Multilayer bodies and multilayer containers

Abstract

To provide a multilayer body and a multilayer container having excellent oxygen barrier property, interlayer peeling resistance and transparency in a good balanced manner.SOLUTION: There is provided a multilayer body which has a layer containing a polyester resin and a layer containing a polyamide resin, wherein the polyamide resin is a copolymer containing a structural unit derived from a diamine and a structural unit derived from a dicarboxylic acid, in which 70 mol% or more of a structural unit derived from a diamine is derived from a xylylenediamine, 70 mol% or more of a structural unit derived from a dicarboxylic acid is derived from an α,ω-linear aliphatic dicarboxylic acid having 4 to 8 carbon atoms and an α,ω-linear aliphatic dicarboxylic acid having 9 to 12 carbon atoms.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a multilayer body and a multilayer container. [Background technology]

[0002] Conventionally, multilayer bodies and multilayer containers have been studied that use polyester resin as the resin constituting the outer and inner layers and have a barrier layer formed from a polyamide resin between the outer and inner layers (Patent Document 1, Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-169027 [Patent Document 2] Japanese Patent Application Publication No. 60-232952 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the inventors' investigations revealed that multilayer bodies and multilayer containers having outer and inner layers formed from polyester resins and a barrier layer (intermediate layer) formed from polyamide resins have poor oxygen barrier properties depending on the type of polyamide resin. On the other hand, when a polyamide resin (MXD6) composed of metaxylylenediamine and adipic acid is used as the polyamide resin, a multilayer body or multilayer container with excellent oxygen barrier properties can be obtained. However, when a barrier layer made of MXD6 is used, depending on the application, the interlayer delamination resistance may not necessarily be sufficient. Furthermore, depending on the application, better transparency may be required for the multilayer container. The present invention has been made to solve the above problems, and has as its object to provide a multilayer body and a multilayer container that are excellent in balance among oxygen barrier properties, delamination resistance, and transparency. [Means for solving the problem]

[0005] In light of the above-mentioned problems, the present inventors have conducted research and found that the above-mentioned problems can be solved by using metaxylylenediamine, an α,ω-linear aliphatic dicarboxylic acid having 4 to 8 carbon atoms, and an α,ω-linear aliphatic dicarboxylic acid having 9 to 12 carbon atoms in combination as raw material monomers for polyamide resin. Specifically, the above problems were solved by the following means. <1> A multilayer body having a layer containing a polyester resin and a layer containing a polyamide resin, wherein the polyamide resin contains structural units derived from a diamine and structural units derived from a dicarboxylic acid, and 70 mol % or more of the structural units derived from the diamine are derived from xylylenediamine, and 70 mol % or more of the structural units derived from the dicarboxylic acid are a copolymer derived from an α,ω-linear aliphatic dicarboxylic acid having 4 to 8 carbon atoms and an α,ω-linear aliphatic dicarboxylic acid having 9 to 12 carbon atoms. <2> 71.0 to 95.0 mol % of the structural units derived from the dicarboxylic acid are derived from an α,ω-linear aliphatic dicarboxylic acid having 4 to 8 carbon atoms, and 29.0 to 5.0 mol % are derived from an α,ω-linear aliphatic dicarboxylic acid having 9 to 12 carbon atoms. <1> The multilayer body according to claim 1. <3> 75.0 to 95.0 mol % of the structural units derived from the dicarboxylic acid are derived from an α,ω-linear aliphatic dicarboxylic acid having 4 to 8 carbon atoms, and 25.0 to 5.0 mol % are derived from an α,ω-linear aliphatic dicarboxylic acid having 9 to 12 carbon atoms. <1> The multilayer body according to claim 1. <4> The α,ω-linear aliphatic dicarboxylic acid having 4 to 8 carbon atoms includes adipic acid, and the α,ω-linear aliphatic dicarboxylic acid having 9 to 12 carbon atoms includes sebacic acid. <1> ~ <3> 10. The multilayer body according to any one of the preceding items. <5> 70 mol % or more of the structural units derived from the diamine are derived from metaxylylenediamine, <1> ~ <4> 10. The multilayer body according to any one of the preceding items. <6> the polyester resin comprises a diol-derived structural unit and a dicarboxylic acid-derived structural unit, and 70 mol % or more of the diol-derived structural units are derived from ethylene glycol, 60 to 99 mol % of the dicarboxylic acid-derived structural units are derived from at least one selected from terephthalic acid and its esters, and 40 to 1 mol % are derived from at least one selected from isophthalic acid and its esters; <1> ~ <5> 10. The multilayer body according to any one of the preceding items. <7> It is stretched, <1> ~ <6> 10. The multilayer body according to any one of the preceding items. <8> <1> ~ <7> A multilayer container comprising the multilayer body according to any one of the above items. [Effects of the Invention]

[0006] The present invention makes it possible to provide a multilayer body and a multilayer container that are excellent in balance among oxygen barrier properties, delamination resistance, and transparency. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic diagram showing a method for producing a multilayer container by cold parison molding. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, an embodiment for carrying out the present invention (hereinafter simply referred to as "the present embodiment") will be described in detail. Note that the present embodiment is an example for explaining the present invention, and the present invention is not limited to only this embodiment. In this specification, the symbol "to" is used to mean that the numerical values ​​before and after it are included as the lower limit and upper limit. In this specification, various physical properties and characteristic values ​​are those at 23°C unless otherwise specified. If the measurement methods, etc. described in the standards shown in this specification vary from year to year, they will be based on the standards in effect as of January 1, 2022, unless otherwise stated.

[0009] The multilayer body of the present embodiment has a layer containing a polyester resin (hereinafter, sometimes simply referred to as a "polyester resin layer") and a layer containing a polyamide resin (hereinafter, sometimes simply referred to as a "polyamide resin layer"), and is characterized in that the polyamide resin contains structural units derived from diamines and structural units derived from dicarboxylic acids, with 70 mol % or more of the structural units derived from diamines being derived from xylylenediamine, and 70 mol % or more of the structural units derived from dicarboxylic acids being a copolymer derived from an α,ω-straight-chain aliphatic dicarboxylic acid having 4 to 8 carbon atoms and an α,ω-straight-chain aliphatic dicarboxylic acid having 9 to 12 carbon atoms. By using such a constitution, a multilayer body or a multilayer container having a good balance of excellent oxygen barrier properties, delamination resistance, and transparency can be obtained, and further, a multilayer body or a multilayer container having excellent carbon dioxide barrier properties can be obtained. That is, a layer containing a polyamide resin composed of metaxylylenediamine and adipic acid has excellent oxygen barrier properties, but there is room for improvement in terms of delamination resistance and transparency depending on the application. As a result of investigations into this point, the present inventors have found that the above problem can be solved by using a combination of an α,ω-linear aliphatic dicarboxylic acid having 4 to 8 carbon atoms and an α,ω-linear aliphatic dicarboxylic acid having 9 to 12 carbon atoms as the dicarboxylic acid components constituting the polyamide resin. In particular, it is surprising that both delamination resistance and transparency can be significantly improved. The reason for the improved delamination resistance is presumed to be as follows. When molding a multilayer body, the polyester resin and polyamide resin are melted in separate cylinders and then injected separately to form a multilayer body. However, during injection molding, the interface between the polyester resin and the polyamide resin remains in a molten state as solidification progresses within the mold. In this embodiment, by using an α,ω-linear aliphatic dicarboxylic acid having 4 to 8 carbon atoms in combination with an α,ω-linear aliphatic dicarboxylic acid having 9 to 12 carbon atoms, the solidification proceeds slowly, allowing the polyester resin and the polyamide resin to interact more strongly. This is presumed to improve adhesion at the interface between the polyester resin and the polyamide resin, thereby improving delamination resistance. Furthermore, it is presumed that the slow solidification results in high adhesion at the interface between the polyester resin and the polyamide resin, suppressing roughness at the interface and further improving transparency.

[0010] <Layer containing polyester resin (polyester resin layer)> The multilayer body of the present embodiment has a layer containing a polyester resin (polyester resin layer). The polyester resin layer in this embodiment is mainly composed of a polyester resin. Here, "main component" means that the polyester resin is the component with the largest content among the components contained in the polyester resin layer, and preferably comprises 80% by mass or more of polyester resin, more preferably 90% by mass or more of polyester resin, even more preferably 95% by mass or more of polyester resin, and even more preferably 98% by mass or more of polyester resin. The polyester resin may contain only one type, or may contain two or more types. When two or more types are contained, the total amount is preferably in the above range.

[0011] The polyester resin used in this embodiment is preferably a polyester resin that contains structural units derived from a diol and structural units derived from a dicarboxylic acid, in which 70 mol % or more of the structural units derived from the diol are derived from ethylene glycol, and 60 mol % or more of the structural units derived from the dicarboxylic acid are derived from at least one selected from terephthalic acid and its esters (preferably terephthalic acid). The structural units derived from the diol preferably derive from ethylene glycol at 85 mol % or more, more preferably 90 mol % or more, even more preferably 95 mol % or more, and even more preferably 99 mol % or more. Furthermore, it is preferred that the structural units derived from the dicarboxylic acid are derived from at least one selected from terephthalic acid and its esters in an amount of preferably 70 mol % or more, more preferably 80 mol % or more, and even more preferably 90 mol % or more. The upper limit may be 100 mol %, and preferably 99 mol % or less.

[0012] Furthermore, in this embodiment, it is preferred that 60 to 99 mol% of the structural units derived from the dicarboxylic acid are derived from at least one selected from terephthalic acid and its esters (preferably terephthalic acid), and 40 to 1 mol% are derived from at least one selected from isophthalic acid and its esters (preferably isophthalic acid). By including structural units derived from at least one selected from isophthalic acid and its esters, crystallization of the polyester resin proceeds slowly, and solidification proceeds slowly. Therefore, it is presumed that the interaction with the polyamide resin contained in the polyamide resin layer becomes stronger, tending to improve interlayer delamination resistance. Furthermore, in this embodiment, the proportion of structural units derived from at least one selected from isophthalic acid and its esters in the structural units derived from the dicarboxylic acid is preferably 20 mol% or less, more preferably 15 mol% or less, even more preferably 10 mol% or less, and even more preferably 5 mol% or less.

[0013] The polyester resin used in this embodiment may further contain other structural units, such as structural units derived from 1,4-cyclohexanedimethanol, as structural units derived from diol. However, in this embodiment, it is preferred that ethylene glycol accounts for preferably 85 mol % or more, more preferably 90 mol % or more, even more preferably 95 mol % or more, and even more preferably 99 mol % or more of the structural units derived from diol. Furthermore, the polyester resin used in this embodiment may further contain other structural units, such as structural units derived from naphthalenedicarboxylic acid, as structural units derived from dicarboxylic acid. However, in this embodiment, it is preferable that preferably 85 mol % or more, more preferably 90 mol % or more, even more preferably 95 mol % or more, and even more preferably 99 mol % or more of the structural units derived from dicarboxylic acid are terephthalic acid, isophthalic acid, and their esters (preferably terephthalic acid and isophthalic acid).

[0014] In the polyester resin of the present embodiment, of all structural units excluding terminal groups, preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, still more preferably 95% by mass or more, even more preferably 98% by mass or more, and still more preferably 99% by mass or more are constituted by structural units derived from diols and dicarboxylic acids.

[0015] The polyester resin contained in the polyester resin layer may be a crystalline polyester resin having a definite melting point, or may be an amorphous polyester resin not having a definite melting point, but is preferably a crystalline polyester resin having a melting point. The melting point of the polyester resin in the present embodiment is preferably 150° C. or higher, more preferably 200° C. or higher, and even more preferably 220° C. or higher, and is preferably 300° C. or lower, more preferably 290° C. or lower, and even more preferably 280° C. or lower. The melting point is measured according to the method described in the examples below. In the present embodiment, when the polyester resin layer contains two or more kinds of polyester resins, the melting point of the polyester resin is the value obtained by multiplying the melting point of each polyester resin by the mass fraction.

[0016] The intrinsic viscosity of the polyester resin is preferably 0.30 dL / g or more, more preferably 0.40 dL / g or more, and even more preferably 0.60 dL / g or more, and is preferably 2.00 dL / g or less, more preferably 1.50 dL / g or less, even more preferably 1.00 dL / g or less, and even more preferably 0.90 dL / g or less. In the present embodiment, when the polyester resin layer contains two or more polyester resins, the intrinsic viscosity is the intrinsic viscosity of the polyester resin mixture.

[0017] Intrinsic viscosity is measured according to the following method. Polyester resin (pellets) is dissolved in a mixed solvent of phenol / 1,1,2,2-tetrachloroethane (1 / 1 by mass) by stirring at 110°C for 1 hour to a concentration of 1.00 g / dL. The solution is then cooled to 30°C. Using a fully automatic solution viscometer, the time it takes for the sample solution and the solvent alone to fall is measured at 30°C, and the intrinsic viscosity is calculated using the following formula (1). Intrinsic viscosity=((1+4K H η sp ) 0.5 -1) / (2K H C) …(1) where η sp =η / η0-1, where η is the time it takes for the sample solution to fall, η0 is the time it takes for the solvent alone to fall, C is the concentration of the sample solution (g / dL), and K H is Huggins' constant. K H will use 0.33.

[0018] In addition to the above, examples of polyester resins that can be referred to include the polyester resins described in paragraphs 0064 to 0080 of JP 2016-169027 A, the polyester resins described in paragraphs 0010 to 0021 of JP 2006-111718 A, the polyester resins described in JP 2017-105873 A, and the polyester resins described in WO 2013 / 168804 A, the contents of which are incorporated herein by reference.

[0019] The polyester resin layer of this embodiment may contain other components within the scope of this embodiment. Specifically, various additives such as antioxidants, light stabilizers, UV absorbers, plasticizers, extenders, matting agents, drying regulators, antistatic agents, antisettling agents, surfactants, flow improvers, drying oils, waxes, colorants, reinforcing agents, surface smoothing agents, leveling agents, curing reaction accelerators, and thickeners may also be added. For other components, see paragraph 0026 of JP 2006-111718 A, the contents of which are incorporated herein by reference.

[0020] <Layer containing polyamide resin (polyamide resin layer)> The multilayer body of this embodiment has a layer containing a polyamide resin (a polyamide resin layer), which functions as a barrier layer in the multilayer body. The polyamide resin layer in this embodiment is mainly composed of a xylylenediamine-based polyamide resin, which will be described later. Here, "main component" means that the xylylenediamine-based polyamide resin is the component with the largest content among the components contained in the polyamide resin layer, and preferably contains 80% by mass or more of the xylylenediamine-based polyamide resin, more preferably 90% by mass or more of the xylylenediamine-based polyamide resin, even more preferably 95% by mass or more of the xylylenediamine-based polyamide resin, and even more preferably 98% by mass or more of the xylylenediamine-based polyamide resin.

[0021] The polyamide resin contained in the polyamide resin layer contains structural units derived from diamines and structural units derived from dicarboxylic acids, and 70 mol % or more of the structural units derived from the diamines are derived from xylylenediamine, and 70 mol % or more of the structural units derived from the dicarboxylic acids are derived from a polyamide resin (hereinafter sometimes referred to as a "xylylenediamine-based polyamide resin") derived from an α,ω-straight-chain aliphatic dicarboxylic acid having 4 to 8 carbon atoms and an α,ω-straight-chain aliphatic dicarboxylic acid having 9 to 12 carbon atoms. Here, "70 mol % or more of the structural units derived from dicarboxylic acids are derived from α,ω-straight-chain aliphatic dicarboxylic acids having 4 to 8 carbon atoms and α,ω-straight-chain aliphatic dicarboxylic acids having 9 to 12 carbon atoms" means that the structural units derived from dicarboxylic acids include both structural units derived from α,ω-straight-chain aliphatic dicarboxylic acids having 4 to 8 carbon atoms and structural units derived from α,ω-straight-chain aliphatic dicarboxylic acids having 9 to 12 carbon atoms, and the total amount of structural units derived from α,ω-straight-chain aliphatic dicarboxylic acids having 4 to 8 carbon atoms and structural units derived from α,ω-straight-chain aliphatic dicarboxylic acids having 9 to 12 carbon atoms accounts for 70 mol % or more of all structural units derived from dicarboxylic acids.

[0022] The xylylenediamine-based polyamide resin in this embodiment is a copolymer in which the dicarboxylic acid-derived structural units include both structural units derived from an α,ω-straight-chain aliphatic dicarboxylic acid having 4 to 8 carbon atoms and structural units derived from an α,ω-straight-chain aliphatic dicarboxylic acid having 9 to 12 carbon atoms. That is, it is a copolymer of at least xylylenediamine, an α,ω-straight-chain aliphatic dicarboxylic acid having 4 to 8 carbon atoms, and an α,ω-straight-chain aliphatic dicarboxylic acid having 9 to 12 carbon atoms. By using such a copolymer, interlayer delamination resistance is improved. Specifically, when a blend of a polyamide resin (e.g., MXD6) in which 70 mol % or more of the diamine-derived structural units are derived from xylylenediamine and 70 mol % or more of the dicarboxylic acid-derived structural units are derived from an α,ω-linear aliphatic dicarboxylic acid having 4 to 8 carbon atoms is used with a polyamide resin (e.g., MXD10) in which 70 mol % or more of the diamine-derived structural units are derived from xylylenediamine and 70 mol % or more of the dicarboxylic acid-derived structural units are derived from an α,ω-linear aliphatic dicarboxylic acid having 9 to 12 carbon atoms, is used, sufficient peel resistance cannot be obtained. This is presumably because MXD6 and MXD10 are not sufficiently compatible with each other. In the present embodiment, this problem is solved by using a copolymer of these (e.g., MXD610). The xylylenediamine-based polyamide resin used in this embodiment is a copolymer of xylylenediamine (preferably meta-xylylenediamine), an α,ω-straight-chain aliphatic dicarboxylic acid having 4 to 8 carbon atoms (preferably adipic acid), and an α,ω-straight-chain aliphatic dicarboxylic acid having 9 to 12 carbon atoms (preferably sebacic acid), and of all structural units excluding terminal groups, preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, still more preferably 95% by mass or more, even more preferably 98% by mass or more, and still more preferably 99% by mass or more are composed of structural units derived from xylylenediamine, the α,ω-straight-chain aliphatic dicarboxylic acid having 4 to 8 carbon atoms, and the α,ω-straight-chain aliphatic dicarboxylic acid having 9 to 12 carbon atoms.

[0023] In the xylylenediamine-based polyamide resin, 70 mol% or more, preferably 80 mol% or more, more preferably 90 mol% or more, even more preferably 95 mol% or more, and even more preferably 99 mol% or more of the diamine-derived structural units are derived from xylylenediamine (preferably meta-xylylenediamine). The upper limit may be 100 mol%. Preferred xylylenediamines are meta-xylylenediamine and para-xylylenediamine, and meta-xylylenediamine is more preferred. In this embodiment, meta-xylylenediamine and para-xylylenediamine preferably account for 99 to 100 mol% of the total xylylenediamine. The molar ratio of meta-xylylenediamine to para-xylylenediamine in the xylylenediamine, when the total of meta-xylylenediamine and para-xylylenediamine is 100 mol, is preferably 10 to 100 / 90 to 0, more preferably 30 to 100 / 70 to 0, even more preferably 50 to 100 / 50 to 0, still more preferably 80 to 100 / 20 to 0, even more preferably 90 to 100 / 10 to 0, and still more preferably 95 to 100 / 5 to 0. By increasing the ratio of meta-xylylenediamine, it is possible to suppress an increase in melting point and lower the processing temperature, thereby more effectively suppressing the generation of scorch and gel due to the xylylenediamine-based polyamide resin.

[0024] Diamines other than xylylenediamine that can be used as the raw material diamine component of the polyamide resin in this embodiment include aliphatic diamines such as tetramethylenediamine, pentamethylenediamine, 2-methylpentanediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, dodecamethylenediamine, 2,2,4-trimethyl-hexamethylenediamine, and 2,4,4-trimethylhexamethylenediamine; 1,3-bis(aminomethyl)cyclohexyl methyl ester; Examples of the diamines include alicyclic diamines such as cyclohexane, 1,4-bis(aminomethyl)cyclohexane, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, bis(4-aminocyclohexyl)methane, 2,2-bis(4-aminocyclohexyl)propane, bis(aminomethyl)decalin, and bis(aminomethyl)tricyclodecane; and diamines having an aromatic ring such as bis(4-aminophenyl)ether, paraphenylenediamine, and bis(aminomethyl)naphthalene. These diamines may be used alone or in combination of two or more.

[0025] In the xylylenediamine-based polyamide resin of this embodiment, the dicarboxylic acid-derived structural units account for 70 mol% or more, preferably 75 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, still more preferably 95 mol% or more, even more preferably 98 mol% or more, and still more preferably 99.9 mol% or more of the dicarboxylic acid-derived structural units, which are structural units derived from an α,ω-linear aliphatic dicarboxylic acid having 4 to 8 carbon atoms and structural units derived from an α,ω-linear aliphatic dicarboxylic acid having 9 to 12 carbon atoms. The upper limit of this total may be 100 mol%. By using an α,ω-linear aliphatic dicarboxylic acid having 4 to 8 carbon atoms, the amide bond density can be increased, and a polyamide resin having excellent oxygen barrier properties tends to be obtained. Furthermore, by using an α,ω-linear aliphatic dicarboxylic acid having 9 to 12 carbon atoms, transparency tends to be improved compared to when only an α,ω-linear aliphatic dicarboxylic acid having 4 to 8 carbon atoms is used as the dicarboxylic acid component. In this embodiment, the ratio of the α,ω-straight chain aliphatic dicarboxylic acid having 4 to 8 carbon atoms and the α,ω-straight chain aliphatic dicarboxylic acid having 9 to 12 carbon atoms can be adjusted depending on the application.

[0026] More specifically, the proportion of the α,ω-linear aliphatic dicarboxylic acid having 4 to 8 carbon atoms (preferably adipic acid) in the dicarboxylic acid-derived structural units may be 10.0 mol% or more, 30.0 mol% or more, 50.0 mol% or more, 60.0 mol% or more, 65.0 mol% or more, or 70.0 mol%, preferably 71.0 mol% or more, more preferably 75.0 mol% or more, and even more preferably 78.0 mol% or more. By ensuring that the proportion is equal to or greater than the lower limit, gas barrier properties tend to be further improved. Furthermore, the proportion of the α,ω-linear aliphatic dicarboxylic acid having 4 to 8 carbon atoms is preferably 95.0 mol% or less, more preferably 90.0 mol% or less, even more preferably 85.0 mol% or less, even more preferably 84.0 mol% or less, and even more preferably 82.0 mol% or less. By ensuring that the proportion is equal to or less than the upper limit, transparency and delamination resistance tend to be significantly improved.

[0027] The proportion of the α,ω-linear aliphatic dicarboxylic acid having 9 to 12 carbon atoms (preferably sebacic acid) in the dicarboxylic acid-derived structural units may be 90.0 mol% or less, 70.0 mol% or less, 50.0 mol% or less, 40.0 mol% or less, 35.0 mol% or less, or 30.0 mol% or less, preferably 29.0 mol% or less, more preferably 25.0 mol% or less, and even more preferably 22.0 mol% or less. By setting the proportion below the upper limit, gas barrier properties tend to be further improved. Furthermore, the proportion of the α,ω-linear aliphatic dicarboxylic acid having 9 to 12 carbon atoms is preferably 5.0 mol% or more, more preferably 10.0 mol% or more, even more preferably 15.0 mol% or more, even more preferably 16.0 mol% or more, and even more preferably 18.0 mol% or more. In particular, by setting the proportion of structural units derived from an α,ω-linear aliphatic dicarboxylic acid having 9 to 12 carbon atoms to preferably 10.0 to 40.0 mol %, more preferably 15.0 to 35.0 mol %, and even more preferably 15.0 to 29.0 mol % of all structural units derived from dicarboxylic acids, transparency can be significantly improved.

[0028] Examples of the α,ω-straight-chain aliphatic dicarboxylic acid having 4 to 8 carbon atoms include succinic acid, glutaric acid, pimelic acid, adipic acid, and suberic acid, with adipic acid being preferred. Examples of α,ω-linear aliphatic dicarboxylic acids having 9 to 12 carbon atoms include azelaic acid, sebacic acid, undecanedioic acid, and dodecanedioic acid, with sebacic acid being preferred. Sebacic acid can be derived from plant materials, which can increase the bio-based content of the resin. In this embodiment, it is preferred that the α,ω-straight-chain aliphatic dicarboxylic acid having 4 to 8 carbon atoms comprises adipic acid, and the α,ω-straight-chain aliphatic dicarboxylic acid having 9 to 12 carbon atoms comprises sebacic acid. Furthermore, it is preferred that preferably 90 mol % or more, more preferably 95 mol % or more, and even more preferably 99 mol % or more of the α,ω-straight-chain aliphatic dicarboxylic acids having 4 to 8 carbon atoms are adipic acid, and preferably 90 mol % or more, more preferably 95 mol % or more, and even more preferably 99 mol % or more of the α,ω-straight-chain aliphatic dicarboxylic acids having 9 to 12 carbon atoms are sebacic acid.

[0029] In the xylylenediamine-based polyamide resin, the structural units derived from an α,ω-straight-chain aliphatic dicarboxylic acid having 4 to 8 carbon atoms and the structural units derived from an α,ω-straight-chain aliphatic dicarboxylic acid having 9 to 12 carbon atoms may each be used alone or in combination of two or more. When two or more types are contained, it is preferable that the total amount is in the above range.

[0030] Examples of dicarboxylic acid components other than the above-mentioned α,ω-linear aliphatic dicarboxylic acids having 4 to 12 carbon atoms include phthalic acid compounds such as isophthalic acid, terephthalic acid, and orthophthalic acid, and naphthalenedicarboxylic acids such as 1,2-naphthalenedicarboxylic acid, 1,3-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 1,6-naphthalenedicarboxylic acid, 1,7-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 2,7-naphthalenedicarboxylic acid, and these can be used alone or in combination of two or more.

[0031] A particularly preferred form of the xylylenediamine-based polyamide resin in this embodiment is a polyamide resin that contains structural units derived from diamines and structural units derived from dicarboxylic acids, in which 95 mol % or more (more preferably 98 mol % or more, and even more preferably 99.9 mol % or more) of the structural units derived from diamines are derived from meta-xylylenediamine, 75.0 to 95.0 mol % of the structural units derived from dicarboxylic acids are derived from adipic acid and 25.0 to 5.0 mol % are derived from sebacic acid, and the total of the structural units derived from adipic acid and the structural units derived from sebacic acid is 95 mol % or more (more preferably 98 mol % or more, and even more preferably 99.9 mol % or more) of the structural units derived from dicarboxylic acids.

[0032] The xylylenediamine-based polyamide resin used in this embodiment contains structural units derived from dicarboxylic acids and structural units derived from diamines, but may also contain structural units other than those derived from dicarboxylic acids and diamines, as well as other moieties such as terminal groups. Examples of other structural units include, but are not limited to, structural units derived from lactams such as ε-caprolactam, valerolactam, laurolactam, and undecalactam, and aminocarboxylic acids such as 11-aminoundecanoic acid and 12-aminododecanoic acid. Furthermore, the xylylenediamine-based polyamide resin used in this embodiment may contain trace components such as additives used in the synthesis. In the xylylenediamine-based polyamide resin of this embodiment, preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, still more preferably 95% by mass or more, even more preferably 98% by mass or more, and still more preferably 99% by mass or more of all structural units excluding terminal groups are composed of structural units derived from dicarboxylic acids and structural units derived from diamines, with the upper limit being 100% by mass.

[0033] The melting point of the xylylenediamine-based polyamide resin used in this embodiment, measured by differential scanning calorimetry, is preferably 195° C. or higher, more preferably 200° C. or higher, even more preferably 205° C. or higher, even more preferably 210° C. or higher, and even more preferably 215° C. or higher. The melting point of the xylylenediamine-based polyamide resin is preferably 235° C. or lower, more preferably 230° C. or lower, even more preferably 225° C. or lower, and even more preferably 220° C. or lower. The melting point is measured as described in the Examples below. When the polyamide resin layer in this embodiment contains two or more xylylenediamine-based polyamide resins, it is sufficient that the melting point of the xylylenediamine-based polyamide resin that is the main component satisfies the above range, and it is more preferable that the melting points of all the xylylenediamine-based polyamide resins satisfy the above range.

[0034] In this embodiment, the difference between the melting point of the polyester resin contained in the polyester resin layer and the melting point of the xylylenediamine-based polyamide resin contained in the polyamide resin layer (Tm of polyester resin - Tm of polyamide resin) is preferably 12°C or more. Furthermore, Tm of the polyester resin - Tm of the polyamide resin is preferably 57°C or less, more preferably 52°C or less, even more preferably 47°C or less, even more preferably 42°C or less, and even more preferably 37°C or less. By keeping the Tm at or below the upper limit, excellent moldability tends to be achieved in a multilayer configuration with the polyester resin.

[0035] The glass transition temperature of the xylylenediamine-based polyamide resin used in this embodiment, measured by differential scanning calorimetry, is preferably 61°C or higher, more preferably 70°C or higher, even more preferably 76°C or higher, even more preferably 78°C or higher, and even more preferably 80°C or higher. By setting the glass transition temperature at or above the lower limit, delamination tends to be suppressed during biaxial stretch blow molding within the temperature range used for blow molding. The glass transition temperature of the xylylenediamine-based polyamide resin is preferably 87°C or lower, more preferably 86°C or lower, even more preferably 85°C or lower, even more preferably 84°C or lower, and even more preferably 83°C or lower. By setting the glass transition temperature at or below the upper limit, excellent moldability tends to be achieved in a multilayer configuration with a polyester resin. The glass transition temperature is measured as described in the Examples section below. When the polyamide resin layer in this embodiment contains two or more xylylenediamine-based polyamide resins, it is sufficient that the glass transition temperature of the xylylenediamine-based polyamide resin that is the main component satisfies the above range, and it is more preferable that the glass transition temperatures of all the xylylenediamine-based polyamide resins satisfy the above range.

[0036] In this embodiment, the polyamide resin layer may contain a polyamide resin other than a xylylenediamine-based polyamide resin or a component other than a polyamide resin. Specific examples of the component other than a polyamide resin include a thermoplastic resin other than a polyamide resin, an oxidation promoter, a yellowing inhibitor, an oxygen absorber, a heat stabilizer, a light stabilizer, a moisture-proofing agent, a waterproofing agent, a lubricant (such as calcium stearate), and a spreading agent. For details about oxidation promoters and yellowing inhibitors, please refer to paragraphs 0061 to 0070 of WO 2021 / 177126, the contents of which are incorporated herein by reference.

[0037] The polyamide resin other than the xylylenediamine-based polyamide resin may be an aliphatic polyamide resin, a semi-aromatic polyamide resin, or a mixture of an aliphatic polyamide resin and a semi-aromatic polyamide resin, but preferably contains at least a semi-aromatic polyamide resin. For example, the polyamide resin may be as described in paragraphs 0011 to 0013 of JP 2011-132550 A, the contents of which are incorporated herein by reference. Examples of aliphatic polyamide resins include polyamide 6 and polyamide 66, with polyamide 66 being preferred. Examples of semi-aromatic polyamide resins include terephthalic acid-based polyamide resins (polyamide 6T, polyamide 9T, polyamide 10T), and terephthalic acid and isophthalic acid-based polyamide resins (polyamide 6T / 6I, polyamide 9T / 9I, polyamide 10T / 10I). The polyamide resin layer may contain only one kind of polyamide resin other than the xylylenediamine-based polyamide resin, or may contain two or more kinds of polyamide resins other than the xylylenediamine-based polyamide resin. The polyamide resin other than the xylylenediamine-based polyamide resin is preferably blended in an amount of 10 parts by mass or less per 100 parts by mass of the xylylenediamine-based polyamide resin.

[0038] <Characteristics of multilayer bodies> The multilayer body of this embodiment can have low haze. Specifically, the haze of the multilayer body is preferably 1.30% or less, more preferably 1.20% or less, even more preferably 1.10% or less, even more preferably 1.00% or less, and even more preferably 0.72% or less. The ideal lower limit is 0%, but even if it is 0.01% or more, the required performance is met. Such low haze is particularly achieved by using an isophthalic acid-modified polyester resin and a polyamide resin obtained by combining, as raw material monomers, an α,ω-linear aliphatic dicarboxylic acid having 4 to 8 carbon atoms and an α,ω-linear aliphatic dicarboxylic acid having 9 to 12 carbon atoms. The haze is measured as described in the Examples section below.

[0039] <Layer configuration> The multilayer body of this embodiment is a multilayer body having at least one layer containing a polyester resin as a main component (polyester resin layer) and at least one layer containing a polyamide resin as a main component (polyamide resin layer). The polyester resin layer and the polyamide resin layer are usually in contact with each other. The number of layers constituting the multilayer body is preferably at least three. In this embodiment, an example is one including at least two polyester resin layers and at least one polyamide resin layer. That is, a preferred embodiment of the multilayer body of this embodiment is a multilayer body in which a layer containing a polyester resin, a layer containing a polyamide resin, and a layer containing a polyester resin are arranged in this order (polyester resin layer / polyamide resin layer / polyester resin layer). More specifically, the number of layers constituting the multilayer body is more preferably 3 to 10 layers, and even more preferably 3 to 5 layers. The number of polyester resin layers in the multilayer container is preferably 1 to 5, more preferably 2 to 4. The number of polyamide resin layers in the multilayer container is preferably 1 to 3, more preferably 1 or 2. The multilayer container may also have a polyester resin layer / polyamide resin layer configuration (where the polyester resin layer is the inner layer) or a polyamide resin layer / polyester resin layer configuration (where the polyamide resin layer is the inner layer) consisting of one polyester resin layer and one polyamide resin layer, or a five-layer configuration of polyester resin layer / polyamide resin layer / polyester resin layer / polyamide resin layer / polyamide resin layer / polyester resin layer.

[0040] From the viewpoint of better interlayer delamination resistance, the polyamide resin layer is preferably disposed centrally or internally, and internal disposition is more preferred. "Polyamide resin layer is disposed centrally" means that the polyamide resin layer is located near the center in the thickness direction in a cross section of the multilayer body in the thickness direction. "Polyamide resin layer is disposed internally" means that the polyamide resin layer is located near the inner surface in the thickness direction in a cross section of the multilayer body in the thickness direction. An example of the position of the polyamide resin layer in this embodiment is an embodiment in which the intermediate layer in JP-A-02-229023 is a polyamide resin layer, the contents of which are incorporated herein by reference.

[0041] The multilayer body of this embodiment may include, in addition to the polyester resin layer and the polyamide resin layer, any layer depending on the desired performance, etc. Examples of the optional layer include an oxygen absorbing layer, an adhesive layer, a gas barrier layer other than the polyamide resin layer, a protective layer, a design layer, etc. For details of these, please refer to the descriptions in paragraphs 0012 to 0046 of JP 2021-080025 A, the contents of which are incorporated herein by reference.

[0042] <Stretching> The multilayer body of this embodiment is preferably stretched, for example, by biaxial stretch blow molding, which is carried out when forming multilayer containers such as bottles. In a preferred embodiment of the stretching of this embodiment, a preform (sometimes called a parison) containing the multilayer body of this embodiment is preferably biaxially stretched and blow-molded. In particular, a stretching step using a stretch rod and high-pressure air is preferably included. Details of biaxially stretched and blow-molded are described below.

[0043] The thickness of the polyester resin and the thickness of the polyamide resin layer in the stretched multilayer body are the same as the thickness of the polyester resin and the thickness of the polyamide resin layer in the multilayer container described below, respectively, and the preferred ranges are also the same. In the multilayer body of this embodiment, the mass of the polyamide resin layer is preferably 1% by mass or more, more preferably 2% by mass or more, and may be 3% by mass or more, relative to the total mass of the multilayer body, and is preferably 20% by mass or less, more preferably 15% by mass or less, and particularly preferably 10% by mass or less. By making the mass equal to or greater than the lower limit, the barrier properties of the multilayer body tend to be improved. Furthermore, by making the mass equal to or less than the upper limit, the transparency of the multilayer body tends to be further improved. Meanwhile, in the multilayer body of this embodiment, the mass of the polyester resin layer is preferably 80% by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass or more, relative to the total mass of the multilayer body. Furthermore, in the multilayer body of this embodiment, the mass of the polyester resin layer is preferably 99% by mass or less, more preferably 98% by mass or less, and may be 97% by mass or less, relative to the total mass of the multilayer body.

[0044] <Multilayer container> In this embodiment, a multilayer container including the multilayer body of this embodiment is exemplified. The shape of the multilayer container is not particularly limited, and may be, for example, a molded container such as a bottle, a cup, a tube, a tray, or Tupperware, or a bag-like container such as a pouch, a standing pouch, or a zippered storage bag. In this embodiment, a bottle is preferred. Furthermore, it is not necessary for the multilayer body of this embodiment, particularly the polyamide resin layer, to be contained in all parts of the bottle. For example, a polyamide resin layer may be contained in the body of the bottle, but not in the vicinity of the opening (seal). However, it is preferable for the polyamide resin layer to extend to the vicinity of the opening of the bottle, as this will further enhance the barrier performance.

[0045] The capacity of the multilayer container of this embodiment is preferably 0.1 to 2.0 L, more preferably 0.2 to 1.5 L, and even more preferably 0.3 to 1.0 L, in view of the preservation of the contents. The thickness of the body (total of polyester resin layer, polyamide resin layer, etc.) of the multilayer container of this embodiment is preferably 0.02 mm or more, more preferably 0.15 mm or more, even more preferably 0.20 mm or more, and is preferably 5.0 mm or less, more preferably 3.0 mm or less, even more preferably 2.5 mm or less. In the multilayer container of this embodiment, the thickness of the inner layer (polyester resin layer) is preferably 0.01 mm or more, more preferably 0.03 mm or more, and even more preferably 0.05 mm or more, and is preferably 2.0 mm or less, more preferably 1.5 mm or less, and even more preferably 1.0 mm or less. The thickness of the outer layer (polyester resin layer) is preferably 0.01 mm or more, more preferably 0.05 mm or more, and even more preferably 0.05 mm or more, and is preferably 2.0 mm or less, more preferably 1.5 mm or less, and even more preferably 1.0 mm or less. The thickness of the polyamide resin layer is preferably 0.005 mm or more, more preferably 0.01 mm or more, even more preferably 0.02 mm or more, and preferably 0.2 mm or less, more preferably 0.15 mm or less, and even more preferably 0.1 mm or less. When two or more polyamide resin layers are present, the total thickness of the polyamide resin layers preferably has the above thickness. When two or more polyamide resin layers are present and an intermediate layer is present between the polyamide resin layers, the thickness of the intermediate layer is preferably 0.01 mm or more, more preferably 0.03 mm or more, and even more preferably 0.05 mm or more, and preferably 2.0 mm or less, more preferably 1.5 mm or less, and even more preferably 1.0 mm or less.

[0046] In the multilayer container (particularly, a bottle) of this embodiment, the mass of the polyamide resin layer is preferably 1% by mass or more, more preferably 2% by mass or more, and may be 3% by mass or more, relative to the total mass of the multilayer container. It is also preferably 20% by mass or less, more preferably 15% by mass or less, and particularly preferably 10% by mass or less. By setting the mass at or above the lower limit, the barrier properties of the multilayer container tend to be improved. Furthermore, by setting the mass at or below the upper limit, the transparency of the multilayer container tends to be further improved. Meanwhile, in the multilayer container of this embodiment, the mass of the polyester resin layer is preferably 80% by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass or more, relative to the total mass of the multilayer container. Furthermore, in the multilayer container of this embodiment, the mass of the polyester resin layer is preferably 99% by mass or less, more preferably 98% by mass or less, and may be 97% by mass or less, relative to the total mass of the multilayer container.

[0047] The multilayer container of this embodiment has excellent oxygen barrier properties. Specifically, the oxygen barrier property of the multilayer container of this embodiment is preferably 0.026 cc / (bottle·day·0.21 atm) or less, more preferably 0.025 cc / (bottle·day·0.21 atm) or less, even more preferably 0.024 cc / (bottle·day·0.21 atm) or less, even more preferably 0.023 cc / (bottle·day·0.21 atm) or less, and even more preferably 0.022 cc / (bottle·day·0.21 atm) or less. The ideal lower limit is 0 cc / (bottle·day·0.21 atm), but even a value of 0.001 cc / (bottle·day·0.21 atm) or more will fully satisfy the required performance. Such oxygen barrier properties are achieved particularly by using a polyamide resin using an α,ω-linear aliphatic dicarboxylic acid having 4 to 8 carbon atoms as a raw material monomer, and by increasing the thickness of the polyamide resin layer.

[0048] The multilayer container of this embodiment has excellent carbon dioxide gas barrier properties. Specifically, the carbon dioxide barrier properties of the multilayer container of this embodiment are preferably 3.51 cc / (bottle·day) or less, and more preferably 3.50 cc / (bottle·day) or less. The ideal lower limit is 0 cc / (bottle·day), but even if it is 1.00 cc / (bottle·day) or more, the required performance is fully satisfied. Such carbon dioxide barrier properties are achieved, in particular, by using a polyamide resin using an α,ω-linear aliphatic dicarboxylic acid having 4 to 8 carbon atoms as a raw material monomer, by increasing the thickness of the polyamide resin layer, etc.

[0049] The items that can be stored in the multilayer container of this embodiment are not particularly limited, and examples include food, cosmetics, pharmaceuticals, toiletries, mechanical, electrical, and electronic parts, oils, resins, etc., but it is particularly suitable for use as a container for storing food. Examples of the storage container include processed seafood products, processed livestock products, rice dishes, and liquid foods. It is particularly suitable for preserving foods that are susceptible to oxygen. For details, please refer to paragraphs 0032 to 0035 of JP 2011-37199 A, the contents of which are incorporated herein by reference. The food to be filled is not particularly limited, but specific examples include beverages such as vegetable juice, fruit juice, tea, coffee and coffee drinks, milk and dairy drinks, mineral water, ionic drinks, alcoholic beverages, lactic acid bacteria drinks, and soy milk; gel foods such as tofu, egg tofu, jellies, puddings, mizu yokan, mousse, yogurt, and almond tofu; condiments such as sauces, soy sauce, ketchup, noodle soup, dipping sauce, vinegar, mirin, dressings, jam, mayonnaise, miso, pickle bases, and grated spices; salami, ham, sausage, yakitori, Processed meat products such as meatballs, hamburgers, roast pork, beef jerky, etc.; processed seafood products such as kamaboko, boiled shellfish, boiled fish, chikuwa, etc.; processed rice products such as porridge, cooked rice, mixed rice, red rice, etc.; sauces such as meat sauce, mapo sauce, pasta sauce, curry, stew, hayashi sauce, etc.; processed dairy products such as cheese, butter, cream, condensed milk, etc.; processed egg products such as boiled eggs, soft-boiled eggs, etc.; boiled vegetables and boiled beans; prepared dishes such as fried, steamed, stir-fried, simmered, and grilled foods; pickles; noodles and pasta such as udon, soba, and spaghetti; and fruits in syrup, etc. Depending on the object to be preserved, the multilayer container may be sterilized or disinfected using ultraviolet rays, electron beams, gamma rays, X-rays, or the like.

[0050] <Method of manufacturing a multilayer body> The method for producing the multilayer body of this embodiment is not particularly limited, and any known method for producing a multilayer body can be used. In producing a multilayer body, it is preferable to prepare a polyester resin composition constituting the polyester resin layer and a polyamide resin composition constituting the polyamide resin layer (hereinafter collectively referred to as "resin composition"). The polyamide resin composition uses at least a xylylenediamine-based polyamide resin, but when other polyamide resins are contained, there are no particular limitations on the blending method. They may be dry-blended and supplied when producing a bottle preform, or they may be melt-blended using a single-screw extruder or twin-screw extruder prior to producing the preform, or some of the resins may be melt-blended to prepare a masterbatch and used. Furthermore, when a resin additive such as an oxidation reaction accelerator is blended into the polyamide resin layer, the additive may be dry-blended with the xylylenediamine-based polyamide resin, or may be blended after being made into a masterbatch using a polyamide resin or the like, or may be melt-blended. The same applies when the polyester resin composition contains two or more types of polyester resins or when it contains resin additives or the like.

[0051] As a method for producing the multilayer body, an appropriate method is selected taking into consideration the structure of the molded product containing the multilayer body. For example, a film or sheet can be formed by extruding a molten resin composition from an extruder through a T-die, a circular die, etc. The obtained film can also be processed into a stretched film by stretching it. Bottle-shaped packaging containers can be obtained by injecting a molten resin composition into a mold from an injection molding machine to produce a preform, followed by blow stretching (injection blow molding, injection stretch blow molding), or by extruding a molten resin composition from an extrusion molding machine into a mold to produce a parison, which is then blown into the mold (direct blow molding). Containers such as trays and cups can be produced by injecting a molten resin composition into a mold from an injection molding machine, or by molding a sheet using a molding method such as vacuum molding or pressure molding.

[0052] The multilayer container of this embodiment is preferably produced by biaxially stretching blow molding a preform. The multilayer container of this embodiment may be produced by cold parison molding or hot parison molding. Cold parison (two-stage molding) is a molding method in which the preform after injection molding is cooled to room temperature, stored, and then reheated in a separate device before being supplied to blow molding. Hot parison molding (single-stage molding) is a blow molding method in which the parison is preheated during injection molding and temperature controlled before blowing without being completely cooled to room temperature. In hot parison molding, the injection molding machine, temperature control zone, and blow molding machine are often installed in the same molding unit, and preform injection molding and blow molding are carried out.

[0053] A first embodiment of the method for manufacturing a multilayer container of this embodiment is a form in which molding is performed by cold parison molding. Hereinafter, a description will be given with reference to Fig. 1. However, it goes without saying that the first embodiment is not limited to the configuration shown in Fig. 1. In Fig. 1, first, a preform 1 is heated (Fig. 1(1)). Heating is performed by an infrared heater 2 or the like.

[0054] The heated preform is then biaxially stretched and blow-molded. Specifically, it is placed in a mold 3 (see (2) in Figure 1) and blow-molded while being stretched by a stretch rod 4 (see (3) and (4) in Figure 1). For example, the preform may be stretched axially by mechanical means, such as by heating the surface of the preform and then pressing it with a core rod insert. Then, high-pressure air, typically at 2 to 4 MPa, is blown into the preform to stretch it laterally. To improve the heat resistance of the container, a blow-molding method that increases crystallinity or reduces residual strain may be combined. For example, a method (single blow molding) in which the surface of a multilayer preform is heated and then blow-molded in a mold at a temperature above the glass transition point may be used. Furthermore, so-called double blow molding may be used, consisting of a primary blow-molding step in which the preform is biaxially stretched and blow-molded to a size larger than the final shape, a step in which this primary blow-molded product is heated and thermally shrunk to form a secondary intermediate molded product, and finally, a secondary blow-molding step in which this secondary intermediate molded product is blow-molded into the final container shape. After the blow molding, the mold 3 is removed, and a multilayer container 5 is obtained ((5) in FIG. 1).

[0055] A second embodiment of the method for producing a multilayer container of this embodiment is a form in which molding is performed by hot parison molding. Hot parison molding is a blow molding method in which the parison is preheated during injection molding and temperature controlled before blowing in one stage without being completely cooled to room temperature, and molding is performed without going through the step of Figure 1(1) above.

[0056] In cold parison molding and hot parison molding, the parison temperature before blow molding is determined taking into consideration the glass transition temperature (Tg) of the polyester resin constituting the polyester resin layer and the polyamide resin constituting the polyamide resin layer. "Before blow molding" refers to, for example, the time immediately before blowing after passing through the preheating zone. The parison temperature is determined based on the glass transition temperature (Tg) of the resin with the highest glass transition temperature among the polyester resin and polyamide resin constituting the multilayer body of this embodiment. max ) is preferred, and Tg max The temperature range is more preferably +0.1°C to 50°C. In addition, the glass transition temperature (Tg min ) and the Tg max The difference is preferably 40° C. or less, and more preferably 30° C. or less. By setting the difference within this range, the blow moldability tends to be further improved. Furthermore, when at least one of the polyester resin and the polyamide resin is a crystalline resin, the lowest crystallization temperature (Tc) of the crystalline resin is min ) and the highest temperature (Tg max ) is preferably larger. min -Tg max is preferably 5°C or higher, more preferably 10°C or higher. min -Tg max The upper limit of the temperature is practically 100° C. By setting the temperature in this range, the blow moldability tends to be further improved.

[0057] In addition, the method for manufacturing the multilayer container of the present embodiment can take into consideration the descriptions in paragraphs 0070 to 0074 of JP-A-2016-198912, paragraphs 0085 to 0119 of JP-A-2016-169027, and the description of JP-A-60-232952 without departing from the gist of the present embodiment, and these contents are incorporated herein.

Examples

[0058] The present invention will be described more specifically with reference to the following examples. The materials, amounts used, ratios, treatment details, treatment procedures, etc. shown in the following examples can be appropriately changed without departing from the gist of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below. When it is difficult to obtain the measuring instruments, etc. used in the examples due to their being obsolete, etc., measurement can be performed using other devices having equivalent performance.

[0059] 1. Raw materials <Polyester resin> PET: Isophthalic acid-modified polyethylene terephthalate resin (intrinsic viscosity: 0.83 dL / g), trade name: BK2180, manufactured by Mitsubishi Chemical Corporation (melting point 248°C), isophthalic acid content based on all carboxylic acid components: 1.4 mol%, glass transition temperature: 79°C

[0060] <Polyamide resin (PA)> MXD610(80 / 20): Polyamide resin obtained in the following synthesis example <<Synthesis example of MXD610(80 / 20)>> In a reaction vessel equipped with a stirrer, a partial condenser, a total condenser, a thermometer, a dropping funnel, a nitrogen inlet tube, and a strand die, 10,000 g (68 mol) of adipic acid, 3,460 g (17.1 mol) of sebacic acid, 0.38 g of sodium hypophosphite monohydrate (NaH2PO2·H2O) (5 ppm in terms of the phosphorus atom concentration in the polyamide resin), and 0.15 g of sodium acetate were accurately weighed, and after sufficient nitrogen substitution, nitrogen was filled to an internal pressure of 0.4 MPa, and then the system was heated to 190°C while stirring under a small amount of nitrogen flow. 11,813 g (87 mol) of metaxylylenediamine was added dropwise thereto with stirring, and the temperature inside the system was continuously increased while removing the generated condensation water out of the system. After completion of the dropwise addition of metaxylylenediamine, the internal temperature was raised. When it reached 255 °C, the inside of the reaction vessel was depressurized, and the internal temperature was further raised to continue the melt polycondensation reaction at 260 °C for 10 minutes. Thereafter, the system was pressurized with nitrogen, and the obtained polymer was taken out from the strand die and pelletized to obtain polyamide MXD610(80 / 20). The melting point of the obtained polyamide MXD610(80 / 20) was 212 °C, and the glass transition temperature was 82 °C.

[0061] MXD610(70 / 30) <<Synthesis Example of MXD610(70 / 30)>> In a reaction vessel equipped with a stirrer, a partial condenser, a total condenser, a thermometer, a dropping funnel, a nitrogen inlet tube, and a strand die, 10,000 g (68 mol) of adipic acid, 5,931 g (29.3 mol) of sebacic acid, 0.44 g of sodium hypophosphite monohydrate (NaH2PO2·H2O) (5 ppm in terms of the phosphorus atom concentration in the polyamide resin), and 0.17 g of sodium acetate were blended. After sufficient nitrogen substitution, nitrogen was filled to an internal pressure of 0.4 MPa, and the system was heated to 190 °C while stirring under a small amount of nitrogen stream. 13,500 g (99 mol) of metaxylylenediamine was added dropwise thereto with stirring, and the temperature inside the system was continuously increased while removing the generated condensation water out of the system. After completion of the dropwise addition of metaxylylenediamine, the internal temperature was raised. When it reached 255 °C, the inside of the reaction vessel was depressurized, and the internal temperature was further raised to continue the melt polycondensation reaction at 260 °C for 10 minutes. Thereafter, the system was pressurized with nitrogen, and the obtained polymer was taken out from the strand die and pelletized to obtain polyamide MXD610(70 / 30). The melting point of the obtained MXD610(70 / 30) was 210 °C, and the glass transition temperature was 75 °C.

[0062] MXD10 <<Synthesis Example of MXD10>> Sebacic acid (manufactured by CASDA) was placed in a jacketed reactor equipped with a stirrer, partial condenser, condenser, thermometer, dropping tank, and nitrogen gas inlet tube. The contents were thoroughly purged with nitrogen and heated to 170°C to melt. While stirring the contents, metaxylylenediamine (manufactured by Mitsubishi Gas Chemical Company, Inc., MXDA) was gradually added dropwise to a molar ratio of 1:1 to sebacic acid, while the temperature was raised to 240°C. After the addition was complete, the temperature was raised to 260°C and continued for 20 minutes. The pressure inside the reaction system was then continuously reduced to 0.08 MPa, and the reaction was continued. After the reaction was completed, the reactor was pressurized with 0.2 MPa of nitrogen gas, and the polymer was removed as a strand from a nozzle at the bottom of the polymerization vessel. After water cooling, it was pelletized using a pelletizer. The melting point of the resulting MXD10 was 190°C, and the glass transition temperature was 60°C.

[0063] MXD6: Polyamide resin synthesized from metaxylylenediamine and adipic acid, melting point: 237°C, glass transition temperature: 88°C, manufactured by Mitsubishi Gas Chemical Company, Inc., product number: S6007

[0064] <Measurement of melting point and glass transition temperature> The melting point (Tm, unit: ° C.) and glass transition temperature (Tg, unit: ° C.) of the resin were measured by differential scanning calorimetry (DSC) in accordance with JIS K7121 and K7122. The resin (pellets) was crushed and placed in the measurement pan of a differential scanning calorimeter, and after pretreatment in a nitrogen atmosphere, the temperature was raised to 300°C at a rate of 10°C / min and rapidly cooled, measurements were performed. The measurement conditions were a temperature rise rate of 10°C / min, held at 300°C for 5 minutes, and then a temperature drop rate of -5°C / min down to 100°C to determine the glass transition temperature (Tg) and melting point (Tm). The differential scanning calorimeter used was a "DSC-60" manufactured by SHIMADZU CORPORATION.

[0065] 2. Examples 1 to 3, Comparative Examples 1 to 3, Reference Example 1 <Preform manufacturing> A preform partially having a three-layer structure consisting of (Y) / (X) / (Y) was manufactured using an injection molding machine (Sumitomo Heavy Industries, Ltd., Model SE-DU130CI) with two injection cylinders and a two-cavity multilayer hot runner mold (Kortec) under the conditions shown below. Specifically, thermoplastic polyester resin (PET) for layer (Y) was first injected from the injection cylinder. While maintaining the injected state of layer (Y), polyamide resin (PA) (listed in Table 1) for layer (X) was injected from a separate injection cylinder together with the PET for layer (Y). Finally, the required amount of PET for layer (Y) was injected to fill the cavity, yielding a preform (25 g) partially having a three-layer structure consisting of (Y) / (X) / (Y). The amounts of layer (Y) and layer (X) injected, relative to the total amount of injected resin (100 mass%), are shown in Table 1. The preform had a total length of 92 mm, an outer diameter of 22 mm, and a wall thickness of 3.9 mm. The preform was packaged in a moisture-proof package immediately after production and stored in this state until just before the start of biaxial stretch blowing, which will be described later. <<Molding conditions>> Skin side (Y) injection cylinder temperature: 280℃ Core side (X) injection cylinder temperature: 260℃ Resin flow path temperature in the mold: 290℃ Mold cooling water temperature: 15℃ Cycle time: 33 seconds <Manufacturing of multi-layer containers> The preform was biaxially stretched and blow-molded using a biaxial stretch blow molding machine (Frontier, model EFB1000ET) to obtain a petaloid bottle (multilayer container). The bottle (multilayer container) had a total length of 223 mm, an outer diameter of 65 mm, and an internal volume of 500 mL (surface area: 0.04 m). 2 The thickness of each layer of the resulting multilayer container is shown in Table 1, and in Table 1, the thickness of each layer (from the outer layer) is shown as layer (Y) / layer (X) / layer (Y) (mm). Preform heating temperature: 105℃ Primary blow pressure: 0.9MPa Secondary blow pressure: 2.5MPa Primary blow delay time: 0.30sec Primary blow time: 0.30sec Secondary blow time: 2.0 seconds Blow exhaust time: 0.6 seconds Mold temperature: 15℃

[0066] <Haze (%) on the side of the multi-layer container> The side surface of the multilayer container was measured using a haze meter in accordance with JIS K 7136, and the average value of four measurements was calculated. The haze meter used was COH7700 (manufactured by Nippon Denshoku Industries, white LED light source).

[0067] <Oxygen barrier properties> The multilayer containers produced in the examples and comparative examples were filled with 100 mL of water, and nitrogen at 1 atm was circulated through the multilayer container at 20 mL / min under conditions of an oxygen partial pressure of 0.21 atm, an internal humidity of 100% RH (relative humidity), an external humidity of 50% RH, and a temperature of 23°C. After 200 hours, the amount of oxygen contained in the nitrogen that had circulated through the multilayer container was detected using a coulometric sensor to measure the oxygen permeability (unit: cc / (bottle day 0.21 atm)). The oxygen permeability measuring device used was a product name "OX-TRAN 2 / 61" manufactured by MOCON.

[0068] <Carbon dioxide gas barrier properties> The multilayer containers produced in the Examples and Comparative Examples were filled with 500 mL of 4.6 GV carbonated water, capped, and then stored for 7 days at 23°C and 50% relative humidity. The shelf life of the multilayer container was then measured using a carbon dioxide permeability measuring device at 23°C, with a relative humidity of 100% inside the container and a relative humidity of 50% outside the container, for a carbon dioxide loss rate of 20%. The carbon dioxide barrier property was measured in units of cc / (bottle·day). The longer the measured shelf life, the better the carbon dioxide barrier property. The carbon dioxide gas permeability measuring device used was "PERMATRAN-C Model 10" (registered trademark) manufactured by MOCON.

[0069] <Side impact test> The resulting multilayer container was subjected to a side impact test as follows. First, the multilayer container obtained above was filled with 500 mL of colored carbonated water (4.2 gas volumes), capped, and left to stand at 23°C for 7 days. A side impact test was then conducted by striking the side of the bottle (123 mm above the bottom) with a pendulum equipped with a striking load (1862 g). Since delamination areas became cloudy and could be visually identified, the presence or absence of delamination in the multilayer container was determined visually. Multilayer containers showing even partial delamination were considered to have delamination. Five multilayer containers were tested, and delamination was evaluated based on the average number of strikes required to cause delamination. A: 20 or more hits B: Number of hits: 10 or more but less than 20 C: Less than 10 hits

[0070] [Table 1]

[0071] In Comparative Example 3, "MXD6 / MXD10=80 / 20" indicates the blend ratio (mass ratio). As is clear from the above results, the multilayer body and multilayer container of the present invention were excellent in a balanced manner in oxygen barrier property, delamination resistance (evaluated in a side impact test), and transparency (evaluated in a haze test). In particular, by using a combination of an α,ω-linear aliphatic dicarboxylic acid having 4 to 8 carbon atoms and an α,ω-linear aliphatic dicarboxylic acid having 9 to 12 carbon atoms as dicarboxylic acid raw material monomers for the xylylenediamine-based polyamide resin, delamination resistance and transparency were surprisingly improved. This is evident from the fact that Example 1 had improved delamination resistance and transparency compared to Comparative Example 1 and Reference Example 1. Furthermore, the multilayer body and multilayer container of the present invention also had excellent carbonate barrier property. [Explanation of symbols]

[0072] 1 Preform 2 heaters 3. Mold 4 Extension Rod 5 Multilayer container

Claims

1. It has a layer containing a polyester resin and a layer containing a polyamide resin, The polyamide resin is a multilayer copolymer that includes constitutional units derived from diamines and constitutional units derived from dicarboxylic acids, in which 70 mol % or more of the constitutional units derived from diamines are derived from xylylenediamine, and 71.0 to 95.0 mol % of the constitutional units derived from dicarboxylic acids are derived from an α,ω-linear aliphatic dicarboxylic acid having 4 to 8 carbon atoms and 29.0 to 5.0 mol % are derived from an α,ω-linear aliphatic dicarboxylic acid having 9 to 12 carbon atoms.

2. The multilayer body according to claim 1, wherein 75.0 to 95.0 mol % of the structural units derived from dicarboxylic acids are derived from linear α,ω-aliphatic dicarboxylic acids having 4 to 8 carbon atoms, and 25.0 to 5.0 mol % are derived from linear α,ω-aliphatic dicarboxylic acids having 9 to 12 carbon atoms.

3. 3. The multilayer body according to claim 1, wherein the α,ω-linear aliphatic dicarboxylic acid having 4 to 8 carbon atoms comprises adipic acid, and the α,ω-linear aliphatic dicarboxylic acid having 9 to 12 carbon atoms comprises sebacic acid.

4. The multilayer body according to any one of claims 1 to 3, wherein 70 mol % or more of the constitutional units derived from the diamine are derived from metaxylylenediamine.

5. The multilayer body according to any one of claims 1 to 4, wherein the polyester resin comprises constitutional units derived from a diol and constitutional units derived from a dicarboxylic acid, and 70 mol % or more of the constitutional units derived from the diol are derived from ethylene glycol, 60 to 99 mol % of the constitutional units derived from the dicarboxylic acid are derived from at least one selected from terephthalic acid and esters thereof, and 40 to 1 mol % are derived from at least one selected from isophthalic acid and esters thereof.

6. The multilayer body according to any one of claims 1 to 5, which is stretched.

7. A multilayer container comprising the multilayer body according to any one of claims 1 to 6.

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