 mol% of ethylene glycol from the skin-side injection cylinder. A is injected to form the innermost layer and the outermost layer, and a diamine component containing at least 70 mol% of metaxylylenediamine and a dicarboxylic acid component containing at least 70 mol% of adipic acid are polymerized from the injection cylinder on the core side. And the following formula (1):
Sa <Sd <Sc (1)
(In the formula, Sa is the solubility index of the thermoplastic polyester resin A, Sc is the solubility index of the polyamide resin C, Sd is the solubility index of the polyamide resin D, and each solubility index is calculated by the Small method.)
Producing a multilayer parison by injecting a mixed resin B containing a polyamide resin D satisfying the above at a weight ratio of 99.5 / 0.5 to 80/20 to form at least one of the intermediate layers. And a method for producing a multilayer container characterized by the following.

  ADVANTAGE OF THE INVENTION According to this invention, the delamination does not easily occur and a multilayer container excellent in gas barrier properties can be obtained, and the industrial significance of the present invention is great.

  The thermoplastic polyester resin A (hereinafter, abbreviated as “polyester resin A”) which may form at least one of the outermost layer, the innermost layer, and in some cases, the intermediate layer of the multilayer container of the present invention is 80 mol%. As described above, a polyester obtained by a polymerization reaction of a dicarboxylic acid component having preferably 90 mol% or more of terephthalic acid and a diol component having 80 mol% or more, preferably 90 mol% or more of ethylene glycol.

  As the polyester resin A, polyethylene terephthalate is preferably used. Polyethylene terephthalate can exhibit excellent properties in all of transparency, mechanical strength, injection moldability, and stretch blow moldability.

  Other dicarboxylic acid components other than terephthalic acid include isophthalic acid, diphenyl ether-4,4-dicarboxylic acid, naphthalene-1,4 or 2,6-dicarboxylic acid, adipic acid, sebacic acid, decane-1,10-carboxylic acid. An acid, hexahydroterephthalic acid, can be used. Other diol components other than ethylene glycol include propylene glycol, 1,4-butanediol, neopentyl glycol, diethylene glycol, cyclohexanedimethanol, 2,2-bis (4-hydroxyphenyl) propane, and 2,2-bis ( 4-Hydroxyethoxyphenyl) propane and the like can be used. Further, an oxyacid such as p-oxybenzoic acid can be used as a raw material monomer of the polyester resin A.

  The intrinsic viscosity of the polyester resin A is 0.55 to 1.50, preferably 0.65 to 1.40. When the intrinsic viscosity is 0.55 or more, the multilayer parison can be obtained in a transparent amorphous state, and the obtained multilayer container also satisfies the mechanical strength. When the intrinsic viscosity is 1.50 or less, it is possible to avoid molding problems due to an increase in viscosity.

  Further, other thermoplastic resins can be used in combination with the polyester resin A as long as the characteristics of the present invention are not impaired. Examples of other thermoplastic resins include thermoplastic polyester resins such as polyethylene-2,6-naphthalenedicarboxylate, polyolefin resins, polycarbonate, polyacrylonitrile, polyvinyl chloride, and polystyrene. The blending amount of the other thermoplastic resin is preferably 10% by weight or less of the polyester resin A.

At least one of the intermediate layers of the multilayer container of the present invention is formed of a mixed resin B of the following polyamide resin C and polyamide resin D.
The polyamide resin C is obtained by polymerizing a diamine component containing at least 70 mol% of meta-xylylenediamine and a dicarboxylic acid component containing at least 70 mol% of adipic acid. When the amount of meta-xylylenediamine in the diamine component is 70 mol% or more, excellent gas barrier properties can be maintained. When the adipic acid content in the dicarboxylic acid component is 70 mol% or more, a decrease in gas barrier properties and a decrease in crystallinity can be prevented.

  Polymetaxylylene adipamide (polyamide MXD6) is preferably used as polyamide resin C because it exhibits excellent properties in co-injection moldability and co-stretch blow moldability with polyester resin A (polyethylene terephthalate). .

  As diamine components that can be used other than meta-xylylenediamine, tetramethylene diamine, pentamethylene diamine, 2-methylpentanediamine, hexamethylene diamine, heptamethylene diamine, octamethylene diamine, nonamethylene diamine, decamethylene diamine, dodecamethylene diamine, Aliphatic diamines such as 2,2,4-trimethylhexamethylenediamine and 2,4,4-trimethylhexamethylenediamine; 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, 2,3-diaminocyclohexane, 1,4-diaminocyclohexane, bis (4-aminocyclohexyl) methane, 2,2-bis (4-aminocyclohexyl) propane, bis (aminomethyl) decalin, bis (amido) Alicyclic diamines such as methyl) tricyclodecane; diamines having an aromatic ring such as bis (4-aminophenyl) ether, paraphenylenediamine, paraxylylenediamine, and bis (aminomethyl) naphthalene; It is not limited to these.

Examples of the dicarboxylic acid component that can be used other than adipic acid include suberic acid, azelaic acid, sebacic acid, 1,10-decanedicarboxylic acid, terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid, but are not limited thereto. It is not done.
Further, the polyamide resin C may contain a small amount of a monoamine or a monocarboxylic acid used as a molecular weight regulator at the time of production.

The above polyamide resin C is produced by melt polycondensation of a diamine component and a dicarboxylic acid component or by solid phase polymerization after melt polycondensation.
As the melt polycondensation method, for example, there is a method in which a nylon salt composed of metaxylylenediamine and adipic acid is heated in the presence of water under pressure and polymerized in a molten state while removing added water and condensed water. . It is also produced by a method in which meta-xylylenediamine is directly added to adipic acid in a molten state and polycondensed. In this case, in order to keep the reaction system in a uniform liquid state, meta-xylylenediamine is continuously added to adipic acid, and during this time, the reaction system is raised so that the reaction temperature does not fall below the melting points of the resulting oligoamide and polyamide. While heating, the polycondensation proceeds.

  The relative viscosity of a polyamide having a relatively low molecular weight obtained by melt polycondensation (a value obtained by dissolving 1 g of a polyamide resin in 100 ml of 96% sulfuric acid and measuring at 25 ° C., the same applies hereinafter) is usually about 2.28. When the relative viscosity after the melt polycondensation is 2.28 or less, a high-quality polyamide having a low color tone and a good color tone can be obtained. The relatively low molecular weight polyamide obtained by melt polycondensation may then be subjected to solid state polymerization. Solid phase polymerization is a process in which a polyamide having a relatively low molecular weight obtained by melt polycondensation is pelletized or powdered, and heated to a temperature of 150 ° C. or higher and a temperature lower than the melting point of the polyamide under reduced pressure or an inert gas atmosphere. It is implemented by doing. The relative viscosity of the solid-phase polymerized polyamide is preferably 2.3 to 4.2. Within this range, the hollow container, film, and sheet can be formed into a good shape, and the resulting hollow container, film, and sheet have good performance, particularly good mechanical performance. Although some effects of the present invention can be obtained by using a polyamide having a relatively low molecular weight after melt polycondensation, the mechanical strength, particularly the impact resistance, is not sufficient, and is not practical as a material for hollow containers.

The polyamide resin D is a resin satisfying the following formula (1).
Sa <Sd <Sc (1)
(In the formula, Sa is the solubility index of the thermoplastic polyester resin A, Sc is the solubility index of the polyamide resin C, and Sd is the solubility index of the polyamide resin D.)
The solubility index is calculated by the Small method (see Journal of the Adhesion Society of Japan, Vol. 22, No. 10, p. 51 (1986)).
It is important that the value of Sd of the polyamide resin D is between Sa and Sc in order to increase the affinity between the innermost and outermost layers (polyester resin A layer) and the intermediate layer (gas barrier layer). If Sd exceeds this range, the affinity between the polyester resin A constituting the innermost layer and the outermost layer and the mixed resin B constituting the intermediate layer will be low, and the adhesion between the layers will be reduced, which is not preferable for preventing delamination.
Such a polyamide resin D can be obtained by designing a skeleton segment in a polymer so as to satisfy the above formula (1) from the solubility index of the polyester resin A and the polyamide resin C obtained by calculation by the Small method. .

  The glass transition temperature of the polyamide resin D is higher than the glass transition temperature of the polyamide resin C and is 130 ° C. or less. If the glass transition temperature of the polyamide resin D is higher than the glass transition temperature of the polyamide resin C, the stress distortion of the polyamide resin B constituting the intermediate layer after blow molding becomes large, and the effect of relaxing the distortion prevents delamination. Is thought to improve. If the glass transition temperature of the polyamide resin D exceeds 130 ° C., the effect of preventing peeling is recognized, but molding of the multilayer container becomes difficult, which is not preferable.

  As described above, in the present invention, polyethylene terephthalate is preferably used as the polyester resin A because of its excellent transparency, mechanical strength, injection moldability, and stretch blow moldability. Further, polyamide MXD6 is suitably used as polyamide resin C because of its excellent co-injection moldability and co-stretch blow moldability with polyethylene terephthalate. When polyethylene terephthalate is used as the polyester resin A and polyamide MXD6 is used as the polyamide resin C, the polyamide resin D preferably contains a unit derived from an aromatic dicarboxylic acid, and the aromatic dicarboxylic acid is terephthalic acid and / or Those which are isophthalic acid are more preferred. Specific examples include nylon 6IT and nylon 6I6T (I represents isophthalic acid and T represents terephthalic acid), among which nylon 6IT is particularly preferred. As the polyamide resin D, a polyamide resin having a solubility index of 11 to 13 is preferable, and a polyamide resin having a solubility index of 12.0 to 12.9 is more preferable.

  The mixed resin B is a dry blending method in which the pellets of the polyamide resin C and the polyamide resin D are dry-mixed and re-pelletized by an injection molding machine hopper, or the polyamide resin C and the polyamide resin D are melt-extruded and re-pelletized. It can be produced by any of the following melt blending methods. It should be noted that an appropriate compounding recipe is selected according to the application, use conditions, mechanical performance, and the like.

  The weight ratio between the polyamide resin C and the polyamide resin D in the mixed resin B is 99.5 / 0.5 to 80/20, preferably 99/1 to 85/15, and more preferably 95/5 to 90/10. is there. If the weight ratio of the polyamide resin D is less than 0.5%, a remarkable effect of improving peel resistance cannot be obtained. When the weight ratio of the polyamide resin D exceeds 20%, the effect of improving the peeling resistance can be seen, but the good barrier property of the polyamide resin C does not contribute to the multilayer container and is not practical.

  The mixed resin B may contain a layered silicate. The layered silicate is a 2-octahedral or 3-octahedral layered silicate having a charge density of 0.25 to 0.6. Examples of the 2-octahedral type include montmorillonite and beidellite. Hectorite, savonite, etc. are mentioned as an octahedron type. Among these, montmorillonite is preferred.

  It is preferable that an organic swelling agent such as a polymer compound or an organic compound is brought into contact with the layered silicate in advance to expand the interlayer of the layered silicate. As the organic swelling agent, a quaternary ammonium salt can be preferably used, and more preferably, a quaternary ammonium salt having at least one alkyl group or alkenyl group having 12 or more carbon atoms is used.

  Specific examples of the organic swelling agent include trimethyl alkyl ammonium salts such as trimethyl dodecyl ammonium salt, trimethyl tetradecyl ammonium salt, trimethyl hexadecyl ammonium salt, trimethyl octadecyl ammonium salt and trimethyl eicosyl ammonium salt; trimethyl octadecenyl ammonium salt Triethylalkenyl ammonium salts such as trimethyl octadecadienylammonium salt; triethyl alkyl ammonium salts such as triethyl dodecyl ammonium salt, triethyl tetradecyl ammonium salt, triethyl hexadecyl ammonium salt, triethyl octadecyl ammonium salt; tributyl dodecyl ammonium salt, tributyl tetra Decyl ammonium salt, tributyl hexadecyl ammonium salt, Tributyl alkyl ammonium salts such as butyl octadecyl ammonium salt; dimethyl dialkyl ammonium salts such as dimethyl didodecyl ammonium salt, dimethyl ditetradecyl ammonium salt, dimethyl dihexadecyl ammonium salt, dimethyl dioctadecyl ammonium salt, dimethyl ditallow ammonium salt; dimethyl Dimethyldialkenyl ammonium salts such as dioctadecenyl ammonium salt and dimethyldioctadecadienylammonium salt; diethyldidodecylammonium salt, diethylditetradecylammonium salt, diethyldihexadecylammonium salt, diethyldioctadecylammonium salt and the like A diethyldialkylammonium salt; dibutyldidodecylammonium salt, dibutylditetradecylammonium salt, Dibutyl dialkyl ammonium salts such as butyl dihexadecyl ammonium salt and dibutyl dioctadecyl ammonium salt; methyl benzyl dialkyl ammonium salts such as methyl benzyl dihexadecyl ammonium salt; dibenzyl dialkyl ammonium salts such as dibenzyl dihexadecyl ammonium salt; Trialkylmethylammonium salts such as dodecylmethylammonium salt, tritetradecylmethylammonium salt and trioctadecylmethylammonium salt; trialkylethylammonium salts such as tridodecylethylammonium salt; trialkylbutylammonium salts such as tridodecylbutylammonium salt 4-amino-n-butyric acid, 6-amino-n-caproic acid, 8-aminocaprylic acid, 10-aminodecanoic acid, 12-amino Ω-amino acids such as dodecanoic acid, 14-aminotetradecanoic acid, 16-aminohexadecanoic acid and 18-aminooctadecanoic acid. Further, a hydroxyl group and / or an ether group-containing ammonium salt, in particular, methyl dihydroxyethyl hydrogenated tallow ammonium salt, and methyl dialkyl (PAG) ammonium salt, ethyl dialkyl (PAG) ammonium salt, butyl dialkyl (PAG) ammonium salt, Dimethylbis (PAG) ammonium salt, diethylbis (PAG) ammonium salt, dibutylbis (PAG) ammonium salt, methylalkylbis (PAG) ammonium salt, ethylalkylbis (PAG) ammonium salt, butylalkylbis (PAG) ammonium salt, methyltrimethylbis (PAG) ammonium salt (PAG) ammonium salt, ethyltri (PAG) ammonium salt, butyltri (PAG) ammonium salt, tetra (PAG) ammonium salt (where alkyl is dodecyl or tetradecyl) , Hexadecyl, octadecyl, eicosyl, etc., represents an alkyl group having 12 or more carbon atoms, and PAG represents a polyalkylene glycol residue, preferably a polyethylene glycol residue or a polypropylene glycol residue having 20 or less carbon atoms. A quaternary ammonium salt containing an alkylene glycol residue of can also be used as an organic swelling agent. Among them, trimethyl dodecyl ammonium salt, trimethyl tetradecyl ammonium salt, trimethyl hexadecyl ammonium salt, trimethyl octadecyl ammonium salt, dimethyl didodecyl ammonium salt, dimethyl ditetradecyl ammonium salt, dimethyl dihexadecyl ammonium salt, dimethyl dioctadecyl ammonium salt, dimethyl dioctadecyl ammonium salt, dimethyl Ditallow ammonium salts and methyldihydroxyethyl hydrogenated tallow ammonium salts are preferred. In addition, these organic swelling agents can be used alone or as a mixture of plural kinds.

  The compounding ratio of the layered silicate treated with the organic swelling agent in the mixed resin B is preferably 0.5 to 8% by weight, more preferably 1.5 to 5% by weight based on the total amount of the polyamide resin C and the polyamide resin D. Is more preferred. When the mixing ratio of the layered silicate treated with the organic swelling agent is within the above range, the effect of improving the gas barrier properties of carbon dioxide, oxygen and the like can be obtained, and the transparency is not impaired.

  It is preferable that the layered silicate treated with the organic swelling agent is uniformly dispersed in the mixed resin B without local aggregation. The term “uniform dispersion” as used herein means that the layered silicate is separated into a plate shape in the mixed resin B, and 50% or more of them has an interlayer distance of 5 nm or more. Here, the interlayer distance refers to the distance between the centers of gravity of the flat objects. The greater the distance, the better the dispersion state, the better the appearance such as the transparency of the molded product, and the better the barrier property against gaseous substances such as oxygen and carbon dioxide.

  The method for dispersing the layered silicate treated with the organic swelling agent in the mixed resin B is not particularly limited. For example, a method of adding and stirring a layered silicate treated with an organic swelling agent during polycondensation for the production of polyamide resin C and / or polyamide resin D, and various commonly used methods such as a single screw or twin screw extruder A known method such as a method of melting and kneading the layered silicate treated with the polyamide resin C and / or the polyamide resin D and the organic swelling agent using an extruder can be used. Among these, a method of melt-kneading using a twin-screw extruder is a preferred method in the present invention.

  When melt-kneading using a twin-screw extruder, it is preferable to set the melt-kneading temperature in the range from the vicinity of the melting point of the polyamide resin to the melting point + 60 ° C. so as to minimize the residence time of the resin in the extruder. In addition, the screw installed in the extruder is provided with a part for mixing the layered silicate treated with the polyamide resin and the organic swelling agent, and this part is combined with parts such as a reverse screw element and a kneading disk. The use of such a material facilitates efficient dispersion of the layered silicate.

  In the melt kneading method, if the melt viscosity of the polyamide resin C or D is too low, the layered silicate is difficult to disperse, aggregates thereof are easily generated, and the appearance is impaired when molded. If the melt viscosity is too high, a special device may be required when performing melt kneading. By appropriately controlling the melt viscosity (for example, controlling the melt viscosity of the polyamide resin C to 200 to 1000 Pa · s and the melt viscosity of the polyamide resin D to 100 to 900 Pa · s), an appropriate pressure is applied to the resin during extrusion kneading. However, the dispersibility of the layered silicate is improved, and the silicate is easily formed at the time of injection molding or extrusion molding.

  The moisture content of the polyamide resin C and the polyamide resin D is preferably less than 0.2%. When the water content is 0.2% or more, not only does the dispersibility of the layered silicate treated with the organic swelling agent during melt-kneading decrease, but also the molecular weight of the polyamide resin significantly decreases, or the molded product becomes gel-like. It is not preferable because a product is easily generated.

  The mixed resin B may include one or more metal elements selected from transition metals of Group VIII of the periodic table, manganese, copper, and zinc. By containing the metal element, the oxidation of the mixed resin B is promoted, and the oxygen absorbing function is exhibited.

  The metal element is preferably added to the polyamide resin C and the polyamide resin D as an inorganic acid salt, an organic acid salt or a complex salt having a low acid value of the metal element (hereinafter collectively referred to as a metal catalyst compound). Examples of the inorganic acid salts include halides such as chlorides and bromides, sulfates, nitrates, phosphates, silicates, and the like. Examples of the organic acid salt include carboxylate, sulfonate, phosphonate and the like. Examples of the complex salt include a transition metal complex with β-diketone, β-keto acid ester and the like. Since the oxygen absorbing function is good, it is preferable to use a carboxylate, halide or acetylacetonate complex of the metal element, and it is more preferable to use a stearate, acetate or acetylacetonate complex. Further, cobalt is preferable as the metal element because it is particularly excellent in the oxygen absorbing function. One or more kinds of the metal catalyst compounds can be added.

  The addition amount of the metal element is preferably 0.01 to 0.10% by weight, more preferably 0.02 to 0.08% by weight, based on the total amount of the polyamide resin C and the polyamide resin D. When the addition amount is less than 0.01% by weight, the oxygen absorbing function is not sufficiently exhibited, and the effect of improving the oxygen barrier property of the multilayer container is reduced. Further, even if added in an amount of more than 0.10% by weight, the oxygen barrier effect of the multilayer container is not further improved, which is uneconomical.

  In the multilayer container of the present invention, a portion having a low draw ratio (1 to 2.5 times) may be generated depending on the shape of the parison and the container. When the intermediate layer in the low stretch ratio portion absorbs water, it may be whitened. If necessary, by adding a whitening inhibitor to the mixed resin B, whitening is suppressed and a multilayer container having good transparency can be obtained.

  The anti-whitening agent used in the present invention is a fatty acid metal salt having 18 to 50 carbon atoms, preferably 18 to 34 carbon atoms. Prevention of whitening can be expected with 18 or more carbon atoms. When the carbon number is 50 or less, the uniform dispersion in the mixed resin B becomes good. The fatty acid may have a side chain or a double bond, but may be a linear saturated fatty acid such as stearic acid (C18), eicosanoic acid (C20), behenic acid (C22), montanic acid (C28), and triacontanic acid (C30). Fatty acids are preferred. There is no particular limitation on the metal forming a salt with the fatty acid, but sodium, potassium, lithium, calcium, barium, magnesium, strontium, aluminum, zinc and the like are exemplified, and sodium, potassium, lithium, calcium, aluminum, and zinc are particularly preferable. preferable.

  The fatty acid metal salts may be used alone or in combination of two or more. In the present invention, the particle size of the fatty acid metal salt is not particularly limited, but the smaller the particle size, the easier it is to disperse uniformly in the mixed resin B, so the particle size is preferably 0.2 mm or less.

  The amount of the fatty acid metal salt to be added is preferably 0.005 to 1.0 part by weight, more preferably 0.05 to 0.5 part by weight, and particularly preferably 0.05 to 0.5 part by weight, based on 100 parts by weight of the total amount of the polyamide resin C and the polyamide resin D. Preferably it is 0.12-0.5 weight part. By adding 0.005 parts by weight or more to the total amount of 100 parts by weight, a whitening preventing effect can be expected. Further, when the added amount is 1.0 part by weight or less with respect to the total amount of 100 parts by weight, it is possible to keep the haze value of the obtained multilayer container low.

  Instead of the fatty acid metal salt, a compound selected from the following diamide compounds and diester compounds may be added as a whitening inhibitor. One or two or more diamide compounds may be added, one or two or more diester compounds may be added, and one or two or more diamide compounds and one or two or more diamide compounds may be added. May be used in combination.

  The diamide compound is obtained from a fatty acid having 8 to 30 carbon atoms and a diamine having 2 to 10 carbon atoms. When the fatty acid has 8 or more carbon atoms and the diamine has 2 or more carbon atoms, a whitening preventing effect can be expected. When the fatty acid has 30 or less carbon atoms and the diamine has 10 or less carbon atoms, the uniform dispersion in the mixed resin B is good. Fatty acids may have side chains or double bonds, but straight-chain saturated fatty acids are preferred.

Examples of the fatty acid component of the diamide compound include stearic acid (C18), eicosanoic acid (C20), behenic acid (C22), montanic acid (C28), and triacontanic acid (C30). Examples of the diamine component of the diamide compound include ethylenediamine, butylenediamine, hexanediamine, xylylenediamine, and bis (aminomethyl) cyclohexane. A diamide compound obtained by combining these is used in the present invention. A diamide compound obtained from a fatty acid having 8 to 30 carbon atoms and a diamine mainly composed of ethylenediamine, or a diamide compound obtained mainly from a fatty acid mainly composed of montanic acid and a diamine having 2 to 10 carbon atoms is preferable.
The diester compound is obtained from a fatty acid having 8 to 30 carbon atoms and a diol having 2 to 10 carbon atoms. When the fatty acid has 8 or more carbon atoms and the diol has 2 or more carbon atoms, an anti-whitening effect can be expected. When the fatty acid has 30 or less carbon atoms and the diol has 10 or less carbon atoms, the uniform dispersion in the mixed resin B is good. Fatty acids may have side chains or double bonds, but straight-chain saturated fatty acids are preferred.

  Examples of the fatty acid component of the diester compound include stearic acid (C18), eicoic acid (C20), behenic acid (C22), montanic acid (C28), and triacontanic acid (C30). Examples of the diol component of the diester compound include ethylene glycol, propanediol, butanediol, hexanediol, xylylene glycol, and cyclohexanedimethanol. A diester compound obtained by combining these is used in the present invention. Diester compounds obtained mainly from fatty acids mainly consisting of montanic acid and diols mainly consisting of ethylene glycol and / or 1,3-butanediol are particularly preferred.

  The addition amount of the diamide compound and / or the diester compound is preferably 0.005 to 1.0 part by weight, more preferably 0.05 to 0.5 part by weight, based on 100 parts by weight of the total amount of the polyamide resin C and the polyamide resin D. Parts by weight, particularly preferably 0.12 to 0.5 parts by weight. By adding 0.005 parts by weight or more to the total amount of 100 parts by weight, a whitening preventing effect can be expected. When the added amount is 1.0 part by weight or less based on 100 parts by weight in total, it is possible to keep the haze value of the obtained multilayer container low.

  A conventionally known mixing method can be applied to the addition of the whitening inhibitor to the mixed resin B. For example, pellets of the polyamide resins C and D, a metal catalyst compound, and a whitening inhibitor may be charged and mixed in a rotating hollow container. Also, after producing a polyamide resin composition containing a high concentration of anti-whitening agent, diluted with polyamide resin pellets containing no anti-whitening agent at a predetermined concentration, a method of melt-kneading this, after melt-blending, and subsequently And a method of molding by injection molding or the like.

  When the whitening inhibitor is used, it is possible to prevent the intermediate layer made of the mixed resin B from whitening immediately after the production of the multilayer container. Further, it is possible to prevent the intermediate layer made of the mixed resin B from being whitened after the multilayer container is stored for a long time under the condition that the whitening does not occur or the whitening does not increase. That is, after the container is not whitened without adding a whitening inhibitor or does not increase whitening, for example, after long-term storage in an atmosphere at a temperature of 23 ° C. and a humidity of 50% RH, the multilayer container is exposed to high humidity, water or boiling water. , Or heating above the glass transition temperature suppresses whitening in the same manner as immediately after molding.

  The multilayer container of the present invention uses an injection molding machine having two injection cylinders, and molds the polyester resin A and the mixed resin B having gas barrier properties from the injection cylinders on the skin side and the core side through a mold hot runner and a mold. The multilayer parison obtained by injecting into the cavity is further obtained by biaxially stretch blow molding. The blow molding of the multilayer parison may be performed by a conventionally known method. For example, a method of heating the surface of the multilayer parison to 80 to 120 ° C. followed by blow molding, crystallizing the mouth of the multilayer parison, and forming the surface of the multilayer parison to 80 to 120 A method of heating to 90 ° C. and then blow molding in a mold at 90 to 150 ° C. is employed. The blow pressure is usually 2 to 4 MPa.

  In the step of injecting the polyester resin A constituting the innermost layer and the outermost layer from the skin side injection cylinder and injecting the mixed resin B constituting the intermediate layer from the core side injection cylinder, first inject the polyester resin A, and then mix The resin B and the polyester resin A are simultaneously injected, and then the required amount of the polyester resin A is injected to fill the mold cavity, thereby forming a multilayer parison having a three-layer structure (polyester resin A / mixed resin B / polyester resin A). Can be manufactured.

  In the step of injecting the polyester resin A constituting the innermost layer and the outermost layer from the skin-side injection cylinder and injecting the mixed resin B constituting the intermediate layer from the core-side injection cylinder, first inject the polyester resin A, then the mixed resin B alone is injected, and finally polyester resin A is injected to fill the mold cavity, thereby forming a five-layer structure (polyester resin A / mixed resin B / polyester resin A / mixed resin B / polyester resin A). Multi-layer parisons can be manufactured. The method for producing the multilayer parison is not limited to the above method.

  In the multilayer container, the thickness of the layer made of the polyester resin A is preferably 0.01 to 1.0 mm, and the thickness of the layer made of the mixed resin B is preferably 0.005 to 0.2 mm. . Further, the thickness of the multilayer container does not need to be constant throughout the container, and is generally in the range of 0.2 to 1.0 mm.

  In a multilayer container obtained by biaxially stretch-blow-molding a multilayer parison, gas barrier properties can be exhibited if at least an intermediate layer made of the mixed resin B is present in the body of the multilayer container. The gas barrier performance is better when the intermediate layer extends to the vicinity.

  In the multilayer container of the present invention, the weight of the layer made of the mixed resin B is preferably 1 to 20% by weight, more preferably 2 to 15% by weight, based on the total weight of the multilayer container. If the weight of the layer made of the mixed resin B is less than 1% by weight, the gas barrier properties of the multilayer container may be insufficient, which is not preferable. On the other hand, if the weight of the layer composed of the mixed resin B is more than 20% by weight, it may be difficult to mold the multilayer parison as a precursor into a multilayer container, which is not preferable.

  In the multilayer container of the present invention, delamination due to drop or impact hardly occurs. In addition, since delamination hardly occurs even in a shape including an uneven portion and a bent portion, the shape of the multilayer container is not limited to a shape having few uneven portions and bent portions, and the degree of freedom in design is increased. The multilayer container of the present invention includes, for example, liquid beverages such as carbonated beverages, juices, water, milk, sake, whiskey, shochu, coffee, tea, jelly beverages, health beverages, seasonings, sauces, soy sauce, dressings, liquid soups, and the like. It is suitable for storing and storing various articles such as liquid seasonings, liquid foods such as liquid soups, liquid medicines, lotions, lotions, hair styling agents, hair dyes, shampoos and the like.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. The method for measuring the characteristics measured in the examples and the like will be described below.
(1) Intrinsic viscosity [η] of polyethylene terephthalate: A mixed solvent of phenol / tetrachloroethane = 6/4 (weight ratio) is used. Measurement temperature 30 ° C.
(2) Relative viscosity [η _rel ] of polyamide MXD6: 1 g of resin / 100 ml of 96% sulfuric acid, measurement temperature 25 ° C.
(3) Calculation of solubility index: Calculated by the Small method (see Journal of the Adhesion Society of Japan, Vol. 22, No. 10, p. 51 (1986)).
(4) Glass transition temperature: measured by a heat flux differential scanning calorimeter (model: DSC-50) manufactured by Shimadzu Corporation. Heating rate 10 ° C / min
(5) Haze value: Measured with a haze value measuring device (model: COH-300A) manufactured by Nippon Denshoku Industries Co., Ltd. according to JIS K-7105 and ASTM D1003.
(6) Delamination property: evaluated by a drop test of a container.
Drop test method: After the multilayer container was filled with water and capped, the multilayer container left standing for 24 hours was dropped, and the presence or absence of delamination was visually determined. The multilayer container was dropped vertically so that the bottom contacted the floor. Fall height 75cm. The delamination property was evaluated by the number of delaminated bottles when 50 bottles were dropped.
(7) Oxygen permeability of multilayer container: Measured according to ASTM D3985 in an atmosphere of 23 ° C., relative humidity of 100% inside the multilayer container, and 50% relative humidity outside. For the measurement, OX-TRAN 10 / 50A manufactured by Modern Controls was used.

The multilayer containers used in Examples 1 to 5 and Comparative Examples 1 and 2 were manufactured by the following method.
Three-layer parison shape: total length 95 mm, outer diameter 22 mm, wall thickness 4.2 mm. For the production of the three-layer parison, an injection molding machine (model: M200, four pieces) manufactured by Meiki Seisakusho Co., Ltd. was used.
Three-layer parison molding conditions Skin-side injection cylinder temperature: 280 ° C
Core side injection cylinder temperature: 260 ° C
Resin channel temperature in mold: 280 ° C
Mold cooling water temperature: 15 ° C
Ratio of mixed resin B in parison: 8% by weight
Multilayer container shape: total length 223 mm, outer diameter 65 mm, inner volume 500 ml, polyester resin A layer / mixed resin B layer / polyester resin A layer = 0.28 mm / 0.056 mm / 0.10 mm, bottom shape is champagne type. For the biaxial stretch blow molding, a blow molding machine (Model: LB-01, manufactured by KRUPP CORPLAST) was used.
Biaxial stretch blow molding conditions Parison heating temperature: 100 ° C
Blow pressure: 2.7 MPa

<Example 1>
The following materials were used to form a three-layered multilayer container.
Innermost layer and outermost layer Polyester resin A: polyethylene terephthalate having an intrinsic viscosity of 0.75 (RT543C manufactured by Nippon Unipet). The solubility index is 11.1.
Intermediate layer Mixed resin B: 90/10 (weight ratio) dry blend of polyamide resin C and polyamide resin D Polyamide resin C: polyamide MXD6 having a relative viscosity of 2.70 (MX nylon S6007 manufactured by Mitsubishi Gas Chemical). The solubility index is 13.0 and the glass transition temperature is 80 ° C.
Polyamide resin D: Nylon 6IT (Selar PA 3426 manufactured by DuPont-Mitsui Polychemicals). The solubility index is 12.6 and the glass transition temperature is 125 ° C.
Table 1 shows the evaluation results of the delamination property.

<Example 2>
A three-layered multilayer container was molded in the same manner as in Example 1 except that the polyamide resin C and the polyamide resin D were mixed at a ratio of 95/5 (weight ratio). Table 1 shows the results of evaluating the delamination property of the obtained three-layer container.

<Example 3>
A three-layered multilayer container was molded in the same manner as in Example 1 except that the polyamide resin C and the polyamide resin D were mixed at a ratio of 99/1 (weight ratio). Table 1 shows the evaluation results of the delamination property of the obtained three-layer container.

<Comparative Example 1>
A multilayer container having a three-layer structure was formed in the same manner as in Example 1 except that the polyamide resin D was not used and the intermediate layer was formed of the polyamide resin C alone. Table 1 shows the evaluation results of the delamination property of the obtained three-layer container.

<Example 4>
Layered silicate ("Kunipia" manufactured by Kunimine Industries) treated with polyamide MXD6 having a relative viscosity of 2.70 (MX Nylon S6007 manufactured by Mitsubishi Gas Chemical) and an organic swelling agent, containing 30% by weight of octadecyl ammonium as an organic swelling agent Layered silicate) was dry-blended at 97/3 (weight ratio). The obtained mixture is supplied at a rate of 6 kg / hr to a co-rotating twin-screw extruder having a cylinder diameter of 20 mm and having a screw having a retaining portion by an inverse element, and is melt-kneaded at a cylinder temperature of 270 ° C. The mixture was extruded from an extruder head into a strand, cooled, and pelletized. A multilayer container having a three-layer structure was formed in the same manner as in Example 2 except that this was used as the polyamide resin C. Table 2 shows the evaluation results of the oxygen permeability and the delamination property of the obtained three-layer container.

<Example 5>
The polyamide MXD6 having a relative viscosity of 2.70 (MX Nylon S6007 manufactured by Mitsubishi Gas Chemical) and cobalt stearate were dry-blended at a ratio of 99.5 / 0.5 (weight ratio). The mixture was melt-kneaded under the conditions, extruded from an extruder head into a strand, cooled, and pelletized. A multilayer container having a three-layer structure was molded in the same manner as in Example 2 except that this was used as the polyamide resin C. Table 2 shows the evaluation results of the oxygen permeability and the delamination property of the obtained three-layer container.

<Comparative Example 2>
The oxygen permeability of the three-layer container molded in Comparative Example 1 was measured. Table 2 shows the results.

<Example 6>
When mixing the polyamide resin C and the polyamide resin D, 0.2 parts by weight of sodium montanate (trade name: Hostamont NaV101, manufactured by Clariant Japan KK) was added as a whitening inhibitor to 100 parts by weight of the total amount of the polyamide resin. A three-layered multilayer container was formed in the same manner as in Example 1 except that the shape of the container was changed as described below.
Multilayer container shape: total length 170mm, volume 330ml, neck diameter 25mm, trunk diameter 66mm, polyester resin A layer / mixed resin B layer / polyester resin A layer = 0.33mm / 0.066mm / 0.12mm, bottom shape is champagne type .
After the evaluation results of the delamination property of the obtained three-layer container and the three-layer container filled with 330 ml of water were stored at 40 ° C./80% RH for 6 months, a low stretch ratio portion (stretch ratio of 1) of the container was used. Table 3 shows the results of measuring the haze value of the intermediate layer taken out from the sample (〜1.5 times).

<Example 7>
A multilayer container having a three-layer structure was formed in the same manner as in Example 6 except that the whitening inhibitor was changed to ethylene bisstearylamide (trade name: Alflow H-50T, manufactured by NOF Corporation).
Table 3 shows the evaluation results obtained in the same manner as in Example 6.

<Comparative Example 3>
A three-layer multilayer container was molded in the same manner as in Example 6, except that the polyamide resin D was not used and the polyamide resin C was used alone for the intermediate layer. Table 3 shows the evaluation results obtained in the same manner as in Example 6.

Claims (14)

An outermost layer, an innermost layer, and a multilayer container comprising at least one intermediate layer located between the outermost layer and the innermost layer,
The outermost layer and the innermost layer are mainly constituted by a thermoplastic polyester resin A obtained by polymerizing a dicarboxylic acid component containing at least 80 mol% of terephthalic acid and a diol component containing at least 80 mol% of ethylene glycol,
At least one of the intermediate layers has a polyamide resin C obtained by polymerizing a diamine component containing at least 70 mol% of meta-xylylenediamine and a dicarboxylic acid component containing at least 70 mol% of adipic acid with the following formula (1):
Sa <Sd <Sc (1)
(In the formula, Sa is the solubility index of the thermoplastic polyester resin A, Sc is the solubility index of the polyamide resin C, Sd is the solubility index of the polyamide resin D, and each solubility index is calculated by the Small method.)
Mainly composed of a mixed resin B containing a polyamide resin D satisfying 99.5 / 0.5 to 80/20 in a weight ratio of:
A multilayer container, wherein the glass transition temperature of the polyamide resin D is higher than the glass transition temperature of the polyamide resin C and is 130 ° C. or less. Solid-state polymerization of the polyamide resin obtained by melt-polycondensing the polyamide resin C with a diamine component containing at least 70 mol% of metaxylylenediamine and a dicarboxylic acid component containing at least 70 mol% of adipic acid; The multilayer container according to claim 1, wherein the container is a solid-phase-polymerized polyamide resin obtained by the following method. 3. The multilayer container according to claim 1, wherein the polyamide resin D has a solubility index Sd of 11 to 13. The multilayer container according to any one of claims 1 to 3, wherein the polyamide resin D contains a unit derived from an aromatic dicarboxylic acid. The multilayer container according to claim 4, wherein the aromatic dicarboxylic acid is terephthalic acid and / or isophthalic acid. The mixed resin B further contains a layered silicate treated with an organic swelling agent in an amount of 0.5 to 8% by weight of the total amount of the polyamide resin C and the polyamide resin D. The multilayer container according to any one of the above. The mixed resin B further contains one or more metal elements selected from the group consisting of a transition metal belonging to Group VIII of the periodic table, manganese, copper, and zinc in an amount of 0.1% of the total amount of the polyamide resin C and the polyamide resin D. The multilayer container according to any one of claims 1 to 6, comprising 0.1 to 0.10% by weight. The mixed resin B further comprises 0.005 to 1.0 part by weight of a whitening inhibitor based on 100 parts by weight of the total amount of the polyamide resin C and the polyamide resin D. The multilayer container according to any one of the above. The multilayer container according to any one of claims 1 to 8, wherein the weight ratio of the mixed resin B to the total weight of the multilayer container is 1 to 20% by weight. Using an injection molding machine having a skin-side injection cylinder and a core-side injection cylinder, a multilayer container including an outermost layer, an innermost layer, and at least one intermediate layer located between the outermost layer and the innermost layer is manufactured. A thermoplastic polyester resin A obtained by polymerizing a dicarboxylic acid component containing at least 80 mol% of terephthalic acid and a diol component containing at least 80 mol% of ethylene glycol from the skin-side injection cylinder. A polyamide resin C obtained by forming the innermost layer and the outermost layer and polymerizing a diamine component containing 70% by mole or more of metaxylylenediamine and a dicarboxylic acid component containing 70% by mole or more of adipic acid from the core-side injection cylinder. And the following equation (1):
Sa <Sd <Sc (1)
(In the formula, Sa is the solubility index of the thermoplastic polyester resin A, Sc is the solubility index of the polyamide resin C, Sd is the solubility index of the polyamide resin D, and each solubility index is calculated by the Small method.)
Producing a multilayer parison by injecting a mixed resin B containing a polyamide resin D satisfying the above at a weight ratio of 99.5 / 0.5 to 80/20 to form at least one of the intermediate layers. A method for producing a multilayer container. The thermoplastic polyester resin A is injected from the skin-side injection cylinder, the mixed resin B is injected simultaneously from the core-side injection cylinder, the thermoplastic polyester resin A is injected from the skin-side injection cylinder, and then the thermoplastic polyester resin A is injected from the skin-side injection cylinder. The method for producing a multi-layer container according to claim 10, wherein a parison having a three-layer structure is produced by injecting the mold into the mold cavity. By injecting the thermoplastic polyester resin A from the skin side injection cylinder, injecting the mixed resin B from the core side injection cylinder, and then injecting the thermoplastic polyester resin A from the skin side injection cylinder to fill the mold cavity The method for producing a multilayer container according to claim 10, wherein a parison having a five-layer structure is produced. The method for producing a multilayer container according to any one of claims 10 to 12, further comprising a step of heating the parison surface to 80 to 120 ° C and then performing blow molding. The method according to any one of claims 10 to 12, further comprising a step of crystallizing a mouth portion of the parison, heating the surface to 80 to 120 ° C, and then performing blow molding in a mold at 90 to 150 ° C. Method for producing a multilayer container.