JP6519288B2 - Multilayer structure - Google Patents

Description

  The present invention relates to a multilayer structure, and more particularly, to a multilayer structure suitably used as a container for packaging an oxygen-dissident substance such as beverage, food, cosmetics and medicine, or a preform thereof.

  Various plastic containers are used as containers for packaging beverages, foods, cosmetics, medicines and the like. Plastic containers are superior in terms of light weight, high transparency, freedom of design, safety, etc. However, gases such as oxygen can pass through the wall of the container compared to metal cans and glass bottles Since it is easy to permeate | transmit, it becomes an important subject to prevent the deterioration of the content by the oxygen from the container exterior, and the fall of a taste or an aroma.

Conventionally, a method has been known in which oxygen is prevented from entering the inside of the container by forming a body of the plastic container in a multilayer structure and providing a barrier layer made of a metaxylylene group-containing polyamide between surface layers made of polyester such as polyethylene terephthalate. ing. However, this method is excellent in that high barrier property and transparency can be obtained, but it is easy to cause delamination due to falling or external impact, and the barrier property is deteriorated and the appearance is deteriorated due to it. It was a problem.
With respect to the above problems, a method has been proposed in which delamination is prevented by blending and using polyethylene terephthalate in addition to the metaxylylene group-containing polyamide in the barrier layer (Japanese Patent Application Laid-Open No. 2007-223667 (Patent Document 1) Patent No. 5387054 (patent document 2), JP-A-58-197050 (patent document 3), etc.). Although this method is excellent in that even if a small amount of polyethylene terephthalate is blended with the metaxylylene group-containing polyamide, the barrier property is not significantly impaired, delamination may not be sufficiently prevented if the external impact is large. There was a problem that handling was difficult.
For the purpose of improving the barrier property, or for the purpose of reducing aldehydes which are trace impurities contained in the polyester, a method of blending a metaxylylene group-containing polyamide with the surface layer has been proposed. It is not examined about preventing delamination (Unexamined-Japanese-Patent No. 2000-168017 (patent document 4), Unexamined-Japanese-Patent No. 2006-290436 (patent document 5)).

JP 2007-223667 A Patent No. 5 387 705 Japanese Patent Application Laid-Open No. 58-197050 Japanese Patent Laid-Open No. 2000-168017 Unexamined-Japanese-Patent No. 2006-290436

  Under such circumstances, there is a need to provide a multilayer structure that has at least in part a multilayer structure including an inner layer, an outer layer and a barrier layer, and that can prevent delamination at a higher level.

  As a result of intensive investigations in view of the above problems, the present inventors have found that, as a barrier layer, in addition to the metaxylylene group-containing polyamide and blending polyester at a predetermined ratio, it is used for the inner layer and outer layer which are surface layers. By blending and using a metaxylylene group-containing polyamide in a predetermined amount ratio in addition to polyester, interlayer adhesion is improved as compared with the case of using a blend of a metaxylylene group-containing polyamide and a polyester only in the barrier layer or only in the surface layer. The present invention has been found to be dramatically improved, and the present invention has been completed based on these findings.

That is, the present invention provides a multilayer structure shown below.
[1] A multilayer structure having, at least in part, a multilayer structure including an inner layer, an outer layer, and at least one barrier layer located between the inner layer and the outer layer,
94 to 99.9 mass% of a polyester (A) in which the inner layer and the outer layer each independently contain a dicarboxylic acid unit containing 80 mol% or more of terephthalic acid units and a diol unit containing 80 mol% or more of ethylene glycol units, A resin composition (C) containing 0.1 to 6% by mass of a polyamide (B) containing a diamine unit containing 70 mol% or more of a metaxylylene diamine unit and a dicarboxylic acid unit,
1 to 40% by mass of a polyester (A) in which the barrier layer contains a dicarboxylic acid unit containing 80 mol% or more of terephthalic acid units and a diol unit containing 80 mol% or more of ethylene glycol units, and 70 metaxylylene diamine units The multilayer structure which consists of a resin composition (D) containing 60-99 mass% of polyamide (B) containing the diamine unit and the dicarboxylic acid unit which contain mol% or more.
[2] The multilayer according to [1], wherein the polyamide (B) is a polyamide comprising a diamine unit containing 70 mol% or more of metaxylylene diamine unit and a dicarboxylic acid unit containing 70 mol% or more of adipic acid unit Structure.
[3] Polyamide (B) is a diamine unit containing 70 mol% or more of metaxylylene diamine unit, and a dicarboxylic acid unit containing 70 to 99 mol% of adipic acid unit and 1 to 30 mol% of isophthalic acid unit The multilayer structure according to [1] or [2], which is a polyamide comprising.
[4] A polyester (A) is a diol containing 80 to 99.9% by mole of a terephthalic acid unit and a dicarboxylic acid unit containing 0.1 to 10% by mole of a metal sulfoisophthalic acid unit and 80% by mole or more of an ethylene glycol unit The multilayer structure according to any one of [1] to [3], which is a polyester containing a unit.
[5] The multilayer structure according to any one of [1] to [4], which has at least a three-layer structure of an inner layer / barrier layer / outer layer.
[6] has at least a five-layer structure consisting of inner layer / barrier layer / intermediate layer / barrier layer / outer layer,
Polyester (A) 94 to 99.9 mass% in which the intermediate layer contains a dicarboxylic acid unit containing 80 mol% or more of terephthalic acid units and a diol unit containing 80 mol% or more of ethylene glycol units, and metaxylylene diamine unit In any one of [1] to [4], which is composed of a resin composition (E) containing 0.1 to 6% by mass of a polyamide (B) containing a diamine unit containing 70 mol% or more and a dicarboxylic acid unit Multilayer structure as described.
[7] The multilayer structure according to any one of [1] to [6], which is a preform.
[8] The multilayer structure according to any one of [1] to [6], which is a container obtained by blow molding a preform by a hot parison method or a cold parison method.
[9] The multilayer structure according to [7] or [8], which has a multilayer structure at least in the trunk portion.

  According to a preferred embodiment of the present invention, it has high gas barrier properties, is less likely to cause delamination due to falling or external impact, is easy to handle, and causes deterioration of the contents due to oxygen and deterioration of taste and flavor. It is possible to provide a multilayer structure that can be effectively prevented. The multilayer structure of the present invention can be suitably used as a container for packaging substances that dislike oxygen, such as beverages, foods, cosmetics, and pharmaceuticals, as a preform for the same, or the like.

It is a schematic fragmentary sectional view which shows an example of the three-layer structure which the multilayer structure of this invention has. It is a schematic fragmentary sectional view which shows an example of the 5 layer structure which the multilayer structure of this invention has. It is a schematic sectional drawing which shows the preform which is an example of the multilayer structure of this invention. It is a schematic sectional drawing which shows the bottle which is an example of the multilayer structure of this invention.

Hereinafter, the multilayer structure of the present invention will be specifically described.
The multilayer structure of the present invention is a multilayer structure having at least a multilayer structure including an inner layer, an outer layer, and at least one barrier layer located between the inner layer and the outer layer,
94 to 99.9 mass% of a polyester (A) in which the inner layer and the outer layer each independently contain a dicarboxylic acid unit containing 80 mol% or more of terephthalic acid units and a diol unit containing 80 mol% or more of ethylene glycol units, A resin composition (C) containing 0.1 to 6% by mass of a polyamide (B) containing a diamine unit containing 70 mol% or more of a metaxylylene diamine unit and a dicarboxylic acid unit,
1 to 40% by mass of a polyester (A) in which the barrier layer contains a dicarboxylic acid unit containing 80 mol% or more of terephthalic acid units and a diol unit containing 80 mol% or more of ethylene glycol units, and 70 metaxylylene diamine units It is characterized in that it is made of a resin composition (D) containing 60 to 99% by mass of polyamide (B) containing a diamine unit and a dicarboxylic acid unit containing mol% or more.

  In the present invention, in each layer of the inner layer, the outer layer, and the barrier layer located between the inner layer and the outer layer, a polyester (A) having a predetermined structural unit and a polyamide (B) are blended and used. By adjusting the quantitative ratio of polyester (A) to polyamide (B) within a predetermined range, the interlayer adhesion is enhanced while maintaining high barrier properties. Even if the barrier layer contains a barrier resin such as a metaxylylene group-containing polyamide in the barrier layer to enhance the barrier property, the barrier property is reduced if delamination is caused by a drop or an external impact, and the contents are Not only can it not be stored stably, it is also undesirable in terms of appearance. Therefore, in the present invention, it is easy to handle while maintaining high barrier properties by making it difficult to cause delamination due to falling or external impact, and deterioration of the contents due to oxygen and deterioration of taste and flavor It is an object of the present invention to provide a multilayer structure capable of effectively preventing the Hereinafter, the inner layer, the outer layer, and the barrier layer constituting the multilayer structure of the multilayer structure of the present invention will be specifically described.

1. Inner layer and outer layer
In the multilayer structure of the present invention, the inner layer and the outer layer are layers for holding the contents safely and stably, and have a role of protecting the barrier layer. Each of the inner layer and the outer layer used in the multilayer structure of the present invention may be one layer or two or more layers.

  In the present invention, the inner layer and the outer layer are each independently polyester (A) 94 to 99.9 containing a dicarboxylic acid unit containing 80 mol% or more of terephthalic acid units and a diol unit containing 80 mol% or more of ethylene glycol units. It is comprised from resin composition (C) containing 0.1-6 mass% of polyamide (B) which contains the diamine unit and the dicarboxylic acid unit which contain 70 mass% or more of metaxylylene diamine units, and mass%. Hereinafter, each component of the resin composition which comprises each layer of an inner layer and an outer layer is demonstrated.

[Polyester (A)]
The polyester (A) is a polyester containing a dicarboxylic acid unit containing 80 mol% or more of terephthalic acid units and a diol unit containing 80 mol% or more of ethylene glycol units, and the above dicarboxylic acid in the repeating structural unit of the polymer main chain It has ester bond {-C (= O) O-} comprised from a unit and the said diol unit.

The dicarboxylic acid unit constituting the polyester (A) contains at least 80 mol%, preferably at least 85 mol%, more preferably at least 87 mol%, still more preferably at least 90 mol% of terephthalic acid units. By containing the terephthalic acid unit in the above-mentioned amount ratio, the polyester (A) is unlikely to be amorphous, and when the multilayer structure is formed, heat shrinkage is difficult and heat resistance is improved. Although the upper limit in particular of the terephthalic acid unit contained in a dicarboxylic acid unit is not restrict | limited, 99.9 mol% or less is preferable and 95 mol% or less is more preferable.
Examples of dicarboxylic acids constituting dicarboxylic acid units other than terephthalic acid units include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, dodecanedicarboxylic acid, Tetradecanedicarboxylic acid, hexadecanedicarboxylic acid, 3-cyclobutanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 2,5 -Saturated aliphatic dicarboxylic acids exemplified by norbornane dicarboxylic acid, tricyclodecane dicarboxylic acid, dimer acid etc. or unsaturated aliphatic dicarboxylic acids exemplified by fumaric acid, maleic acid, itaconic acid etc. Or these Ester forming derivatives: orthophthalic acid, isophthalic acid, diphenic acid, 1,3-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7- Naphthalene dicarboxylic acid, biphenyl ketone dicarboxylic acid, 4,4′-biphenyl dicarboxylic acid, 4,4′-biphenyl sulfone dicarboxylic acid, 4,4′-biphenyl ether dicarboxylic acid, 1,2-bis (phenoxy) ethane-p, Aromatic dicarboxylic acids exemplified by p'-dicarboxylic acid, pamoinic acid, anthracene dicarboxylic acid and the like, and ester forming derivatives thereof and the like can be mentioned.
Among these, in particular, physical properties of polyester obtained by using aromatic dicarboxylic acids such as isophthalic acid, orthophthalic acid, naphthalene dicarboxylic acid, 4,4'-biphenyl dicarboxylic acid or ester-forming derivatives thereof It is preferable in point.
In addition, polyesters containing structural units derived from alicyclic difunctional compounds such as 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid are easy to produce, In addition, the drop impact strength and the transparency of the multilayer structure can be further improved, which is preferable. Among these, the use of 1,4-cyclohexanedicarboxylic acid which is readily available and has high drop impact strength is preferred.

The diol unit constituting the polyester (A) contains 80 mol% or more, preferably 85 mol% or more, more preferably 88 mol% or more, still more preferably 90 mol% or more of ethylene glycol units. By containing an ethylene glycol unit in the above-mentioned quantitative ratio, it is possible to obtain excellent gas crystallinity, gas barrier property, and strength for holding contents. The upper limit of the ethylene glycol unit contained in the diol unit is not particularly limited, and is, for example, 99 mol%.
When a diol unit other than an ethylene glycol unit is contained, examples of the diol constituting the diol unit include 1,2-propylene glycol, 1,3-propylene glycol, diethylene glycol, triethylene glycol, 1,2-butylene glycol, 3-butylene glycol, 2,3-butylene glycol, 1,4-butylene glycol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, methylpentanediol, 1,2-cyclohexanediol, 1,3 3-cyclohexanediol, 1,4-cyclohexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 1,4-cyclohexanediethanol, norbornene di-methane Tanol, tricyclodecanedimethanol, 1,10-decamethylene glycol, 2-butene-1,4-diol, 1,12-dodecanediol, polyethylene glycol, polytrimethylene glycol, polytetramethylene glycol, etc. Aliphatic glycols; hydroquinone, 4,4'-dihydroxybisphenol, 1,4-bis (β-hydroxyethoxy) benzene, 1,4-bis (β-hydroxyethoxyphenyl) sulfone, bis (p-hydroxyphenyl) 2) Ether, bis (p-hydroxyphenyl) sulfone, bis (p-hydroxyphenyl) methane, 1,2-bis (p-hydroxyphenyl) ethane, bisphenol A, bisphenol C, 2,5-naphthalenediol, isosorbide, 2 , 2,4,4-Tetrame Examples thereof include aromatic glycols exemplified by chill-1,3-cyclobutanediol, glycols obtained by adding ethylene oxide to these glycols, and the like.
Among these, in particular, 1,3-propylene glycol, 1,4-butylene glycol, 1,4-cyclohexanedimethanol and neopentyl glycol are preferably used.

In one embodiment of the present invention, as a copolymer component other than terephthalic acid / ethylene glycol contained in polyester (A), isophthalic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid At least one selected from the group consisting of diethylene glycol, neopentyl glycol, 1,4-cyclohexanedimethanol, 1,2-propanediol, 1,3-propanediol and 2-methyl-1,3-propanediol is It is preferable from the viewpoint of achieving both transparency and moldability. In particular, at least one selected from the group consisting of isophthalic acid, 2,6-naphthalenedicarboxylic acid, neopentyl glycol and 1,4-cyclohexanedimethanol is more preferable.
Among them, a copolyester containing a structural unit derived from isophthalic acid is excellent in moldability, and is also excellent in that it prevents the whitening of a molded article by slowing the crystallization rate. The proportion of the structural unit derived from isophthalic acid is preferably 1 to 10 mol%, more preferably 1 to 8 mol%, and still more preferably 1 to 6 mol% with respect to the total number of moles of the dicarboxylic acid unit.
In addition, a copolyester containing a structural unit derived from naphthalene dicarboxylic acid raises the glass transition point of the resin and improves the heat resistance, and absorbs ultraviolet rays, so that the multilayer structure is required to have resistance to ultraviolet rays. It is suitably used for manufacture. The proportion of the structural unit derived from naphthalenedicarboxylic acid is preferably 0.1 to 15 mol%, more preferably 1.0 to 10 mol%, with respect to the total number of moles of the dicarboxylic acid unit. By setting it as said ratio, it becomes possible to protect appropriately the content accommodated in a multilayer structure from an ultraviolet-ray. As a naphthalene dicarboxylic acid, a 2, 6- naphthalene dicarboxylic acid component is preferable because of easy production and high economic efficiency.

  In one embodiment of the present invention, in particular as the composition of the polyester (A), a combination of terephthalic acid / isophthalic acid // ethylene glycol, a combination of terephthalic acid // ethylene glycol / 1,4-cyclohexanedimethanol, terephthalic acid /// A combination of ethylene glycol / neopentyl glycol is preferred to achieve both transparency and moldability. As a matter of course, the polyester (A) may contain a small amount (5 mol% or less) of diethylene glycol produced by the dimerization of ethylene glycol during the esterification (ester exchange) reaction and the polycondensation reaction.

In one embodiment of the present invention, the polyester (A) may contain a structural unit derived from a monofunctional compound such as a monocarboxylic acid, a monoalcohol, or an ester-forming derivative thereof. Specific examples of these compounds include benzoic acid, o-methoxybenzoic acid, m-methoxybenzoic acid, p-methoxybenzoic acid, o-methylbenzoic acid, m-methylbenzoic acid, p-methylbenzoic acid, 2, 3 -Dimethylbenzoic acid, 2,4-dimethylbenzoic acid, 2,5-dimethylbenzoic acid, 2,6-dimethylbenzoic acid, 3,4-dimethylbenzoic acid, 3,5-dimethylbenzoic acid, 2,4,6 -Trimethylbenzoic acid, 2,4,6-trimethoxybenzoic acid, 3,4,5-trimethoxybenzoic acid, 1-naphthoic acid, 2-naphthoic acid, 2-biphenylcarboxylic acid, 1-naphthaleneacetic acid and 2-naphthaleneacetic acid Etc .; propionic acid, butyric acid, n-octanoic acid, n-nonanoic acid, myristic acid, pentadecanoic acid, stearic acid, oleic acid, linoleic acid Aliphatic monocarboxylic acids such as linolenic acid; ester-forming derivatives of these monocarboxylic acids, benzyl alcohol, 2,5-dimethylbenzyl alcohol, 2-phenethyl alcohol, phenols, aromatic alcohols such as 1-naphthol and 2-naphthol Aliphatic or alicyclic such as butyl alcohol, hexyl alcohol, octyl alcohol, pentadecyl alcohol, stearyl alcohol, polyethylene glycol monoalkyl ether, polypropylene glycol monoalkyl ether, polytetramethylene glycol monoalkyl ether, oleyl alcohol and cyclododecanol Formula monoalcohol etc. are mentioned.
Among these, benzoic acid, 2,4,6-trimethoxybenzoic acid, 2-naphthoic acid, stearic acid and stearyl alcohol are preferable from the viewpoint of the easiness of polyester production and their production cost. The ratio of the structural unit derived from the monofunctional compound is 5 mol% or less, preferably 3% or less, more preferably 1% or less, based on the total number of moles of all the structural units of the polyester (A). The monofunctional compound can function as end-capping of the end group or branched end of the polyester molecular chain, thereby suppressing excessive crosslinking of the polyester (A) and preventing gelation.

Furthermore, in one embodiment of the present invention, the polyester (A) contains, as a copolymerization component, a polyfunctional compound having at least three functional groups selected from a carboxyl group, a hydroxyl group and their ester forming groups. It is also good. Examples of polyfunctional compounds include trimesic acid, trimellitic acid, 1,2,3-benzenetricarboxylic acid, pyromellitic acid, 3,4,3 ', 4'-biphenyltetracarboxylic acid and 1,4,5 Polycarboxylic acids such as 1,8-naphthalenetetracarboxylic acid; alicyclic polycarboxylic acids such as 1,3,5-cyclohexanetricarboxylic acid; aliphatic polycarboxylic acids such as ethanetricarboxylic acid, propanetricarboxylic acid and butanetetracarboxylic acid Carboxylic acids; aromatic polyhydric alcohols such as 1,3,5-trihydroxybenzene; trimethylolmethane, trimethylolethane, trimethylolpropane, pentaerythritol, glycerin, hexanetriol and 1,3,5-cyclohexanetriol, etc. Aliphatic or alicyclic polyhydric alcohol; 4-hydro Chiisophthalic acid, 3-hydroxyisophthalic acid, 2,3-dihydroxybenzoic acid, 2,4-dihydroxybenzoic acid, 2,5-dihydroxybenzoic acid, 2,6-dihydroxybenzoic acid, protocatechuic acid, gallic acid and 2,4 And aromatic hydroxycarboxylic acids such as dihydroxyphenylacetic acid; aliphatic hydroxycarboxylic acids such as tartaric acid and malic acid; and their esters.
The proportion of constituent units derived from the polyfunctional compound is preferably 10 mol% or less, more preferably 5 mol% or less, still more preferably 3 mol% or less based on the total number of moles of all constituent units of the polyester (A). It is.
Among the above-mentioned compounds, preferred polyfunctional compounds include trimellitic acid, pyromellitic acid, trimesic acid, trimethylolpropane and pentaerythritol from the viewpoint of the easiness of production of the polyester (A) and the production cost.

In addition, in one embodiment of the present invention, the polyester (A) may contain at least one structural unit derived from a metal sulfonate.
The structural unit derived from metal sulfonate can be introduce | transduced into polyester (A) by using a metal sulfonate group containing compound as a copolymer component of polyester.
Metal sulfonate group-containing compound has the formula: is represented by X-R, X is a dicarboxylic acid or diol, R is -SO ₃ M. M is a metal in the +1 or +2 valence state which can be selected from Li, Na, Zn, Sn, K and Ca. Among these, Na or Li is preferable in terms of easy production. The metal sulfonate group-containing compound contains two or more functional groups, and R is directly bonded to a side chain such as a diol, an aromatic ring of a dicarboxylic acid X, or a methylene group.
As X in the formula, for example, aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid, naphthalene dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl-4, 4-dicarboxylic acid; oxalic acid, malonic acid, succinic acid, Linear aliphatic dicarboxylic acids such as glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid and sebacic acid; compounds obtained by removing one hydrogen atom from a compound selected from alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid Can be mentioned. Among these, isophthalic acid is preferable because of easy production.
Moreover, as X in the formula, ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, diethylene glycol, etc. Examples thereof include linear aliphatic glycols; cyclohexanediols such as 1,3-cyclohexanediol; and alicyclic diols such as cyclohexanedimethanol and the like, from which one hydrogen atom has been removed. Among these, ethylene glycol, diethylene glycol and cyclohexane diol are preferable.
Among these, in the present invention, it is particularly preferable to have a metal sulfoisophthalic acid unit introduced by a metal sulfonate group-containing compound in which X in the formula is isophthalic acid. By having the metal sulfoisophthalic acid unit, the compatibility between the polyester (A) and the polyamide (B) can be enhanced, and the transparency can be improved.
The amount ratio of metal sulfonate (-SO ₃ M) is preferably 0.1 mol% or more, more preferably 0.2 mol% or more, and further preferably, with respect to the total number of moles of all constituent units of polyester (A). Is preferably 0.4 mol% or more, preferably 10 mol% or less, more preferably 5 mol% or less, still more preferably 4 mol% or less, particularly preferably 2 mol% or less. The quantitative ratio of metal sulfonate can be measured by measuring the amount of sulfur and metal in the polyester (A) and converting it to a molar amount.

The polyester (A) can be produced by applying a known method such as direct esterification or transesterification.
Examples of the polycondensation catalyst to be used include known antimony compounds such as antimony trioxide and antimony pentoxide, germanium compounds such as germanium oxide, titanium compounds such as titanium acetate, and aluminum compounds such as aluminum chloride. Not limited to these.
As another production method, polyester (A) may be produced by adopting a method of transesterifying different types of polyester by methods such as long residence time and / or high temperature extrusion.

  The polyester (A) is a dimer of ethylene glycol component and may contain a small amount of diethylene glycol by-product units which are formed in a small amount in the process of producing the polyester. In order to maintain good physical properties of the multilayer structure of the present invention, the proportion of diethylene glycol units in the polyester (A) is preferably as low as possible. The proportion of the structural unit derived from diethylene glycol is preferably 3 mol% or less, more preferably 1 to 2 mol%, based on the total structural units of polyester (A).

  The moisture content of the polyester (A) is preferably 200 ppm or less, more preferably 100 ppm or less. The polyester (A) may be one which is dried and the like to reduce the moisture content before being formed into a multilayer structure.

  The intrinsic viscosity (value measured at 25 ° C. in a mixed solvent of phenol / 1,1,2,2-tetrachloroethane = 60/40 mass ratio) of the polyester (A) is not particularly limited, but usually 0.5 to 0.5 It is desirable that it is 2.0 dl / g, preferably 0.6 to 1.5 dl / g. When the intrinsic viscosity is 0.5 dl / g or more, the multilayer structure can exhibit the necessary mechanical properties as a structure.

  The polyester (A) used in the present invention may contain regenerated polyester, or materials derived from used polyester or industrially recycled polyester (for example, polyester monomers, catalysts and oligomers).

  The polyester (A) may be used alone or in combination of two or more.

  In the present invention, the polyester (A) is contained in the range of 94 to 99.9% by mass in the resin composition (C) constituting the inner layer and the outer layer. The ratio of polyester (A) in the resin composition (C) is preferably 94.5% by mass or more, more preferably 95.0% by mass or more, and preferably 99.5% by mass or less, more preferably Preferably it is 98.5 mass% or less, More preferably, it is 97.5 mass% or less.

[Polyamide (B)]
The polyamide (B) is a polyamide containing a diamine unit containing 70 mol% or more of metaxylylene diamine unit and a dicarboxylic acid unit, and is composed of the diamine unit and the dicarboxylic acid unit in the repeating structural unit of the polymer main chain. Have an amide bond {-NH-C (= O)-}.

  The diamine unit in the polyamide (B) contains 70 mol% or more, preferably 80 mol% or more, more preferably 90 mol% or more, still more preferably 95 mol% or more of metaxylylene diamine unit. By including the metaxylylene diamine unit in the above range, not only water resistance but also high strength and high elastic modulus, and excellent gas barrier properties can be exhibited, and molding of the resin composition containing polyamide (B) is possible. It can be made good.

  As diamine which comprises diamine units other than a meta xylylene diamine unit, aromatic diamines, such as ortho xylylene diamine, para xylylene diamine, and para phenylene diamine; 1,2-bis (aminomethyl) cyclohexane, 1,3- Alicyclic diamines such as bis (aminomethyl) cyclohexane and 1,4-bis (aminomethyl) cyclohexane; ethylenediamine, 1,3-propylenediamine, tetramethylenediamine, pentamethylenediamian, hexamethylenediamine, heptamethylenediamine Octamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylene, dodecamethylenediamine, 2-methyl-1,5-pentanediamine, 1-amino-3-aminomethyl-3,5,5-trimethylsilane Aliphatic diamines such as hexane; can be exemplified a polyether diamine having an ether bond represented by Huntsman Corp. JEFFAMINE and Erasutamin (all trade names), but are not limited to. These can be used singly or in combination of two or more. Among these, para-xylylene diamine is preferable.

［式（II−１）中、ｎは２〜１８の整数であり、式（II−２）中、Ａｒはアリーレン基である。］ The dicarboxylic acid unit constituting the polyamide (B) is not particularly limited, and an aliphatic dicarboxylic acid unit, an alicyclic dicarboxylic acid unit and an aromatic dicarboxylic acid unit are used. Among these, a linear aliphatic dicarboxylic acid unit represented by the following general formula (II-1) and an aromatic dicarboxylic acid unit represented by the following general formula (II-2) because of excellent heat resistance and molding processability It is preferable to include at least one dicarboxylic acid unit selected from Either one of the linear aliphatic dicarboxylic acid unit represented by the general formula (II-1) and the aromatic dicarboxylic acid unit represented by the following general formula (II-2) may be used, or a combination of these may be used. You may use.

[In the formula (II-1), n is an integer of 2 to 18, and in the formula (II-2), Ar is an arylene group. ]

  Respective proportions of the linear aliphatic dicarboxylic acid unit represented by the general formula (II-1) contained in the dicarboxylic acid unit constituting the polyamide (B) and the aromatic dicarboxylic acid unit represented by the general formula (II-2) Is not particularly limited, but from the viewpoint of the reactivity during polymerization, and the crystallinity and formability of the polyamide compound, the total amount in the dicarboxylic acid unit is preferably 50 mol% or more, more preferably 70 mol% or more, and further preferably Is 80 mol% or more, particularly preferably 90 mol% or more. When the linear aliphatic dicarboxylic acid unit and the aromatic dicarboxylic acid unit are used in combination, the total amount thereof may satisfy the above range.

  Examples of the dicarboxylic acid unit other than the dicarboxylic acid unit represented by the general formula (II-1) or (II-2) include oxalic acid, malonic acid, fumaric acid, maleic acid, 1,3-benzenediacetic acid, 1,4 Examples include, but are not limited to, dicarboxylic acid units obtained from dicarboxylic acids such as benzenediacetic acid.

  In the dicarboxylic acid unit in the polyamide (B), the content ratio of the linear aliphatic dicarboxylic acid unit to the aromatic dicarboxylic acid unit (linear aliphatic dicarboxylic acid unit / aromatic dicarboxylic acid unit) is particularly limited It is decided appropriately according to the use. For example, when it is intended to raise the glass transition temperature of the polyamide (B) and reduce the crystallinity of the polyamide (B), the linear aliphatic dicarboxylic acid unit / aromatic dicarboxylic acid unit is the sum of both units. Is preferably 0/100 to 60/40, more preferably 0/100 to 40/60, and still more preferably 0/100 to 30/70. Further, in order to lower the glass transition temperature of the polyamide (B) to impart flexibility to the polyamide (B), the linear aliphatic dicarboxylic acid unit / aromatic dicarboxylic acid unit is the sum of both units. When it is set to 100, it is preferably 40/60 to 100/0, more preferably 60/40 to 100/0, still more preferably 70/30 to 100/0.

In addition to imparting appropriate glass transition temperature and crystallinity to polyamide (B), when it is intended to impart appropriate flexibility, linear aliphatic dicarbon represented by General Formula (II-1) It is preferred to contain an acid unit.
In general formula (II-1), n represents an integer of 2 to 18, preferably 3 to 16, more preferably 4 to 12, and further preferably 4 to 8.
As a compound which comprises the linear aliphatic dicarboxylic acid unit shown by general formula (II-1), succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1, 10-decane Examples thereof include, but are not limited to, dicarboxylic acids, 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid and the like. These can be used alone or in combination of two or more.

The kind of the linear aliphatic dicarboxylic acid unit represented by the general formula (II-1) used in the present invention and the amount ratio thereof may be appropriately determined according to the application of the multilayer structure of the present invention.
From the viewpoint of maintaining heat resistance after heat sterilization in addition to imparting excellent gas barrier properties to the polyamide (B), it is selected from the group consisting of adipic acid units, sebacic acid units and 1,12-dodecanedicarboxylic acid units. The total amount of at least one selected from dicarboxylic acid units is preferably 50 mol% or more, more preferably 70 mol% or more, still more preferably 80 mol% or more, and particularly preferably 90 mol% or more.

  Moreover, in addition to imparting excellent gas barrier properties to polyamide (B), from the viewpoint of imparting thermal properties such as a suitable glass transition temperature and melting point, the adipic acid unit is contained in the linear aliphatic dicarboxylic acid unit. It is preferable to contain 50 mol% or more. In addition, from the viewpoint of imparting appropriate gas barrier properties and molding processability to the polyamide (B), it is preferable that the sebacic acid unit is contained in 50 mol% or more in the linear aliphatic dicarboxylic acid unit. Moreover, it is preferable to contain 50 mol% or more of 1,12-dodecane dicarboxylic acid units in a linear aliphatic dicarboxylic acid unit from a viewpoint of providing low water absorbency, weather resistance, and heat resistance.

The aromatic dicarboxylic acid represented by the above general formula (II-2) is intended to facilitate molding processability of the multilayer structure in addition to imparting further gas barrier properties to the polyamide (B) It is preferred to include a unit.
In general formula (II-2), Ar represents an arylene group. The arylene group is preferably an arylene group having 6 to 30 carbon atoms, more preferably 6 to 15 carbon atoms, and examples thereof include a phenylene group and a naphthylene group.
Examples of the compound capable of constituting the aromatic dicarboxylic acid unit represented by the general formula (II-2) include, but are not limited to, terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid. . These can be used alone or in combination of two or more.

The kind of the aromatic dicarboxylic acid unit represented by the general formula (II-2) used in the present invention and the amount ratio thereof may be appropriately determined according to the application of the multilayer structure of the present invention.
The aromatic dicarboxylic acid unit in the polyamide (B) is at least one selected from the group consisting of isophthalic acid units, terephthalic acid units, and 2,6-naphthalenedicarboxylic acid units in total in the aromatic dicarboxylic acid units. The content is preferably 50 mol% or more, more preferably 70 mol% or more, still more preferably 80 mol% or more, and particularly preferably 90 mol% or more. Among these, it is preferable to include isophthalic acid and / or terephthalic acid in the aromatic dicarboxylic acid unit. The content ratio of isophthalic acid unit to terephthalic acid unit (isophthalic acid unit / terephthalic acid unit) is not particularly limited and may be appropriately determined depending on the application. For example, from the viewpoint of lowering the appropriate glass transition temperature and crystallinity, when the total of both units is 100, it is preferably 0/100 to 100/0, more preferably 0/100 to 60/40, still more preferably 0. / 100 to 40/60, more preferably 0/100 to 30/70.

The polyamide (B) used in the present invention is not particularly limited as long as it is a polyamide containing a diamine unit containing 70 mol% or more of metaxylylene diamine unit and a dicarboxylic acid unit, but in one embodiment of the present invention And the mechanical properties are excellent, as the polyamide (B), a polyamide containing a diamine unit containing 70 mol% or more of metaxylylene diamine unit and a dicarboxylic acid unit containing 70 mol% or more of adipic acid unit is used Is preferred.
Further, in another embodiment of the present invention, in addition to the barrier property and the mechanical physical properties, from the viewpoint of good moldability, a diamine containing 70 mol% or more of metaxylylene diamine unit as polyamide (B) It is preferred to use a polyamide comprising units and dicarboxylic acid units comprising 70 to 99 mol% of adipic acid units and 1 to 30 mol% of isophthalic acid units.

The number average molecular weight (Mn) of the polyamide (B) is not particularly limited, but is preferably 5,000 or more, more preferably 10,000 or more, and still more preferably 15,000 or more. Moreover, 50,000 or less is preferable, More preferably, it is 45,000 or less, More preferably, it is 40,000 or less. When the number average molecular weight of the polyamide (B) is in the above range, the amount of unreacted material as the polyamide is small, and the properties are stable. The number average molecular weight of the polyamide (B) can be determined from the quantitative values of the terminal amino group concentration and the terminal carboxyl group concentration by the following equation.
Number average molecular weight = 2 × 1,000,000 / ([NH ₂ ] + [COOH])
[NH ₂ ]: terminal amino group concentration (μeq / g)
[COOH]: terminal carboxyl group concentration (μeq / g)

  The polyamide (B) can be produced by polymerizing a diamine component constituting a diamine unit and a dicarboxylic acid component constituting a dicarboxylic acid unit. The degree of polymerization can be controlled by adjusting the polycondensation conditions and the like. During the polycondensation, a small amount of monoamine or monocarboxylic acid may be added as a molecular weight modifier. Further, in order to suppress the polycondensation reaction to obtain a desired degree of polymerization, the ratio (molar ratio) of the diamine component and the carboxylic acid component constituting the polyamide may be adjusted to be shifted from one.

  Examples of the polycondensation method of the polyamide (B) include, but are not limited to, a reactive extrusion method, a pressurized salt method, an atmospheric pressure dropping method, a pressurized dropping method and the like. Among these, the normal pressure dropping method and the pressurized dropping method are preferable in terms of cost merit because no solvent is used, and the normal pressure dropping method is particularly preferably used. When the reaction temperature is as low as possible, yellowing and gelation of the polyamide resin can be suppressed, and a polyamide resin having stable properties can be obtained.

The normal pressure dropping method is a method in which a dicarboxylic acid component is heated and melted under normal pressure, a diamine component is continuously dropped, and polycondensation is performed while removing condensation water. In this method, the polycondensation reaction is carried out while raising the temperature of the reaction system so that the reaction temperature does not fall below the melting point of the polyamide compound to be produced. The atmospheric pressure drop method does not use water for dissolving salts compared to the pressurized salt method, so the yield per batch is large, and the vaporization and condensation of the raw material components are not required. The decrease is small and the process time can be shortened.
In the pressure drop method, first, a dicarboxylic acid component is charged in a polycondensation can, heated and melted, and then the diamine component is continuously dropped while preferably pressurizing the inside of the can to about 0.3 to 0.4 MPaG, and condensation is performed. It is a method of polycondensation while removing water. In this method, the polycondensation reaction is carried out while raising the temperature of the reaction system so that the reaction temperature does not fall below the melting point of the polyamide compound to be produced. When the set molar ratio is reached, the dripping of the diamine component is finished, and while raising the pressure in the can gradually to normal pressure, the temperature is raised to about the melting point + 10 ° C of the polyamide (B) and held. While maintaining the temperature as it is while continuing the polycondensation. When the constant stirring torque is reached, the inside of the can is pressurized to about 0.3 MPaG with nitrogen to recover the polyamide (B).
The melt viscosity of the polyamide (B), that is, the method of adjusting the number average molecular weight is, in addition to the method of determining the polymerization end point at the stirring torque in the polymerization method described above, There is a method of setting the target number average molecular weight by adjusting by shifting from the above.

In the polycondensation of polyamide, it is preferable to add a phosphorus atom-containing compound from the viewpoint of promoting the amidation reaction.
Examples of phosphorus atom-containing compounds include phosphinic acid compounds such as dimethylphosphinic acid and phenylmethylphosphinic acid; hypophosphorous acid, sodium hypophosphite, potassium hypophosphite, lithium hypophosphite, magnesium hypophosphite, Calcium hypophosphite, hypophosphite compounds such as ethyl hypophosphite; phosphonic acid, sodium phosphonate, potassium phosphonate, lithium phosphonate, lithium phosphonate, potassium phosphonate, magnesium phosphonate, calcium phosphonate, phenyl phosphonic acid, ethyl phosphonic acid Phosphoric acid compounds such as sodium phenylphosphonate, potassium phenylphosphonate, lithium phenylphosphonate, diethyl phenylphosphonate, sodium ethylphosphonate, potassium ethylphosphonate; phosphonites, sodium phosphonites, phosphonites Lithium phosphonite, potassium phosphonite, magnesium phosphonite, calcium phosphonite, phenylphosphonite, sodium phenylphosphonite, potassium phenylphosphonite, lithium phenylphosphonite, ethyl phenylphosphonite and the like Phosphinic acid compound; phosphorous acid, sodium phosphite, sodium phosphite, lithium phosphite, potassium phosphite, magnesium phosphite, calcium phosphite, triethyl phosphite, triphenyl phosphite, pyrophosphorus Phosphoric acid compounds such as phosphoric acid and the like can be mentioned.
Among them, metal hypophosphites such as sodium hypophosphite, potassium hypophosphite and lithium hypophosphite are particularly preferably used because they are highly effective in promoting the amidification reaction and excellent in the color preventing effect. Particularly preferred is sodium hypophosphite. In addition, the phosphorus atom containing compound which can be used by this invention is not limited to these compounds.
The addition amount of the phosphorus atom-containing compound is preferably 0.1 to 1000 ppm, more preferably 1 to 600 ppm, still more preferably 5 to 400 ppm in terms of the phosphorus atom concentration in the polyamide. If it is 0.1 ppm or more, the polyamide is less likely to be colored during polymerization, and the transparency becomes high. When the amount is 1000 ppm or less, the polyamide is less likely to gel, and mixing of the fish eye into the molded product which is considered to be caused by the phosphorus atom-containing compound can be reduced, and the appearance of the molded product is improved.

In addition, it is preferable to add an alkali metal compound in combination with a phosphorus atom-containing compound in a polycondensation system of polyamide. In order to prevent coloring of the polyamide during polycondensation, it is necessary to have a sufficient amount of a phosphorus atom-containing compound, but in some cases, the gelation of the polyamide may be caused, so the amidization reaction rate is adjusted. For the purpose of coexistence, it is preferable to coexist an alkali metal compound.
As the alkali metal compound, alkali metal hydroxide, alkali metal acetate, alkali metal carbonate, alkali metal alkoxide and the like are preferable. Specific examples of the alkali metal compound that can be used in the present invention include lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, lithium acetate, sodium acetate, potassium acetate, rubidium acetate, cesium acetate Although sodium methoxide, sodium ethoxide, sodium propoxide, sodium butoxide, potassium methoxide, lithium methoxide, sodium carbonate and the like can be mentioned, they can be used without being limited to these compounds. The ratio of the phosphorus atom-containing compound to the alkali metal compound is, from the viewpoint of controlling the polymerization rate or from the viewpoint of reducing the yellowness, phosphorus atom-containing compound / alkali metal compound = 1.0 / 0.05 to 1.0 / The range of 1.5 is preferable, More preferably, it is 1.0 / 0.1-1.0 / 1.2, More preferably, it is 1.0 / 0.2-1.0 / 1.1.

  In the present invention, the polyamide (B) is contained in an amount of 0.1 to 6% by mass in the resin composition (C) constituting the inner layer and the outer layer. The blending amount of the polyamide (B) in the resin composition is preferably 0.5% by mass or more, more preferably 1.5% by mass or more, still more preferably 2.5% by mass or more, and preferably 5 .5 mass% or less, more preferably 5.0 mass% or less.

  In the present invention, various additives may be added to the resin composition (C) constituting the inner layer and the outer layer as long as the characteristics of the present invention are not impaired. For example, polyester other than polyester (A), polyamide other than polyamide (B), polyolefin, phenoxy resin, and other resins can be blended one or more kinds. Inorganic fillers such as glass fibers and carbon fibers; plate-like inorganic fillers such as glass flakes, talc, kaolin, mica, montmorillonite, organic clay, impact modifiers such as various elastomers, crystal nucleating agents Lubricants such as fatty acid amide type and fatty acid amide type compounds; organic or inorganic halogen type compounds, hindered phenol type, hindered amine type, hydrazine type, sulfur type compounds, antioxidants such as phosphorus type compounds, etc .; coloring inhibitors, benzotriazole UV absorbers, release agents, plasticizers, colorants, UV absorbers, infrared absorbers (reheat additives) to accelerate heating of preforms and shorten cycle time during molding, etc. Can be illustrated. The additives may be used alone or in combination of two or more as needed. The blending amount of the additive in the resin composition (C) constituting the inner layer and the outer layer is not particularly limited as long as the characteristics of the present invention are not impaired.

  In the present invention, the resin composition that constitutes the inner layer and the resin composition that constitutes the outer layer may have exactly the same composition, and the type and amount ratio of the polyester (A) and the polyamide (B), The composition may have different compositions depending on the types and proportions of various additives. However, it is preferable that the resin composition which comprises an inner layer and the resin composition which comprises an outer layer have the same composition from the point that manufacture is easy and it acquires the outstanding delamination strength.

2. Barrier Layer In the multilayer structure of the present invention, the barrier layer is a layer which is located between the inner layer and the outer layer and prevents oxygen from entering the container through the wall of the container from the outside of the container. The barrier layer used in the multilayer structure of the present invention may be a single layer or two or more layers.

  In the present invention, the barrier layer comprises 1 to 40% by mass of polyester (A) containing a dicarboxylic acid unit containing 80 mol% or more of terephthalic acid units and a diol unit containing 80 mol% or more of ethylene glycol units, and metaxylylene It is comprised from the resin composition (D) containing 60-99 mass% of polyamides (B) containing the diamine unit which contains 70 mol% or more of amine units, and a dicarboxylic acid unit. The polyester (A) and the polyamide (B) are as described in the polyester (A) and the polyamide (B) used for the resin composition (C) constituting the inner layer and the outer layer, respectively.

  The polyester (A) used for the resin composition (D) constituting the barrier layer may be a polyester containing a dicarboxylic acid unit containing 80 mol% or more of terephthalic acid units and a diol unit containing 80 mol% or more of ethylene glycol units. There is no particular limitation. It may have the same composition as the polyester (A) used in the resin composition (C) constituting the inner layer and the outer layer, or may have a different composition. However, polyester (A) used for the resin composition (D) constituting the barrier layer constitutes the inner layer and the outer layer in that the delamination can be more effectively prevented and the production is easy. It is preferable to have the same composition as the polyester (A) used for the resin composition (C).

  The polyamide (B) used for the resin composition (D) constituting the barrier layer is not particularly limited as long as it contains a diamine unit containing 70 mol% or more of m-xylylene diamine unit and a dicarboxylic acid unit. It may have the same composition as the polyamide (B) used in the resin composition (C) constituting the inner layer and the outer layer, or may have a different composition. However, the polyamide (B) used for the barrier layer is used for the resin composition (C) constituting the inner layer and the outer layer in that the delamination can be more effectively prevented and the production is easy. It is preferable to have the same composition as the polyamide (B).

In the present invention, the compounding amount of the polyester (A) contained in the resin composition (D) constituting the barrier layer is 1 to 40 mass, preferably 2 mass% or more, more preferably 3 mass% or more, More preferably, it is 5% by mass or more, particularly preferably 15% by mass or more, and preferably 35% by mass or less, more preferably 25% by mass or less.
In addition, the blending amount of polyamide (B) contained in the resin composition (D) constituting the barrier layer is 60 to 99% by mass, preferably 65% by mass or more, more preferably 75% by mass or more. Also preferably, it is 98% by mass or less, more preferably 97% by mass or less, still more preferably 95% by mass or less.
By including the polyester (A) and the polyamide (B) in the above range in the resin composition (D) constituting the barrier layer, it is possible to maintain the high barrier properties while peeling off against falling or external impact. It is hard to produce and can obtain a multilayer structure excellent in impact resistance.

  In the present invention, various additives may be added to the resin composition (D) constituting the barrier layer as long as the characteristics of the present invention are not impaired. As an additive which can be mix | blended with a barrier layer, the thing similar to the additive used for the resin composition (C) which comprises an inner layer and an outer layer can be used. The additives may be used alone or in combination of two or more as needed.

  When the multilayer structure of the present invention has two or more barrier layers, the resin composition (D) constituting the barrier layer may have the same composition or may have different compositions. .

  The multilayer structure of the present invention has at least in part a multilayer structure including the above-mentioned inner layer, outer layer and at least one barrier layer located between the inner layer and the outer layer, and in the multilayer structure, the inner layer, outer layer And each layer of the barrier layer is composed of a resin composition containing polyester (A) and polyamide (B) at a predetermined ratio, thereby improving interlayer adhesion while maintaining high barrier properties, and dropping or from the outside It has a structure in which delamination is unlikely to occur due to the impact of

  The multilayer structure of the multilayer structure of the present invention is not particularly limited as long as it has an inner layer, an outer layer and at least one barrier layer located between the inner layer and the outer layer, but the object of the present invention is impaired. To the extent there may be other layers including adhesive layer, protective layer, barrier coating layer and printing layer etc.

  In one embodiment of the present invention, the multilayer structure of the multilayer structure of the present invention preferably has, for example, a three-layer structure of inner layer 1 / barrier layer 2 / outer layer 3 as shown in FIG.

When the multilayer structure of the present invention has two or more barrier layers, an intermediate layer may be provided between the barrier layer and the barrier layer. For example, in one embodiment of the present invention, the multilayer structure of the multilayer structure of the present invention has a five-layer structure of inner layer 1 / barrier layer 2A / intermediate layer 4 / barrier layer 2B / outer layer 3 as shown in FIG. It is preferable to have. The composition of the resin composition (D) constituting the plurality of barrier layers may be the same or different.
As the intermediate layer, the interlayer adhesion with each barrier layer is good, and the strength of the structure can be maintained, and further, since the molding processability is excellent, a dicarboxylic acid unit containing 80 mol% or more of terephthalic acid unit and Polyester (A) 94 to 99.9% by mass containing a diol unit containing 80 mol% or more of ethylene glycol units, and polyamide containing a diamine unit containing 70 mol% or more of metaxylylene diamine units and a dicarboxylic acid unit ( B) A layer composed of a resin composition (E) containing 0.1 to 6% by mass is preferably used.
The polyester (A) and the polyamide (B) contained in the resin composition (E) and the ratio thereof are the same as the resin composition (C) constituting the inner layer and the outer layer, and the preferred embodiment and the range of the preferred ratio The same is true for etc. As a resin composition (E) which comprises an intermediate | middle layer, what has the same composition as the resin composition (C) which comprises an inner layer and an outer layer can also be used, and comprises an inner layer and an outer layer in said range. You may use what has a composition different from a resin composition (C). A plurality of barrier layers are laminated while improving interlayer adhesion between the barrier layer / intermediate layer / barrier layer by having an intermediate layer made of the resin composition (E) between the barrier layer and the barrier layer. And the barrier properties of the multilayer structure can be further enhanced.
In addition, if it is a range which does not impair the object of the present invention, you may have layers other than the above, for example, an adhesive layer, an oxygen absorption layer, etc. as an intermediate layer.

  In the multilayer structure of the present invention, the thickness of the inner layer, the outer layer, the barrier layer, and the intermediate layer may be appropriately selected according to the application and purpose of the multilayer structure.

  The proportion of the barrier layer in the multilayer structure of the present invention is not particularly limited, but in total, preferably 1% by mass or more, more preferably 2% by mass or more, further preferably, based on the total mass of the multilayer structure. When the content is 3% by mass or more, preferably 20% by mass or less, more preferably 15% by mass or less, and further preferably 10% by mass or less, a multilayer structure having a good barrier property can be obtained.

  The multilayer structure of the present invention can be suitably used as various containers or a preform thereof. In particular, it is suitable as a container for packaging substances that dislike oxygen, such as beverages, foods, cosmetics and medicines, or a preform thereof.

The shape of the multilayer structure of the present invention is not particularly limited, and may be any shape such as a bottle, a deep-draw container, a cup-like container or a preform (preform) thereof according to the application and purpose. . As a shape of a bottle, the shape of a general plastic bottle is mentioned preferably.
When the multilayer structure of the present invention is various containers, the thickness of the inner layer is preferably 0.01 mm or more, more preferably 0.03 mm or more, still more preferably 0.05 mm or more, and preferably 2.0 mm. More preferably, it is 1.5 mm or less, still more preferably 1.0 mm or less.
In addition, the thickness of the outer layer is preferably 0.01 mm or more, more preferably 0.05 mm or more, still more preferably 0.05 mm or more, and preferably 2.0 mm or less, more preferably 1.5 mm or less, more preferably Is less than 1.0 mm.
Further, the thickness of the barrier layer is preferably 0.005 mm or more, more preferably 0.01 mm or more, further preferably 0.02 mm or more, and preferably 0.2 mm or less, more preferably 0.15 mm or less, further Preferably it is 0.1 mm or less. When two or more barrier layers are provided, the total thickness of each barrier layer preferably has the above thickness.
Further, in the case of having two or more barrier layers and having an intermediate layer between the barrier layer and the barrier layer, the thickness of the intermediate layer is preferably 0.01 mm or more, more preferably 0.03 mm or more More preferably, it is 0.05 mm or more, Preferably, it is 2.0 mm or less, More preferably, it is 1.5 mm or less, More preferably, it is 1.0 mm or less.

  The volume of the multilayer structure of the present invention is preferably 0.1 to 2.0 L, preferably 0.2 to 1.5 L, and 0.3 to 1.0 L in view of the storage property of the contents. It is further preferred that

The thickness of the multilayer structure in the case where the multilayer structure of the present invention is various containers is not particularly limited and may be suitably selected in accordance with the application and purpose, but usually the range of 0.2 to 4.0 mm is preferable.
When the multilayer structure of the present invention is a preform, the container after blow stretching may be appropriately selected so as to have the above thickness.

  The multilayer structure of the present invention comprises, for example, the resin composition (C) constituting the inner layer and the outer layer from the injection cylinder on the skin side and the barrier layer using an injection molding machine having two injection cylinders. The resin composition (D) can be obtained as a multilayer preform by injecting the resin composition (D) from the injection cylinder on the core side through the mold hot runner into the mold cavity. Further, by subjecting the obtained multilayer preform to further biaxial stretch blow molding by a known method, it can be obtained as a molded article having an arbitrary shape. By this method, a multilayer structure having an arbitrary bottle shape can be obtained.

  As a biaxial stretch blow molding method of a multilayer preform, generally known methods such as so-called cold parison method or hot parison method can be used. For example, it is axially stretched by mechanical means such as heating the surface of the multilayer preform to 80 to 120 ° C. and then pressing with a core rod insert, and then blowing high-pressure air of usually 2 to 4 MPa and stretching in the lateral direction The method of blow molding is mentioned. Alternatively, there is a method of crystallizing the mouth of the multilayer preform, heating the surface to 80 to 120 ° C., and then blow molding in a mold at 90 to 150 ° C.

  The heating temperature of the multilayer preform is usually 80 to 120 ° C., preferably 90 to 110 ° C. If the heating temperature is lower than 80 ° C., the heating may be insufficient, and the inner layer, the outer layer or the barrier layer, and further the intermediate layer may be cold-stretched and whitened. If the temperature is higher than 120 ° C., the barrier layer crystallizes and whitens, which is not preferable. Furthermore, the delamination resistance performance may be reduced.

For example, a multilayer structure which is a blow-molded body having a three-layer structure can be obtained by biaxially stretch blow molding a multilayer preform having a three-layer structure by a known method.
The method for producing a multilayer preform having a three-layer structure is not particularly limited, and known methods can be used. For example, in the step of injecting the resin composition (C) constituting the inner layer and the outer layer from the skin side injection cylinder and injecting the resin composition (D) constituting the barrier layer from the core side injection cylinder, first, the inner layer and the outer layer Resin composition (C) constituting the barrier layer, and then simultaneously injecting the resin composition (D) constituting the barrier layer and the resin composition (C) constituting the inner layer and the outer layer, and then the inner layer and the outer layer By injecting the necessary amount of the resin composition (C) to fill the mold cavity, a multilayer preform of a three-layer structure (inner layer / barrier layer / outer layer) can be manufactured.
Also, for example, a multilayer structure which is a blow-molded body having a five-layer structure can be obtained by biaxially stretch blow molding a multilayer preform having a five-layer structure by a known method.
For example, when the resin composition constituting the inner layer and the outer layer and the resin composition constituting the intermediate layer have the same composition, first, the resin composition (C) constituting the inner layer, the intermediate layer and the outer layer (C) ( Alternatively, the resin composition (E) is injected, and then the resin composition (D) constituting the barrier layer is injected alone, and finally the resin composition (C) constituting the inner layer, the intermediate layer and the outer layer is required. A multilayer preform of 5-layer structure (inner layer / barrier layer / intermediate layer / barrier layer / outer layer) can be manufactured by injection to fill the mold cavity.
When the resin composition (C) constituting the inner layer and the outer layer and the resin composition (E) constituting the intermediate layer have different compositions, first, the resin composition (C) constituting the inner layer and the outer layer The resin composition (D) which is injected from the injection cylinder, and then the barrier layer is separately injected from another injection cylinder, and finally the resin composition (E) which constitutes the intermediate layer is injected in the necessary amount to form a cavity. The multi-layer preform of 5-layer structure (inner layer / barrier layer / intermediate layer / barrier layer / outer layer) can be manufactured by satisfying-.
The method of producing the multilayer preform is not limited to the above method. A person skilled in the art can produce a multilayer preform having a desired multilayer structure while referring to the above method.

In another preferred embodiment of the present invention, the multilayer structure of the present invention forms a multilayer sheet by a conventionally known method (extrusion lamination method, coextrusion method, fusion method using heat, etc.) and heats this sheet. The desired shape may be obtained by molding. By this method, a multilayer structure having an arbitrary deep drawing shape or cup shape can be obtained.
The method for producing the multilayer sheet is not particularly limited, but a co-extrusion method is preferable in terms of production efficiency. In the co-extrusion method, two or more extruders are used, and the inner layer and the outer layer are laminated on both surfaces in a multi-manifold die before extruding the barrier layer from the die lip, and the multilayer structure of the present invention is simultaneously extruded from the die lip. Is a method of obtaining a multilayer sheet which is a precursor of
As a method of thermoforming the multilayer sheet which is the obtained precursor, and making it a multilayer structure, although general vacuum forming, pressure forming, etc. are mentioned, it is not restricted to these.

The multilayer structure of the present invention may have at least a multilayer structure including an inner layer, an outer layer, and at least one barrier layer located between the inner layer and the outer layer, and a multilayer structure is partially formed. There may be parts that are not included.
For example, if the multilayer structure of the present invention has the shape of a preform as shown in FIG. 3 or if it has the shape of a bottle as shown in FIG. It is only necessary that the barrier layer 2 be present (ie, in the body, it should have a three-layer structure of inner layer 1 / barrier layer 2 / outer layer 3) up to near the tip of the plug or near the bottom. May not extend.
The barrier layer does not necessarily have to be a continuous layer, and may be a discontinuous layer as long as the barrier property is not significantly impaired. In the case where the barrier layer is a discontinuous layer, for example, the region where the barrier layer is present and the region where the barrier layer is not present are repeatedly arranged in stripes or strips in the body of the container to enhance the peeling prevention effect. Is desirable.
The same applies to the case where the multilayer structure of the present invention is a deep drawn container, a cup-shaped container or the like.

The multilayer structure of the present invention prevents oxygen from entering from the outside of the container, is less likely to cause delamination due to dropping or impact from the outside, is easy to handle, hardly causes appearance defects, and stabilizes the contents Can be stored.
In addition, the multilayer structure of the present invention is less likely to cause delamination due to falling or impact, and the content can be stably stored even in the shape including the uneven portion and the bent portion where delamination easily occurs. The shape of the structure is not limited to the shape having a small number of asperities and inflections, and has an advantage that the degree of freedom in design is increased.

  The multilayer structure of the present invention is suitable as, for example, a container or a preform thereof for packaging an oxygen-dissident substance such as beverage, food, cosmetics and medicine. For example, liquid drinks such as carbonated drinks, juices, water, milk, sake, whiskey, shochu, coffee, tea, jelly drinks, health drinks, etc .; seasoning liquids, sauces, soy sauce, dressings, liquid soup seasonings; liquid soup etc. Liquid-based food products; Various solid-based food products; Liquid or solid pharmaceuticals or quasi-drugs; Suitable for storage and preservation of various articles such as cosmetics such as lotions, cosmetic emulsions, hair setting agents, hair dyes and shampoos Used for

  Moreover, before and after the filling of these articles, sterilization of the multilayer structure and contents can be performed in a form suitable for the articles to be contents. The sterilization method includes hot water treatment at 100 ° C. or lower, hot water treatment at 100 ° C. or higher, heat sterilization such as ultra-high temperature heat treatment at 130 ° C. or higher, electromagnetic wave sterilization such as ultraviolet rays, micro breakage, gamma rays, etc., ethylene oxide Etc., and chemical sterilization of hydrogen peroxide and hypochlorous acid, etc.

  Hereinafter, the present invention will be more specifically described using examples and comparative examples, but the present invention is not limited to these examples.

  In each of the Examples and Comparative Examples, as will be described later, the oxygen permeability of the obtained bottle is produced as a preform and a bottle, which are a multilayer structure having at least a three-layer structure of an inner layer, an outer layer and a barrier layer. The delamination resistance and body haze were measured and evaluated by the following methods.

(1) Oxygen permeability (OTR)
The oxygen permeability test by MOCON method was performed according to ASTM D3985. MOCON OX-TRAN 2/61 was used for measurement. A 500 mL bottle obtained in each Example and Comparative Example is filled with 100 mL of water, and the temperature is 23 ° C., the internal humidity of the bottle is 100% RH, and the external humidity is 50% RH under an oxygen partial pressure of 0.21 atm. The nitrogen content of 1 atm was circulated at 20 mL / min through the inside of the bottle, and measurement was carried out by detecting oxygen contained in nitrogen after circulation through the inside of the bottle with a coulometric sensor. The lower the value, the smaller the amount of oxygen permeation and the better the gas barrier properties.

(2) Delamination resistance Based on ASTM D2463-95 Procedure B, the delamination height (minimum drop distance at which delamination occurs) was determined by a drop test of a bottle according to the following method.
First, the bottle obtained in each Example and Comparative Example was filled with 500 mL of colored water, capped, and allowed to stand at 5 ° C. for 24 hours. Thereafter, the bottle was vertically dropped from a predetermined height through a round cylinder so that the bottom portion was in contact with the floor. Since the locations where the layers were delaminated became cloudy and could be visually distinguished, the presence or absence of delamination of the bottle was visually determined.
In addition, it was assumed that delamination occurred even in a part of the delaminated bottles. The drop height interval was increased by 15 cm. The number of test bottles was 30.

(3) Torsional body haze About the bottle obtained by each Example and the comparative example, the trunk | drum which has 3 layer structure of an inner layer, a barrier layer, and an outer layer was cut out, and all the layers were accumulated in the state which the measurement site | part did not peel. The measurement was performed by the transmission method using “SH7000” manufactured by Nippon Denshoku Kogyo Co., Ltd. (using a 12 V / 50 W halogen lamp as a light source) according to JIS K7136.

Example 1
Using an injection molding machine (manufactured by Sumitomo Heavy Industries, type DU130CI) having two injection cylinders and a two-piece mold (manufactured by Kortec), under the conditions shown below, (Y) / (X) / ( A preform having in part a three-layer structure consisting of Y) was produced.
First, as a material constituting the layer (Y) to be the inner layer and the outer layer, polyester (A1) (isophthalic acid copolymerized polyethylene terephthalate (polyethylene terephthalate-isophthalate copolymer resin, manufactured by Nippon Unipet Co., Ltd.), trade name "Unipet BK- 2180 ′ ′)) and resin composition (C) obtained by blending polyamide (B1) (polymetaxylylene adipamide (Mitsubishi Gas Chemical Co., Ltd., MX nylon S 6007) in the proportions described in Table 1) from the injection cylinder Then, a resin composition (D) constituting the layer (Y) from another injection cylinder, the resin composition (D) blended in the proportion described in Table 1 as a material constituting the layer (X) to be the barrier layer C) simultaneously with the injection, and finally injecting the necessary amount of the resin composition (C) constituting the layer (Y) to fill the cavity (Y) / (X) / (Y). Preform shape to obtain a parison (27 g) having a portion of three-layer structure of the full-length 95 mm, outer diameter 22 mm, was thick 4.2 mm.
Skin side injection cylinder temperature: 280 ° C
Core side injection cylinder temperature: 280 ° C
In-mold resin channel temperature: 290 ° C
Mold cooling water temperature: 15 ° C
Cycle time: 40s
In addition, although the material which comprises layer (X) uses as a raw material the resin mixture (D) which blended polyester (A1) and polyamide (B1), these raw materials are melt-kneaded in an injection molding machine. It is a resin composition (D). Similarly, the material constituting the layer (Y) is made of a resin mixture (C) containing a polyester (A1) and a polyamide (B1) as a raw material, but these raw materials are melt-kneaded in an injection molding machine It is a resin composition (C).

The obtained preform was biaxially stretch blow-molded by a biaxial stretch blow molding apparatus (manufactured by Frontier, model EFB1000ET) to obtain a petaloid-type bottle. The total length of the bottle is 223 mm, the outer diameter is 65 mm, the internal volume is 500 mL, and the bottom is petaloid-shaped. No dimples were provided on the body. The biaxial stretching blow molding conditions are as shown below. The proportion of the layer (X) to the total mass of the obtained bottle was 3% by mass.
Preform heating temperature: 108 ° C
Extension rod pressure: 0.5MPa
Primary blow pressure: 0.7MPa
Secondary blow pressure: 2.5MPa
Primary blow delay time: 0.34 sec
Primary blow time: 0.30 sec
Secondary blow time: 2.0 sec
Blow exhaust time: 0.6 sec
Mold temperature: 30 ° C
The oxygen barrier properties, the delamination height and the body haze of the obtained bottle were evaluated and are shown in Table 1.

Examples 2 to 8
A preform was prepared in the same manner as in Example 1 except that the composition described in Table 1 was used as the resin composition (C) constituting layer (Y) and the resin composition (D) constituting layer (X). The bottle was obtained by molding and further secondary stretch blow. The oxygen barrier properties, the delamination height and the body haze of the obtained bottle were evaluated and are shown in Table 1.

<Comparative Examples 1 to 7>
A preform was prepared in the same manner as in Example 1 except that the composition described in Table 1 was used as the resin composition (C) constituting layer (Y) and the resin composition (D) constituting layer (X). The bottle was obtained by molding and further secondary stretch blow. The oxygen barrier properties, the delamination height and the body haze of the obtained bottle were evaluated and are shown in Table 2.

Examples 9 to 14
A resin composition (C) constituting the layer (Y) and a resin composition (D) constituting the layer (X) by changing the ratio of the layer (X) to the total mass of the bottle from 3 mass% to 5 mass% A preform was formed in the same manner as in Example 1 except that the composition described in Table 3 was used, and a bottle was obtained by further secondary stretch blowing. The oxygen barrier properties, the delamination height and the body haze of the obtained bottle were evaluated and are shown in Table 3.

<Comparative Examples 8 to 11>
A resin composition (C) constituting the layer (Y) and a resin composition (D) constituting the layer (X) by changing the ratio of the layer (X) to the total mass of the bottle from 3 mass% to 5 mass% A preform was molded in the same manner as in Example 1 except that the composition described in Table 4 was used, and a bottle was obtained by further secondary stretch blowing. The oxygen barrier properties, the delamination height and the body haze of the obtained bottles were evaluated and are shown in Table 4.

Example 15
Of the resin composition (C) constituting the layer (Y), the polyester (A1) is a polyester (A2) (polyethylene terephthalate-sodium sulfoisophthalate copolymer resin, intrinsic viscosity = 0.8 dl / g, dicarboxylic acid 100 mol A resin composition (D) comprising a layer (X) which is converted to a polyethylene terephthalate resin copolymerized with 2.0 mol% of isophthalic acid and 0.45 mol% of sodium 5-sulfoisophthalate with respect to 100% Among them, a preform was formed in the same manner as in Example 1 except that the polyester (A1) was changed to the polyester (A2) and the composition described in Table 5 was used, and a second stretching blow was performed to obtain a bottle . The oxygen barrier properties, the delamination height and the body haze of the obtained bottle were evaluated and are shown in Table 5.

  As shown in Tables 1 to 5, it was found that the bottles of the examples of the present invention had high barrier properties, and the peeling height showing interlayer adhesion was dramatically improved as compared with those of the comparative examples. Moreover, the torso haze was also within the allowable range. On the other hand, in Comparative Examples 1 to 3 and 8 to 10 in which the barrier layer does not contain the polyester (A), it was found that the delamination height is low and the interlayer adhesion is poor. In addition, in Comparative Examples 4 and 5 in which the inner layer and the outer layer do not contain the polyamide (B), the barrier property is low, and the interlayer peeling height is low, so the interlayer adhesion is also low. Further, in Comparative Example 6 having no barrier layer, the barrier property is extremely low, and in Comparative Examples 7 and 11 in which the inner layer and the outer layer consist only of polyester (A) and the barrier layer consists only of polyamide (B) The height is extremely low.

  The multilayer structure of the present invention has high gas barrier properties, is less likely to delaminate on falling or impact from the outside, is easy to handle, and can stably store the contents; It is suitably used as a container for packaging substances that dislike oxygen such as food, cosmetics and medicines, or a preform thereof.

1 inner layer 2, 2A, 2B barrier layer 3 outer layer 4 middle layer

Claims (9)

A multilayer structure comprising at least in part a multilayer structure comprising an inner layer, an outer layer, and at least one barrier layer located between the inner layer and the outer layer,
94 to 99.9 mass% of a polyester (A) in which the inner layer and the outer layer each independently contain a dicarboxylic acid unit containing 80 mol% or more of terephthalic acid units and a diol unit containing 80 mol% or more of ethylene glycol units, A resin composition (C) containing 0.1 to 6% by mass of a polyamide (B) containing a diamine unit containing 70 mol% or more of a metaxylylene diamine unit and a dicarboxylic acid unit,
Polyester (A) 15 to 40 mass% in which the barrier layer contains a dicarboxylic acid unit containing 80 mol% or more of terephthalic acid units and a diol unit containing 80 mol% or more of ethylene glycol units, and 70 metaxylylene diamine units The multilayer structure which consists of a resin composition (D) containing 60-85 mass% of polyamide (B) containing the diamine unit and the dicarboxylic acid unit which contain mol% or more.   The multilayer structure according to claim 1, wherein the polyamide (B) is a polyamide comprising a diamine unit containing 70 mol% or more of metaxylylene diamine unit and a dicarboxylic acid unit containing 70 mol% or more of adipic acid unit.   A polyamide (B) is a polyamide comprising a diamine unit containing 70 mol% or more of metaxylylene diamine unit, and a dicarboxylic acid unit containing 70 to 99 mol% of adipic acid unit and 1 to 30 mol% of isophthalic acid unit The multilayer structure according to claim 1 or 2.   Polyester (A) is a dicarboxylic acid unit containing 80 to 99.9 mol% of terephthalic acid unit and 0.1 to 10 mol% of metal sulfoisophthalic acid unit, and a diol unit containing 80 mol% or more of ethylene glycol unit The multilayer structure according to any one of claims 1 to 3, which is a polyester comprising.   The multilayer structure according to any one of claims 1 to 4, which has at least a three-layer structure consisting of an inner layer / barrier layer / outer layer. At least in part a five-layer structure consisting of an inner layer / barrier layer / intermediate layer / barrier layer / outer layer,
Polyester (A) 94 to 99.9 mass% in which the intermediate layer contains a dicarboxylic acid unit containing 80 mol% or more of terephthalic acid units and a diol unit containing 80 mol% or more of ethylene glycol units, and metaxylylene diamine unit The resin composition (E) according to any one of claims 1 to 4, which comprises a resin composition (E) containing 0.1 to 6% by mass of a polyamide (B) containing a diamine unit containing 70 mol% or more and a dicarboxylic acid unit. Multi-layered structure.   The multilayer structure according to any one of claims 1 to 6, which is a preform.   The multilayer structure according to any one of claims 1 to 6, which is a container obtained by blow molding a preform by a hot parison method or a cold parison method.   The multilayer structure according to claim 7 or 8, which has a multilayer structure at least in the body portion.

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