JP4821353B2 - Multilayer bottle - Google Patents

Description

  The present invention relates to prevention of delamination of multilayer bottles having excellent gas barrier properties. Specifically, the multilayer bottle is filled with contents by improving interlayer adhesion between the innermost layer and the outermost layer and the intermediate layer. The multilayer bottle is prevented from delamination when the multilayer bottle is transported or subjected to an impact when dropped, and it is possible to avoid delamination without having a shape with few uneven parts and bent parts. It relates to a multilayer bottle with a high degree.

  Currently, plastic containers (such as bottles) mainly composed of polyester such as polyethylene terephthalate (PET) are widely used for tea, fruit juice drinks, carbonated drinks and the like. The proportion of small plastic bottles in plastic containers is increasing year by year. Since the ratio of the surface area per unit volume increases as the bottle becomes smaller, the shelf life of the contents tends to be shorter when the bottle is made smaller. In recent years, plastic bottles of beer that are easily affected by oxygen and light and hot sale of plastic bottled tea have been sold, and the use of plastic containers has expanded, and gas barriers against oxygen and carbon dioxide for plastic containers have expanded. There is a demand for further improvement in performance.

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

  As an example of a multilayer bottle, a mold cavity is formed by injecting a thermoplastic polyester resin such as PET, which forms the innermost layer and the outermost layer, and a thermoplastic gas barrier resin such as polymetaxylylene adipamide (polyamide MXD6). A bottle in which a preform (parison) having a three-layer or five-layer structure obtained by filling is biaxially stretch blow molded has been put into practical use.

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

  The said multilayer bottle is utilized for containers, such as beer, tea, and a carbonated drink, from the favorable gas barrier property. Multi-layer bottles are used in these applications to maintain the quality of contents and improve shelf life, while delamination occurs between different resins, for example, the innermost layer and the outermost and intermediate layers. There is a problem that damages value.

As a method of improving such problems, the polyamide MXD6 is blended with nylon 6 and nylon 6I / 6T to suppress the crystallization of the barrier layer, and the crystallization speed is slow or the polyamide is not crystallized. Therefore, it has been disclosed to improve delamination (see Patent Document 1). However, according to this method, in order to suppress the crystallization of polyamide MXD6 and to slow down the crystallization speed, it is necessary to add a considerable amount of nylon 6 and nylon 6I / 6T, which have relatively poor gas barrier properties with respect to polyamide MXD6. . Therefore, the gas barrier property is inferior to the multilayer bottle using only polyamide MXD6, and the shelf life cannot be sufficiently improved. In addition, when a transition metal catalyst is mixed for the purpose of providing an oxygen absorption function to compensate for the lowered oxygen barrier property, there is a problem that the cost for addition increases, and even if a transition metal catalyst is added, carbon dioxide is added. Since the barrier property is not improved, it has a problem that it is not suitable for containers such as beer and carbonated drinks. In addition, according to the disclosed method, these polyamides need to be melt-blended by an extruder prior to bottle molding, which has a problem in that the cost for production increases.
US Patent Application Publication No. 2005/0009976

  The object of the present invention is to solve the above-mentioned problems, and in a multi-layer bottle, peeling due to dropping or impact is unlikely to occur, and it is not necessary to have a shape with few uneven parts and bent parts to prevent peeling, and the design flexibility is The object is to provide a large, multi-layer bottle excellent in gas barrier production at low cost.

  As a result of intensive studies on the delamination resistance of the multilayer bottle, the present inventors have made the barrier layer to have a specific composition, thereby making the barrier layer flexible and improving the adhesion between the layers. The inventors have found that peeling can be prevented and have arrived at the present invention.

  That is, the present invention is a multilayer bottle comprising an outermost layer and an innermost layer, and at least one barrier layer located between the outermost layer and the innermost layer, wherein the outermost layer and the innermost layer contain 80 moles of terephthalic acid. % Of a dicarboxylic acid component containing at least 80% and a diol component containing at least 80 mol% of ethylene glycol, and the barrier layer is made up of 70 mol of metaxylylenediamine with a barrier layer of polyester (A). % Of the diamine component and a polyamide (B) obtained by polycondensation of a dicarboxylic acid component containing 70 mol% or more of an α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms, 23 ° C., 50 % RH, comprising a blend of at least two components of polyamide (C) having a water absorption rate at 1 atm higher than that of polyamide (B), and The present invention relates to a multilayer bottle characterized in that the weight of polyamide (C) is 20% by weight or less based on the weight of the barrier layer.

  According to the present invention, since delamination hardly occurs, the degree of freedom of the container shape can be increased, and a multilayer bottle excellent in gas barrier properties can be obtained at a low cost. Therefore, the industrial significance of the present invention is great. .

The thermoplastic polyester resin that may form the outermost layer, the innermost layer, and in some cases the intermediate layer of the multilayer bottle of the present invention comprises a dicarboxylic acid component in which 80 mol% or more, preferably 90 mol% or more is terephthalic acid. 80% by mole or more, preferably 90% by mole or more, a polyester resin obtained by polymerizing a diol component that is ethylene glycol (hereinafter abbreviated as “polyester (A)”).

  As the polyester (A), polyethylene terephthalate is preferably used. It becomes possible to exhibit excellent properties in all of transparency, mechanical strength, injection moldability, and stretch blow moldability of polyethylene terephthalate.

  As other dicarboxylic acid components other than terephthalic acid, isophthalic acid, diphenyl ether-4,4-dicarboxylic acid, naphthalene-1,4 or 2,6-dicarboxylic acid, adipic acid, sebacic acid, decane-1,10-carboxyl Acid, hexahydroterephthalic acid can be used. As other diol components other than ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, diethylene glycol, cyclohexanedimethanol, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis ( 4-hydroxyethoxyphenyl) propane or the like can be used. Furthermore, oxyacids, such as p-oxybenzoic acid, can also be used as a raw material monomer of polyester (A).

  The intrinsic viscosity of the polyester (A) is 0.55 to 1.30, preferably 0.65 to 1.20. When the intrinsic viscosity is 0.55 or more, the multilayer preform can be obtained in a transparent amorphous state, and the mechanical strength of the resulting multilayer bottle is also satisfied. When the intrinsic viscosity is 1.30 or less, bottle molding is easy without impairing fluidity during molding.

  The outermost layer or the innermost layer is mainly composed of the polyester (A), but may be used by blending the polyester (A) with other thermoplastic resins and various additives within a range not impairing the characteristics of the present invention. it can. At that time, 90% by weight or more of the outermost layer or the innermost layer is preferably the polyester (A). Examples of the thermoplastic resin include thermoplastic polyester resins such as polyethylene-2,6-naphthalenedicarboxylate, polyolefin resins, polycarbonate, polyacrylonitrile, polyvinyl chloride, polystyrene, and the like. Examples of the additive include an ultraviolet absorber, an oxygen absorber, a colorant, and an infrared absorber (reheat additive) for accelerating the heating of the preform and shortening the cycle time during molding.

The barrier layer of the multilayer bottle of the present invention has an oxygen transmission coefficient (OTR) of OTR (average value) ≦ 0.15 cc · mm / (m ² · day · atm) under the conditions of a temperature of 23 ° C. and a relative humidity of 60% RH. It is preferable to satisfy. The OTR is more preferably OTR ≦ 0.12 cc · mm / (m ² · day · atm), more preferably OTR ≦ 0.10 cc · mm / (m ² · day · atm), and particularly preferably OTR ≦ 0. 0.08 cc · mm / (m ² · day · atm) is satisfied. By using such a barrier layer exhibiting OTR performance, the gas barrier performance of the resulting bottle is improved, and the expiration date of the contents to be stored can be extended.

The barrier layer of the multilayer bottle of the present invention is composed of a diamine component containing 70 mol% or more of metaxylylenediamine, 100 to 70 mol% of an α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms, and an aromatic dicarboxylic acid. Polyamide (B) obtained by polycondensation with a dicarboxylic acid component containing 0 to 30 mol% of acid, and the water absorption rate at 23 ° C., 50% RH, 1 atm is higher than the saturated water content of polyamide (B) It is preferable to consist of the blend which consists of a polyamide (C) at least 2 component.

In general, polyamide has water absorption, and the water absorption speed varies depending on the type of polyamide. In addition, various physical properties of polyamide change due to water absorption, for example, it becomes flexible. The polyamide (B) also becomes flexible when it absorbs water, and when it is used as a barrier layer of a multilayer bottle, the higher the water absorption, the better the delamination resistance.
However, since the polyamide (B) has a lower water absorption rate than other polyamides, when it is used as a barrier layer of a multilayer bottle, the water absorption rate is not sufficient and the delamination resistance may be inferior. .
On the other hand, if polyamide MXD6 having a high moisture content is used during bottle molding in order to increase the amount of water absorption in the multilayer bottle of polyamide (B), moisture is evaporated and foamed by heat applied during molding, and the product does not become a product. There was a problem. Usually, in order to suppress foaming during molding, the polyamide (B) is used after being dried to about several hundred ppm or less.
Therefore, by blending polyamide (C) having a higher water absorption rate than polyamide (B), the water absorption rate of the barrier layer after bottle molding is increased, the flexibility and adhesion between layers are improved, and the delamination resistance is improved. I found it to be good.

Here, the water absorption rate of the polyamide (B) or the polyamide (C) is 23 ° C., 50% RH, 1 atm, and can be measured by the following method.
(1) Pre-dried pellets are stored for 24 hours under conditions of 23 ° C., 50% RH, 1 atm.
The moisture content of the (2) Save longitudinal pellets, by Karl Fischer method, 235 ° C., measured at 30 minutes of conditions, from the water content after water absorption, reduce the water content prior to water absorption, at (time) ^1/2 The value obtained by dividing was taken as the water absorption rate.
The reason for dividing by (time) ^1/2 is that the water absorption speed immediately after the start of water absorption gradually decreases and changes every moment, so that the influence is averaged and expressed. If you simply divide by time, the value will be different, but the substantial meaning will not change.

23 ° C. of the polyamide (B), 50% RH, preferably water absorption rate is 100 to 500 ppm / hr ^1/2 at 1 atm, and more preferably from 150~400ppm / hr ^1/2.
On the other hand, 23 ° C. of polyamide (C), 50% RH, preferably water absorption rate is 250~1500ppm / hr ^1/2 at 1 atm, more preferably 300~1300ppm / hr ^1/2, and particularly preferably 500 ~ 1200 ppm / hr ^1/2 . When the water absorption rate of the polyamide (C) is within the above range, water is immediately supplied from the polyamide (C) that has immediately absorbed water after blow molding the bottle to the polyamide (B), so that the polyamide (B) becomes flexible and the bottle becomes flexible. Since the followability of the barrier layer to the core layer when an impact is applied to the film becomes good, the effect on delamination resistance is excellent.

The polyamide (B) used in the present invention comprises a diamine component mainly composed of metaxylylenediamine and a dicarboxylic acid component mainly composed of an α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms. It is a polyamide obtained by polycondensation. The polyamide has high barrier performance and exhibits excellent properties in co-injection moldability and co-stretch blow moldability with polyester (A) (mainly polyethylene terephthalate).

  The diamine component in the polyamide (B) contains metaxylylenediamine at 70 mol% or more, preferably 75 mol% or more, more preferably 80 mol% or more. If the amount of metaxylylenediamine in the diamine component is less than 70 mol%, the gas barrier property of the polyamide (B) is lowered, which is not preferable. Examples of diamine components that can be used in addition to metaxylylenediamine in the present invention include tetramethylenediamine, pentamethylenediamine, 2-methylpentanediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, Aliphatic diamines such as dodecamethylenediamine, 2,2,4-trimethyl-hexamethylenediamine, 2,4,4-trimethylhexamethylenediamine, 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (amino) Methyl) cyclohexane, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, bis (4-aminocyclohexyl) methane, 2,2-bis (4-aminocyclohexyl) propane, bis (aminomethyl) de Aliphatic diamines such as phosphorus and bis (aminomethyl) tricyclodecane, diamines having aromatic rings such as bis (4-aminophenyl) ether, paraphenylenediamine, paraxylylenediamine, and bis (aminomethyl) naphthalene However, the present invention is not limited to these examples.

  The dicarboxylic acid component in the polyamide (B) contains an α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms in an amount of 70 mol% or more, preferably 75 mol% or more, more preferably 80 mol% or more. When it is in the above range, the polyamide has excellent barrier properties and moldability. Examples of the α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms used in the present invention include succinic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, adipic acid, sebacic acid, undecanedioic acid, Aliphatic dicarboxylic acids such as dodecanedioic acid can be exemplified, but among these, adipic acid is preferred.

In the present invention, as the dicarboxylic acid other than the α, ω-linear aliphatic dicarboxylic acid, aromatic dicarboxylic acids exemplified by terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, etc. It can also be added. Furthermore, a small amount of monoamine or monocarboxylic acid may be added as a molecular weight regulator during the polycondensation of the polyamide.
In the present invention, a dicarboxylic acid component containing 99.5 to 70 mol% of α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms and 0.5 to 30 mol% of aromatic dicarboxylic acid is used. It is preferable.

  The polyamide (B) can be produced by a melt polycondensation method. For example, it is manufactured by a method in which a nylon salt composed of metaxylylenediamine and adipic acid is heated in the presence of water in a pressurized state and polymerized in a molten state while removing added water and condensed water. Further, it is also produced by a method in which metaxylylenediamine is directly added to molten adipic acid and polycondensed under normal pressure. In this case, in order to keep the reaction system in a uniform liquid state, metaxylylenediamine is continuously added to adipic acid, and during this time, the reaction system is raised so that the reaction temperature does not fall below the melting point of the generated oligoamide and polyamide. The polycondensation proceeds while warming.

  Polyamide (B) may be subjected to polycondensation by solid-phase polymerization after being produced by a melt polymerization method. The method for producing the polyamide is not particularly limited, and it is produced by a conventionally known method and polymerization conditions.

The number average molecular weight of the polyamide (B) is preferably 18000 to 43500, more preferably 20000 to 30000. Within this range, molding into a multilayer bottle is good, and the resulting multilayer bottle has excellent delamination resistance. When the number average molecular weight of the polyamide (B) is 18000 to 43500, the relative viscosity of the polyamide (B) is about 2.3 to 4.2, and when it is 20000 to 30000, about 2.44 to 3.500. 19 The relative viscosity here refers to a value obtained by dissolving 1 g of polyamide in 100 ml of 96% sulfuric acid and measuring at 25 ° C. using a Canon Fenceke viscometer or the like.

  A phosphorous compound can be added to the polyamide (B) in order to enhance the processing stability during melt molding or to prevent the polyamide (B) from being colored. As the phosphorus compound, a phosphorus compound containing an alkali metal or an alkaline earth metal is preferably used. For example, an alkali metal or alkaline earth metal phosphate such as sodium, magnesium, calcium, hypophosphite, phosphorus Acid salts may be mentioned, but those using alkali metal or alkaline earth metal hypophosphites are particularly preferred because they are particularly excellent in the anti-coloring effect of polyamide. The density | concentration of a phosphorus compound is 1-500 ppm as a phosphorus atom, Preferably it is 350 ppm or less, More preferably, it is 200 ppm or less. Even if the phosphorus atom concentration exceeds 500 ppm, there is no change in the anti-coloring effect. Rather, the haze of the film obtained using this increases, which is not preferable.

As the polyamide (C), an aliphatic polyamide and / or an amorphous semi-aromatic polyamide is preferably used because of its high water absorption rate. Examples of aliphatic polyamides include poly (6-aminohexanoic acid) (PA-6), also known as poly (caprolactam), poly (hexamethylene adipamide) (PA-6,6), poly (7-aminoheptane) Acid) (PA-7), poly (10-aminodecanoic acid) (PA-10), poly (11-aminoundecanoic acid) (PA-11), poly (hexamethylene sebacamide) (PA-6,10) , Homopolymers such as poly (hexamethylene azelamide) (PA-6,9), poly (tetramethylene adipamide) (PA-4,6), caprolactam / hexamethylene adipamide copolymer (PA-6,6 / Examples thereof include aliphatic polyamides such as 6)) and hexamethylene adipamide / caprolactam copolymer (PA-6 / 6, 6). Among these, PA-6 and PA-6, 6 can be particularly preferably used.

As amorphous semi-aromatic polyamides, poly (hexamethylene isophthalamide) (PA-6I), hexamethylene isophthalamide / hexamethylene terephthalamide copolymer (PA-6I / 6T), poly (metaxylylene isophthalate) Lamid) (PA-MXDI), caprolactam / metaxylylene isophthalamide copolymer (PA-6 / MXDI), caprolactam / hexamethylene isophthalamide copolymer (PA-6 / 6I), and the like. Among these, PA-6I / 6T can be particularly preferably used.

Polyamide (C) can be used by blending one or more resins. When only an aliphatic polyamide is added to the polyamide (B), the crystallization speed is increased depending on the type and amount of addition, which may cause inconvenience when the bottle is molded. In addition, when only an amorphous semi-aromatic polyamide is added to the polyamide (B), the crystallization speed may be slowed depending on the type and amount of addition, which may cause inconvenience when the bottle is molded. Therefore, it is often preferred to simultaneously use an aliphatic polyamide and an amorphous semi-aromatic polyamide as the polyamide (C).

The blending method of polyamide (B) and polyamide (C) is not particularly limited, and may be supplied by dry blending when a bottle preform is produced. A single screw extruder or a twin screw extruder prior to preform production. It is possible to use a melt-blend by making a masterbatch by melt-blending, but a simple melt-blend is costly to compound, so dry-blend or melt-blend to supply cheaply It is preferable to create a master batch by

In the present invention, the weight of the polyamide (C) is preferably 1 to 20% by weight, more preferably 1.5 to 15% by weight, still more preferably 2 to 10% by weight based on the weight of the barrier layer. is there. Within this range, molding into a multilayer bottle is good, and the resulting multilayer bottle has excellent delamination resistance and good barrier properties.

The barrier layer is preferably mainly composed of polyamide (B). From the viewpoint of barrier performance, the polyamide (B) is more preferably contained in an amount of 70% by weight or more, and more preferably 80% by weight or more. Especially preferably, it is 90 weight% or more. It is. Depending on the type of resin or the like added to the polyamide (B), if they are contained in an amount exceeding 30% by weight, the above-mentioned OTR exceeds 0.15 cc · mm / (m ² · day · atm), and the barrier performance is increased. Be careful as it can be damaged.

In the present invention, the polyamide (C) is preferably a combination of 1 to 10% by weight of aliphatic polyamide and 1 to 10% by weight of amorphous semi-aromatic polyamide based on the weight of the barrier layer. 10% by weight aliphatic polyamide and 1-5% by weight amorphous semi-aromatic polyamide, or 1-5% by weight aliphatic polyamide and 1-10% by weight amorphous semi-aromatic polyamide More preferably, it is polyamide. Particularly preferred are 1 to 10% by weight of aliphatic polyamide and 2 to 4% by weight of amorphous semi-aromatic polyamide. When the content is in the above range, bottles can be easily molded, and a bottle with improved delamination resistance can be obtained without substantially lowering barrier properties.

In addition, the barrier layer may be blended with one or more other resins such as polyester, olefin, phenoxy resin and the like within a range that does not impair the purpose. In addition, inorganic fillers such as glass fibers and carbon fibers; plate-like inorganic fillers such as glass flakes, talc, kaolin, mica, montmorillonite, and organized clay; impact modifiers such as various elastomers; crystal nucleating agents ; Lubricants such as fatty acid amides, fatty acid metal salts, fatty acid amides; copper compounds, organic or inorganic halogen compounds, hindered phenols, hindered amines, hydrazines, sulfur compounds, phosphorus compounds, etc. Agents: Thermal stabilizers, anti-coloring agents, UV absorbers such as benzotriazoles, release agents, plasticizers, coloring agents, flame retardants and other additives, compounds containing cobalt metal which is a compound that imparts oxygen scavenging ability Further, additives such as alkali compounds for the purpose of preventing gelation of polyamide can be added.

  In the multilayer bottle of the present invention, a portion having a low draw ratio (1 to 2.5 times) may occur depending on the shape of the preform and the bottle. When the barrier layer of the low draw ratio part absorbs water, it may whiten, but when polyamide (C) having a higher water absorption rate than polyamide (B) is added, water absorption is promoted. Therefore, by adding an anti-whitening agent to the barrier layer as necessary, whitening is suppressed and a multilayer bottle with good transparency can be obtained.

  The whitening inhibitor used in the present invention is a fatty acid metal salt having 18 to 50 carbon atoms, preferably 18 to 34 carbon atoms. With 18 or more carbon atoms, whitening prevention can be expected. Further, when the number of carbon atoms is 50 or less, uniform dispersion in the barrier layer is good. Fatty acids may have side chains and double bonds, but linear saturated such as stearic acid (C18), eicosanoic acid (C20), behenic acid (C22), montanic acid (C28), triacontanoic acid (C30) Fatty acids are preferred. The metal that forms a salt with the fatty acid is not particularly limited, but sodium, potassium, lithium, calcium, barium, magnesium, strontium, aluminum, zinc, etc. are exemplified, and sodium, potassium, lithium, calcium, aluminum, and zinc are particularly preferable.

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

  The addition amount of the fatty acid metal salt is preferably 0.005 to 1.0 part by weight, more preferably 0.05 to 0.5 part by weight, particularly preferably 0.12 with respect to 100 parts by weight of the total amount of the barrier layer. -0.5 parts by weight. Addition of 0.005 part by weight or more with respect to 100 parts by weight of the total amount can be expected to prevent whitening. Moreover, it becomes possible to keep the cloudiness of the multilayer bottle obtained that the addition amount is 1.0 part by weight or less with respect to the total amount of 100 parts by weight.

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

  The diamide compound is obtained from a fatty acid having 8 to 30 carbon atoms and a diamine having 2 to 10 carbon atoms. When the fatty acid has 8 or more carbon atoms and the diamine has 2 or more carbon atoms, an effect of preventing whitening can be expected. Further, when the fatty acid has 30 or less carbon atoms and the diamine has 10 or less carbon atoms, uniform dispersion is good. The fatty acid may have a side chain or a double bond, but a linear saturated fatty acid is preferred.

  Examples of the fatty acid component of the diamide compound include stearic acid (C18), eicosanoic acid (C20), behenic acid (C22), montanic acid (C28), and triacontanoic acid (C30). Examples of the diamine component of the diamide compound include ethylenediamine, butylenediamine, hexanediamine, xylylenediamine, and bis (aminomethyl) cyclohexane. A diamide compound obtained by combining these is used in the present invention. A diamide compound obtained from a diamine composed mainly of a fatty acid having 8 to 30 carbon atoms and mainly ethylenediamine, or a diamide compound obtained from a fatty acid mainly composed of montanic acid and a diamine having 2 to 10 carbon atoms is preferred.

  The diester compound is obtained from a fatty acid having 8 to 30 carbon atoms and a diol having 2 to 10 carbon atoms. When the fatty acid has 8 or more carbon atoms and the diol has 2 or more carbon atoms, an effect of preventing whitening can be expected. Further, when the fatty acid has 30 or less carbon atoms and the diol has 10 or less carbon atoms, uniform dispersion in the mixed resin B is good. The fatty acid may have a side chain or a double bond, but a linear saturated fatty acid is preferred.

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

  The addition amount of the diamide compound and / or diester compound is preferably 0.005 to 1.0 part by weight, more preferably 0.05 to 0.5 part by weight, particularly preferably 100 parts by weight of the total amount of the barrier layer. Is 0.12 to 0.5 parts by weight. Addition of 0.005 part by weight or more with respect to 100 parts by weight of the total amount can be expected to prevent whitening. Further, when the addition amount is 1.0 part by weight or less with respect to the total amount of 100 parts by weight, it becomes possible to keep the haze value of the resulting multilayer bottle low.

  A conventionally known mixing method can be applied to the addition of the whitening inhibitor to the polyamide (barrier layer). For example, a polyamide resin pellet, a metal catalyst compound, and a whitening inhibitor may be charged into a rotating hollow container and mixed for use. Further, after producing a polyamide resin composition containing a high concentration of whitening inhibitor, it is diluted with a polyamide resin pellet containing no whitening agent at a predetermined concentration, and this is melt kneaded, continuously after melt mixing. A method of molding by injection molding or the like is employed.

  When the whitening inhibitor is used, it is possible to prevent the barrier layer from being whitened immediately after the production of the multilayer bottle. Further, it is possible to prevent the barrier layer from being whitened after the multilayer bottle is stored for a long time under the condition that the whitening does not occur or the whitening does not increase. That is, even if a whitening inhibitor is not added, it does not whiten or does not increase in whitening, for example, after long-term storage in an atmosphere at a temperature of 23 ° C. and a humidity of 50% RH, the multilayer bottle is exposed to high humidity, water or boiling water. Even if it is brought into contact with the glass or heated to a temperature higher than the glass transition temperature, whitening is suppressed as in the case immediately after molding.

In the present invention, 1 to 1000 ppm of an antistatic agent can be added to a blend composed of polyamide (B) and polyamide (C). When polyamide (B) and polyamide (C) are dry blended, their dielectric constants are different, so depending on the usage environment, when polyamide (B) and polyamide (C) are separated and classified by static electricity, they are molded. The blending ratio may vary, and a predetermined performance may not be obtained for the molded bottle. Therefore, if necessary, an antistatic agent is added to the barrier layer so that the polyamide (B) and the polyamide (C) are properly blended, and a multilayer bottle with good performance can be obtained.

  As the antistatic agent used in the present invention, known substances such as nonionic surfactants, anionic (anionic) surfactants, and cationic (cationic) surfactants can be used. Nonionic surfactants include ester type, ether type, alkylphenol type polyethylene glycol surfactants, sorbitan ester type polyhydric alcohol partial ester type surfactants, polyoxyethylene sorbitan ester type ester ether type surfactants. However, it is not limited to these. In the present invention, polyoxyethylene sorbitan monolaurate, which is a kind of polyoxyethylene sorbitan ester type ester ether surfactant, is preferable because it has an excellent antistatic effect on polyamide (B) and polyamide (C). Used.

  One type of antistatic agent may be used, or two or more types may be used in combination. The addition amount of the antistatic agent is preferably 1 to 1000 ppm, more preferably 10 to 500 ppm, and particularly preferably 20 to 100 ppm with respect to the total amount of the barrier layer. Within this range, the blending ratio of the polyamide is stable, and a stable quality bottle can be produced.

The multilayer bottle of the present invention uses an injection molding machine having two injection cylinders to mold a blend of polyester (A), polyamide (B) and polyamide (C) from the injection cylinders on the skin side and the core side, respectively. A multilayer preform obtained by injection into a mold cavity through a hot runner is obtained by further biaxially stretching blow molding by a known method.

In general, blow molding of a multilayer preform includes conventionally known methods such as a so-called cold parison method and a hot parison method. For example, the surface of the multilayer preform is stretched in the axial direction by mechanical means such as heating to 80 to 120 ° C. and then pressing with a core rod insert, and then normally 2 to 4 MPa of high pressure air is blown and stretched in the transverse direction. For example, a method of molding, a method of crystallizing the mouth portion of the multilayer preform, heating the surface to 80 to 120 ° C., and then blow-molding in a mold of 90 to 150 ° C.

In the present invention, the preform heating temperature is preferably 90 to 110 ° C, more preferably 95 to 108 ° C. When the preform heating temperature is lower than 90 ° C., the heating becomes insufficient, and the barrier layer or the PET layer may be cold-stretched and whitened. A temperature higher than 110 ° C. is not preferable because the barrier layer crystallizes and whitens. In addition, the delamination resistance may decrease.

In the present invention, since the barrier property, moldability, etc. are excellent, the multilayer bottle has a three-layer structure of polyester (A) layer / barrier layer / polyester (A) layer, or polyester (A) layer / barrier layer / polyester ( It is preferable to have a five-layer structure of A) layer / barrier layer / polyester (A) layer.

A multilayer bottle having a three-layer structure or a five-layer structure can be obtained by further biaxially stretching blow-molding a multilayer preform having a three-layer structure or a five-layer structure by a known method. There is no particular limitation on the method for producing a multilayer preform having a three-layer structure or a five-layer structure, and a known method can be used. For example, in the step of injecting the polyester (A) constituting the innermost layer and the outermost layer from the skin side injection cylinder, and injecting the resin constituting the barrier layer from the core side injection cylinder, the polyester (A) is injected first, and then Three-layer structure (polyester (A) layer / barrier layer / polyester) by simultaneously injecting the resin constituting the barrier layer and polyester (A) and then injecting the required amount of polyester (A) to fill the mold cavity A multilayer preform (A) can be produced.

Further, in the step of injecting the polyester (A) constituting the innermost layer and the outermost layer from the skin side injection cylinder, and injecting the resin constituting the barrier layer from the core side injection cylinder, first the polyester A is injected, and then the barrier is removed. By injecting the constituent resin alone and finally injecting the polyester (A) to fill the mold cavity, a five-layer structure (polyester (A) layer / barrier layer / polyester (A) layer / barrier layer / A multilayer preform of polyester (A) layer can be produced.
The method for producing the multilayer preform is not limited to the above method.

  The thickness of the polyester (A) layer in the multilayer bottle is preferably 0.01 to 1.0 mm, and the thickness of the barrier layer is preferably 0.005 to 0.2 mm (5 to 200 μm). . Moreover, the thickness of a multilayer bottle does not need to be constant throughout the bottle, and is usually in the range of 0.2 to 1.0 mm.

  In a multi-layer bottle obtained by biaxial stretching blow molding of a multi-layer preform, gas barrier performance can be exhibited if at least the barrier layer is present in the body of the multi-layer bottle, but the barrier layer extends to the vicinity of the top end of the multi-wall bottle stopper. The gas barrier performance is even better when the is extended.

  In the multilayer bottle of the present invention, the weight of the barrier layer is preferably 1 to 20% by weight, more preferably 2 to 15% by weight, and particularly preferably 3 to 10% by weight based on the total weight of the multilayer bottle. By setting the weight of the barrier layer in the above range, a multilayer bottle having good gas barrier properties can be obtained, and molding from a precursor, which is a precursor, into a multilayer bottle is facilitated.

In the present invention, when producing a multilayer preform in producing a multilayer bottle, a method in which a mixture obtained by dry blending polyamide (B) and polyamide (C) is supplied to a molding machine is particularly preferred. By supplying by dry blending, the cost for melt blending can be suppressed and a bottle with excellent competitiveness can be obtained. Also, depending on the conditions when melt blending, an excessive heat history is added to the polyamide (B) or polyamide (C), the polyamide deteriorates and the conditions become unstable when the preform is produced, or the polyamide turns yellow This is because the color may change. Moreover, when dry blending polyamide (B) and polyamide (C), it is preferable to add an antistatic agent.

When the polyamide (B) and the polyamide (C) are mixed by melt blending, the polyamide (B) and / or the polyamide (C) is used for improving processing stability during melt molding, In order to prevent coloring, it is preferable to add a phosphorus compound. As the phosphorus compound, a phosphorus compound containing an alkali metal or an alkaline earth metal is preferably used. For example, an alkali metal or alkaline earth metal phosphate such as sodium, magnesium, calcium, hypophosphite, phosphorus Acid salts may be mentioned, but those using alkali metal or alkaline earth metal hypophosphites are particularly preferred because they are particularly excellent in the anti-coloring effect of polyamide. The density | concentration of a phosphorus compound is 1-500 ppm as a phosphorus atom, Preferably it is 350 ppm or less, More preferably, it is 200 ppm or less.

  In the multilayer bottle of the present invention, delamination due to dropping or impact does not easily occur, and the barrier performance is not sacrificed as in the conventional invention. Further, even when the shape includes an uneven portion and a bent portion, delamination is unlikely to occur. Therefore, the shape of the multilayer bottle is not limited to a shape having few uneven portions and a bent portion, and the degree of freedom in design is increased. The multi-layer bottles of the present invention are, for example, carbonated drinks, juices, water, milk, sake, whiskey, shochu, coffee, tea, jelly drinks, health drinks and other liquid drinks, seasonings, sauces, soy sauce, dressings, liquid soup It is suitable for storage and storage of various articles such as liquid seasonings, liquid foods such as liquid soup, liquid pharmaceuticals, skin lotions, cosmetic emulsions, hair conditioners, hair dyes, shampoos and the like.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. In addition, evaluation of the multilayer bottle was performed by the following method.
(1) Delamination Height Based on ASTM D2463-Procedure B, the delamination height was determined by a container drop test and evaluated. The higher the delamination height, the better the delamination resistance. First, the multilayer container was filled with water and capped, and then the multilayer container was dropped to visually determine the presence or absence of delamination. The multilayer container was dropped vertically so that the bottom part was in contact with the floor. The drop height interval is 15 cm. There are 30 test bottles.
(2) Oxygen permeability / oxygen permeability coefficient The bottle was measured for oxygen permeability in accordance with ASTM D3985 in an atmosphere of 23 ° C., 100% RH inside the bottle, and 50% outside the bottle. The measurement used Modern Controls make and OX-TRAN 2/61. The lower the value, the better the oxygen barrier property.
Further, the oxygen permeability coefficient (OTR) of the bottle barrier layer was measured under the conditions of 60% RH and 23 ° C. by carefully disassembling the bottle and taking out only the barrier layer. For the measurement, OX-TRAN 2/61 manufactured by Modern Controls was used.
(3) Carbon dioxide barrier (CO2 Loss)
4G. V. Carbonated water was filled so that the pressure would be 5 ° C. and stored in an atmosphere of 23 ° C. and 50% RH, and the temporal change in the bottle internal pressure was continuously measured. Since the carbon dioxide inside the bottle permeates from the bottle wall surface with time, the pressure decreases with time. The initial pressure was 100%, and the period until the pressure decreased to 90% was regarded as the shelf life, and the carbon dioxide barrier property of the bottle was evaluated. Larger values indicate better carbon dioxide barrier properties.
(4) Water absorption rate Pre-dried polyamide was stored for 1 day under the conditions of 23 ° C., 50% RH, 1 atm, and the moisture content before and after water absorption was determined by the Karl Fischer method using AQ-2000 manufactured by Hiranuma Sangyo Co., Ltd. The measurement temperature was 235 ° C., and the measurement time was 30 minutes. The value obtained by subtracting the water content before water absorption from the water content after water absorption and dividing by (time) ^1/2 was defined as the water absorption rate. The reason for dividing by (time) ^1/2 is that the water absorption speed immediately after the start of water absorption gradually decreases and changes every moment, so that the influence is averaged and expressed. If you simply divide by time, the value will be different, but the substantial meaning will not change.

< Reference Example 1 >
Under the following conditions, a three-layer preform (27 g) composed of a polyester (A) layer / barrier layer / polyester (A) layer is injection molded, and after cooling, the preform is heated and biaxial stretch blow molding is performed. Got a bottle. As the resin constituting the polyester (A) layer, a polyethylene terephthalate having an intrinsic viscosity (a mixed solvent of phenol / tetrachloroethane = 6/4 (weight ratio), measuring temperature 30 ° C.) of 0.75 (Japan) As the resin (barrier resin) constituting the barrier layer using RTpet C (Unipet), 95% by weight of polymetaxylylene adipamide (MX Nylon S6007 manufactured by Mitsubishi Gas Chemical Co., Ltd.) and nylon 6 (Ube Industries, Ltd.) 1015B) 5% by weight of mixed resin was used. In addition, when the resin was mixed, 50 ppm of polyoxyethylene sorbitan monolaurate (Nonion LT-221, manufactured by NOF Corporation) was added as an antistatic agent, and dry blended for 30 minutes with a tumbler. Stable quality preforms were obtained without classification of the pellets or adhesion of the pellets to the hopper wall due to static electricity during preform molding. The weight of the barrier layer with respect to the total weight of the obtained multilayer bottle was 5% by weight. The evaluation results of the multilayer bottle are shown in Table 1.

(Three-layer preform shape)
Total length 95mm, outer diameter 22mm, wall thickness 4.2mm. For the production of the three-layer preform, an injection molding machine (model: M200, 4 pieces) manufactured by Meiki Seisakusho Co., Ltd. was used.
(Three-layer preform molding conditions)
Skin side injection cylinder temperature: 280 ℃
Core side injection cylinder temperature: 250 ° C
Resin channel temperature in mold: 280 ° C
Mold cooling water temperature: 15 ° C
Ratio of barrier resin in preform: 5% by weight
(Multilayer bottle shape)
Total length 223mm, outer diameter 65mm, inner volume 500ml, bottom shape is champagne type, body has no dimples. The biaxial stretch blow molding used a blow molding machine (model: EFB1000ET) manufactured by Frontier.
(Biaxial stretch blow molding conditions)
Preform heating temperature: 103 ° C
Stretching rod pressure: 0.5 MPa
Primary blow pressure: 1.0 MPa
Secondary blow pressure: 2.5 MPa
Primary blow delay time: 0.35 sec
Primary blow time: 0.28 sec
Secondary blow time: 2.0 sec
Blow exhaust time: 0.6 sec
Mold temperature: 30 ℃

<Example 3-5, Reference Example 2, Comparative Examples 1-3>
A multilayer bottle was obtained in the same manner as in Reference Example 1 except that the barrier layer composition was changed to that shown in Table 1. The evaluation results of the multilayer bottle are shown in Table 1.

The resin name abbreviations listed in Table 1 are as follows.
(1) S6007: polymetaxylylene adipamide (manufactured by Mitsubishi Gas Chemical Co., Inc., MX nylon S6007 solid phase polymerized product, number average molecular weight: 23500, relative viscosity (resin 1 g / 96% sulfuric acid 100 ml, measuring temperature 25 ° C.): 2 70, water absorption rate: 280 ppm / h ^1/2 )
(2) S6121: Polymetaxylylene adipamide (Mitsubishi Gas Chemical Co., Ltd. MX nylon S6121 solid phase polymerized product, number average molecular weight: 40000, relative viscosity (resin 1 g / 96% sulfuric acid 100 ml, measurement temperature 25 ° C.): 3 .94, water absorption rate: 270 ppm / h ^1/2 )
(3) 1015B: nylon 6 (manufactured by Ube Industries, Ltd. Grade: 1015B, number average molecular weight: 15000, water absorption rate: 1090 ppm / h ^1/2 )
(4) 1020B: Nylon 6 (Ube Industries, Ltd. grade: 1020B, number average molecular weight: 20000, water absorption rate: 1070 ppm / h ^1/2 )
(4) 2020B: nylon 66 (manufactured by Ube Industries, Ltd. Grade: 2020B, number average molecular weight: 20000, water absorption rate: 1000 ppm / h ^1/2 )
(5) X21F07: Nylon 6I / 6T (Mitsubishi Engineering Plastics grade: Novamid X21F07, water absorption rate: 910 ppm / h ^1/2 )
(6) 3024: Nylon 12 (Ube Industries, Ltd. grade: 3024NUX, saturated moisture content: water absorption rate: 100 ppm / h ^1/2 )

As shown in the above examples, a bottle made of a resin whose barrier layer satisfies a specific water absorption rate, which is a constituent of the present invention, has both excellent delamination resistance and good gas barrier properties. On the other hand, a bottle that does not satisfy a specific condition was inferior in delamination resistance or gas barrier.

Claims (8)

A multi-layer bottle comprising an outermost layer and an innermost layer, and at least one barrier layer located between the outermost layer and the innermost layer, wherein the outermost layer and the innermost layer comprise dicarboxylic acid containing 80 mol% or more of terephthalic acid A diamine component mainly composed of a thermoplastic polyester resin (polyester (A)) obtained by polymerizing a component and a diol component containing 80 mol% or more of ethylene glycol, and the barrier layer containing 70 mol% or more of metaxylylenediamine And a polyamide (B) obtained by polycondensation of a dicarboxylic acid component containing 70 mol% or more of an α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms, at 23 ° C., 50% RH, 1 atm. A blend of at least two components with polyamide (C) having a higher water absorption rate than polyamide (B), and polyamide Weight of (C) is state, and are 20 wt% or less with respect to the barrier layer by weight, the polyamide (C) is, relative to the aliphatic polyamide and the barrier layer weight of from 1 to 10% by weight relative to the barrier layer by weight 1 to 10% by weight of amorphous Shitsuhan aromatic polyamide Tona is,
Multilayer bottle, wherein a water absorption rate of the polyamide (B) is at 100 to 500 ppm / hr ^1/2, absorption rate of the polyamide (C) is 250~1500ppm / hr ^1/2.   The multilayer bottle according to claim 1, wherein the barrier layer contains 0.005 to 1.0 part by weight of a fatty acid metal salt having 18 to 50 carbon atoms with respect to 100 parts by weight of the total amount of the barrier layer.   The multilayer bottle according to claim 1, wherein the barrier layer contains 1 to 1000 ppm of an antistatic agent.   The multilayer bottle according to claim 1, wherein the polyamide (B) has a number average molecular weight of 18000 to 43500.   The multilayer bottle according to claim 1, having a three-layer structure of polyester (A) layer / barrier layer / polyester (A) layer.   The multilayer bottle according to claim 1, which has a five-layer structure of polyester (A) layer / barrier layer / polyester (A) layer / barrier layer / polyester (A) layer.   The multilayer bottle according to claim 1, wherein the weight of the barrier layer is 1 to 20% by weight based on the total weight of the multilayer bottle.   The multilayer bottle according to claim 1, wherein the mixture is formed by supplying a mixture obtained by dry blending polyamide (B) and polyamide (C) to a molding machine.