JP5256615B2 - Multi-layer bottle manufacturing method - Google Patents

Description

  The present invention relates to the prevention of delamination of multilayer bottles having excellent gas barrier properties, and more specifically, the interlayer adhesion between the innermost layer and the outermost layer and the intermediate layer is improved so that the multilayer bottles can be filled and transported. Or a method for preventing delamination due to mechanical and thermal shock when dropped.

  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, beer plastic bottles, which are easily affected by oxygen and light, and hot sale of plastic bottled tea have been sold, and the range of use of plastic containers has expanded, further improving the gas barrier properties of plastic containers. It is requested.

  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 detracts from value.

As a method for improving such a problem, a reverse flow control device capable of causing a fixed amount of reverse flow to the gas barrier layer side when the resin constituting the innermost layer and the outermost layer is finally injected into the mold cavity. Although it has been disclosed to improve the delamination resistance by using a rough mixed resin between layers and making a preform, there is a problem of using a special device (see Patent Document 1). ). In addition, when a multilayer bottle is formed by stretch blow, there is a method in which the primary molded product once blown is heated and shrunk and then blown again at a high pressure. Have a problem that the process is troublesome and the delamination resistance is reduced (see Patent Document 2).
JP 2000-254963 A JP 2001-206336 A

  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 method for producing a large, well-shaped multilayer bottle.

  As a result of earnest research on the delamination resistance and shapeability of the multilayer bottle, the present inventors have improved the adhesion between the layers by blow molding the multilayer preform under a specific condition range, and when dropping. The present inventors have found that the delamination can be prevented and that the shapeability is improved.

That is, the present invention includes an outermost layer and an innermost layer, and at least one barrier layer positioned between the outermost layer and the innermost layer, and the outermost layer and the innermost layer include dicarboxylic acid containing 80 mol% or more of terephthalic acid. A method for producing a multilayer bottle by molding a multilayer preform mainly composed of a thermoplastic polyester resin obtained by polymerizing a component and a diol component containing 80 mol% or more of ethylene glycol. The present invention relates to a method for producing a multilayer bottle, wherein biaxial stretch blow molding is performed by a method that satisfies the conditions of (1) to (4).
(1) After heating the surface of the multilayer preform to 90-110 ° C,
(2) While stretching the multilayer preform longitudinally with a rod in the mold, the pressure is changed in multiple stages and high pressure air is blown.
(3) The first stage pressure (primary blow pressure) when blowing high-pressure air in multiple stages is 0.5 to 2.0 MPa (4) The final stage when blowing high-pressure air in multiple stages The pressure (secondary blow pressure) is 2 to 4 MPa.

  According to the present invention, it is possible to obtain a multi-layer bottle with improved blow moldability, good mold transfer (shaping property), and less delamination. In other words, since delamination can be avoided without having a shape with few uneven parts and bent parts, the degree of freedom of the container shape can be increased and a multilayer bottle excellent in gas barrier properties can be obtained. The industrial significance of the 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 preform used in the present invention is a dicarboxylic acid whose terephthalic acid is 80 mol% or more, preferably 90 mol% or more. It is a polyester resin (hereinafter abbreviated as “polyester (A)”) obtained by polymerizing an acid component and a diol component in which 80 mol% or more, preferably 90 mol% or more is ethylene glycol.

  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.

As the barrier layer, it is preferable to use a material in which the oxygen permeability coefficient (OTR) of the body barrier layer under the conditions of a temperature of 23 ° C. and a relative humidity of 60% RH satisfies the following formula when formed into a bottle.
OTR (average value) ≦ 0.2 cc · mm / (m ² · day · atm)
The OTR is more preferably OTR ≦ 0.15 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.

In this invention, there is no restriction | limiting in particular as a barrier layer material, If it is resin (barrier resin) which satisfy | fills the said OTR conditions, such as various polyamide, ethylene vinyl alcohol copolymer, polyglycolic acid (PGA), it can be used. is there.

As the barrier resin, polycondensation of a diamine component containing 70 mol% or more of metaxylylenediamine and a dicarboxylic acid component containing 50 mol% or more of an α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms. Thus obtained polyamide (B) is preferred.

Polyamide (B) is obtained by polycondensing a diamine component mainly composed of metaxylylenediamine and a dicarboxylic acid component mainly composed of α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms. The resulting polyamide. The polyamide (B) has high barrier performance, exhibits excellent properties in co-injection moldability and co-stretch blow moldability with polyester (A) (mainly polyethylene terephthalate), and has good formability. is there.

  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 50 mol% or more, preferably 70 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 dicarboxylic acids 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, it is preferable to use a dicarboxylic acid component containing 100 to 50 mol% of an α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms and 0 to 50 mol% of an aromatic dicarboxylic acid.

  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 the phosphorus compound in a polyamide (B) 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.

  Other polyamides can be added to the polyamide (B) for the purpose of improving delamination resistance. For example, poly (6-aminohexanoic acid) (PA-6), also known as poly (caprolactam), poly (hexamethylene adipamide) (PA-6,6), poly (7-aminoheptanoic acid) (PA -7), poly (10-aminodecanoic acid) (PA-10), poly (11-aminoundecanoic acid) (PA-11), poly (12-aminododecanoic acid) (PA-12), poly (hexamethylene Homopolymers such as bacamide) (PA-6,10), poly (hexamethylene azelamide) (PA-6,9), poly (tetramethylene adipamide) (PA-4,6), caprolactam / hexamethylene azide Aliphatic polyamides such as amide (PA-6,6 / 6)), hexamethylene adipamide / caprolactam copolymer (PA-6 / 6,6), poly (he Samethylene isophthalamide) (PA-6I), hexamethylene isophthalamide / hexamethylene terephthalamide copolymer (PA-6I / 6T), poly (metaxylylene isophthalamide) (PA-MXDI), caprolactam / meta Amorphous semi-aromatic polyamides such as xylylene isophthalamide copolymer (PA-6 / MXDI) and caprolactam / hexamethylene isophthalamide copolymer (PA-6 / 6I) can be exemplified, but are not limited thereto. .

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 0.2 cc · mm / (m ² · day · atm) and the barrier performance is increased. Be careful as it can be damaged.

  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.

The multilayer bottle manufacturing method of the present invention includes an outermost layer and an innermost layer, and at least one barrier layer positioned between the outermost layer and the innermost layer, and the outermost layer and the innermost layer contain 80 mol% of terephthalic acid. A multilayer preform mainly composed of a thermoplastic polyester resin (polyester (A)) obtained by polymerizing a dicarboxylic acid component containing the above and a diol component containing 80% by mole or more of ethylene glycol has the following (1) to (4) It is preferable to produce a multilayer bottle by biaxial stretch blow molding using a method that satisfies the conditions.
(1) After heating the surface of the multilayer preform to 90-110 ° C,
(2) While stretching the multilayer preform longitudinally with a rod in the mold, the pressure is changed in multiple stages and high pressure air is blown.
(3) The first stage pressure (primary blow pressure) when blowing high-pressure air in multiple stages is 0.5 to 2.0 MPa (4) The final stage when blowing high-pressure air in multiple stages The pressure (secondary blow pressure) is 2 to 4 MPa.

The multilayer preform can be obtained by a known method. For example, using an injection molding machine having two injection cylinders, polyester (A) and gas barrier resin (barrier resin) are molded from the skin side and core side injection cylinders through a mold hot runner. It can be obtained by injection into the cavity.

  In the multilayer bottle manufacturing method of the present invention, the surface of the multilayer preform is preferably heated to 90 to 110 ° C. and blown, more preferably 95 ° C. to 108 ° C. When the preform heating temperature is within the above range, the blow moldability is good. Further, the barrier layer or the polyester (A) layer is not cold-drawn and whitened, or the barrier layer is not crystallized and whitened, and the delamination resistance is improved. In addition, the measurement of surface temperature uses an infrared radiation thermometer, and emissivity can be measured on condition of 0.95 normally. By the way, when the preform is heated, the heating is usually performed with several or more heaters, but the output balance of the heaters is also important. In addition, since the appropriate heater output balance, preform heating temperature, and heating time vary depending on the outside air temperature and the preform temperature, there is a caution.

In the multilayer bottle manufacturing method of the present invention, it is preferable to blow high-pressure air by changing the pressure in multiple stages (at least in two stages) while stretching the multilayer preform longitudinally with a rod in the mold. By changing the pressure and blowing in multiple stages, the formability from the multilayer preform to the multilayer bottle becomes good, and the delamination resistance becomes good.

In the multilayer bottle manufacturing method of the present invention, it is preferable that the first-stage pressure (primary blow pressure) when high-pressure air is blown in multiple stages is 0.5 to 2.0 MPa. More preferably, it is 0.7-1.5 MPa, More preferably, it is 0.8-1.3 MPa. By setting the first-stage pressure within the above range, the shapeability from the multilayer preform to the multilayer bottle becomes good, and the delamination resistance becomes good.

In the multilayer bottle manufacturing method of the present invention, the final stage pressure (secondary blow pressure) when blowing high-pressure air in multiple stages is preferably 2 to 4 MPa. More preferably, it is 2.2-3.5 MPa, More preferably, it is 2.4-3.0 MPa. By setting the final stage pressure within the above range, the formability from the multilayer preform to the multilayer bottle becomes good, and the delamination resistance becomes good.

In the multilayer bottle manufacturing method of the present invention, the time (primary blow delay time) from the start of stretching the multilayer preform with a rod to the start of the first stage blow may be 0.1 to 0.5 seconds. preferable. More preferably, it is 0.2-0.4 second, More preferably, it is 0.25-0.38 second. By setting it as the said range, the shaping property from a multilayer preform to a multilayer bottle becomes favorable, and delamination-proof property becomes favorable.

In the multilayer bottle manufacturing method of the present invention, the operating pressure of the rod is preferably 0.2 to 1.0 MPa. More preferably, it is 0.3-0.8 MPa, More preferably, it is 0.4-0.7 MPa. By setting it as the said range, the shaping property from a multilayer preform to a multilayer bottle becomes favorable, and delamination-proof property becomes favorable.

In the multilayer bottle manufacturing method of the present invention, it is preferable that the time for applying the first-stage pressure (primary blow time) when blowing high-pressure air in multiple stages is 0.1 to 0.5 seconds. More preferably, it is 0.2-0.4 second, More preferably, it is 0.25-0.38 second. By setting it as the said range, the shaping property from a multilayer preform to a multilayer bottle becomes favorable, and delamination-proof property becomes favorable.

In the multilayer bottle manufacturing method of the present invention, it is preferable that the time for applying the final stage pressure (secondary blow time) when blowing high-pressure air in multiple stages is 1 to 3 seconds. More preferably, it is 1.2-2.8 second, More preferably, it is 1.5-2.5 second. By setting it as the said range, the shaping property from a multilayer preform to a multilayer bottle becomes favorable, and delamination-proof property becomes favorable.

By blow-molding a multilayer preform by the method of the present invention, a multilayer bottle in which the degree of orientation of the body barrier layer satisfies the following formula can be produced.
20 ≦ body barrier layer orientation (average value) ≦ 45
The degree of body barrier layer orientation is more preferably 25 ≦ body part barrier layer orientation (average value) ≦ 45.
Here, the degree of orientation is obtained by the following formula from the refractive index of the barrier layer measured at 23 ° C. using an Abbe refractometer.
Degree of orientation = [{n (x) + n (y)} / 2−n (z)] × 1000
(N (x): refractive index in the bottle height direction, n (y): refractive index in the bottle circumferential direction, n (z): refractive index in the thickness direction)
Similarly, the orientation degree (average value) of the bottom barrier layer obtained in the same manner is in the range of 20 to 45, more preferably in the range of 25 to 45.

  The degree of orientation is used as an index representing the degree of orientation of polymer molecules, that is, the degree of crystallinity. The higher the degree of orientation, the higher the proportion of molecules that are regularly ordered. The degree of orientation of the barrier layer is controlled by the blowing conditions. By appropriately controlling the primary blow pressure, primary blow delay time, secondary blow pressure, heating temperature of the multilayer preform surface, etc. so that the degree of orientation is in the above range, the barrier layer is uniformly stretched and blow molded. The strain of the later barrier layer can be increased. Thereby, the adhesion between the layers of the multilayer bottle is improved, and the delamination resistance is improved.

By blow-molding a multilayer preform by the method of the present invention, a multilayer bottle whose barrier layer thickness satisfies the following conditions can be produced.
0 ≦ b / a × 100 ≦ 200
(A: trunk barrier layer average thickness (μm), b: bottom barrier layer average thickness (μm))
More preferably, it satisfies 0 ≦ b / a × 100 ≦ 150.
When the value of b / a × 100 is larger than 100, it means that the thickness of the bottom barrier layer is thicker than the thickness of the barrier layer (trunk), and when smaller than 100, the thickness of the bottom barrier layer is the trunk barrier layer. It means that it is thinner than the thickness. When 0, it means that there is no barrier layer at the bottom. In this case, if there is no barrier layer at the entire bottom, the barrier properties of the bottle will be reduced. In addition, a barrier layer is preferably present on the other bottom.

  When the thickness of the bottom barrier layer with respect to the thickness of the trunk barrier layer is within the above range, there is little change in the thickness of the barrier layer from the trunk to the grounding portion, and the thickness changes gradually. Therefore, when an impact is applied to the bottle such as when the bottle is dropped, the impact energy applied to the barrier layer is not concentrated on a part of the bottle but spreads and relaxes throughout the bottle barrier layer, so that delamination hardly occurs. Furthermore, since the deformation of the barrier layer is reduced when an impact is applied to the bottle, delamination does not easily occur. Moreover, even in a bottle shape including an uneven portion and a bent portion, delamination hardly occurs because the impact is alleviated in the entire barrier layer. Therefore, the shape of the multi-layer bottle is not limited to a shape with few concavo-convex parts and bent parts, and the degree of freedom in design increases.

In order to control the thickness of the barrier layer of the multi-layer bottle within the above-described range, setting conditions during blow molding is extremely important. As described above, blow molding is obtained by heating a preform and blowing high-pressure air while stretching the preform in a longitudinal direction with a rod in a mold. The bottle is stretched differently depending on the blowing conditions such as preform heating temperature, heating time, stretching rod speed, timing for blowing high-pressure air, and high-pressure air pressure. Therefore, by setting these blowing conditions within the condition range of the present invention, the barrier layer thickness can be controlled within the above-mentioned appropriate range, and a multilayer bottle having good delamination resistance can be obtained.

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. 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, first, the polyester (A) is injected, Next, the resin constituting the barrier layer and the polyester (A) are injected at the same time, then the required amount of polyester (A) is injected to fill the mold cavity, thereby forming a three-layer structure (polyester (A) layer / barrier layer / A multilayer preform of polyester (A) layer 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 By injecting the resin constituting the barrier layer alone and finally injecting the polyester (A) to fill the mold cavity, a five-layer structure (polyester (A) layer / barrier layer / polyester (A) layer / A multilayer preform of barrier layer / 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.

  Further, even if the barrier layer distribution in the multilayer preform is inappropriate, the barrier layer thickness of the multilayer bottle after blow does not fall within the above-mentioned range, so the preform must be designed appropriately in consideration of the draw ratio and the like. In addition, the draw ratio when it shape | molds from a preform to a bottle is about 9 to 13 times in general.

  In the multilayer bottle obtained by the production method of the present invention, the weight of the barrier layer is preferably 1 to 20% by weight, more preferably 2 to 15% by weight, particularly preferably 3 to 10%, based on the total weight of the multilayer bottle. % By weight. 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.

  The multilayer bottle obtained by the production method of the present invention has good shapeability, and delamination due to dropping or impact hardly occurs. 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, etc. 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) Degree of Orientation Using an Atago Abbe refractometer DR-M2, using a sodium D line (589 nm) at 23 ° C. and measuring the refractive index of the barrier layer, the degree of orientation was determined by the above formula. .
(2) Shapeability It was visually determined whether or not the petaloid shape at the bottom of the molded multilayer bottle was transferred well from the mold.
(3) Delamination Height Based on ASTM D2463-Procedure B, the delamination height was determined and evaluated by a container drop test. 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.
(4) Oxygen transmission coefficient (OTR)
Measurement was performed according to ASTM D3985 in an atmosphere of 23 ° C. and 50% relative humidity. The measurement used Modern Controls make and OX-TRAN 10 / 50A. In addition, OTR of the barrier layer was measured by taking out the molded bottle carefully and taking out only the barrier layer. In addition, when it is difficult to take out only the barrier layer, after cutting the bottle body composed of the polyester A layer and the barrier layer into a sheet and measuring the OTR in multiple layers, the thickness of each layer is measured using a microscope or the like. By measuring and using the OTR value of the known polyester A layer, the OTR value of only the barrier layer can be calculated. Alternatively, the OTR of the barrier layer can be calculated by measuring the OTR of the bottle and determining the surface area and thickness of each layer of the bottle.

<Example 1>
Under the following conditions, a three-layer preform (27 g) composed of a polyester layer / barrier layer / polyester layer was injection molded and cooled. The obtained preform was heated to perform biaxial stretch blow molding to obtain a multilayer bottle. Table 1 shows the blow conditions. Table 2 shows the barrier layer thickness of the multilayer bottle, and Table 3 shows the OTR, delamination property, and orientation degree.
(Used resin)
Polyester layer: Polyethylene terephthalate (RT543C, manufactured by Nihon Unipet) having an intrinsic viscosity (a mixed solvent of phenol / tetrachloroethane = 6/4 (weight ratio), measurement temperature 30 ° C.) is 0.75 dl / g.
Barrier layer: Polyamide MXD6 (MX nylon S6007 (solid phase polymerization product) manufactured by Mitsubishi Gas Chemical Co., Ltd.) having a relative viscosity (resin 1 g / 96% sulfuric acid 100 ml, measurement temperature 25 ° C.) 2.70.
(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: 260 ° 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 petaloid 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: 101 ° C
Stretching rod pressure: 0.5 MPa
Primary blow pressure: 1.1 MPa
Secondary blow pressure: 2.5 MPa
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 ℃

<Examples 2 to 4, Comparative Examples 1 and 2>
A multilayer bottle was obtained in the same manner as in Example 1 except that the blowing conditions were changed to those shown in Table 1. In Comparative Example 1, high pressure air was blown in two stages without changing the pressure. Table 2 shows the barrier layer thickness. Table 3 shows the OTR, formability, delamination property, and orientation degree.

  As shown in the above examples, the multi-layer bottle produced by the blowing conditions of the present invention showed excellent delamination resistance and shapeability, but did not satisfy the blowing conditions of the present invention. The bottle was inferior in delamination resistance and shaping.

Claims (9)

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 a dicarboxylic acid component containing 80 mol% or more of terephthalic acid and ethylene glycol. A method for producing a multilayer bottle by molding a multilayer preform mainly composed of a thermoplastic polyester resin obtained by polymerizing a diol component containing 80 mol% or more, wherein the multilayer preform is represented by the following (1) to ( 4. A method for producing a multi-layer bottle, characterized in that biaxial stretching blow molding is performed by a method that satisfies the condition of 4).
(1) After heating the surface of the multilayer preform to 90-110 ° C,
(2) While stretching the multilayer preform longitudinally with a rod in the mold, the pressure is changed in multiple stages and high pressure air is blown.
(3) The first stage pressure (primary blow pressure) when blowing high pressure air in multiple stages is 0.5 to 2.0 MPa. (4) The final stage when blowing high pressure air in multiple stages The pressure (secondary blow pressure) is 2 to 4 MPa.   The multilayer bottle manufacturing method according to claim 1, wherein the operating pressure of the rod is 0.2 to 1.0 MPa. The multi-layer bottle production according to claim 1 or 2, wherein a time period (primary blow delay time) from the start of stretching the multi-layer preform with a rod to the start of the first stage blow is 0.1 to 0.5 seconds. Method. The multi-layer bottle manufacturing method according to any one of claims 1 to 3, wherein a time for applying the pressure in the first stage (primary blowing time) is 0.1 to 0.5 seconds. The multi-layer bottle manufacturing method according to any one of claims 1 to 4, wherein a time (secondary blow time) for applying the final stage pressure is 1 to 3 seconds. The barrier layer is mainly a polycondensation of a diamine component containing 70 mol% or more of metaxylylenediamine and a dicarboxylic acid component containing 50 mol% or more of an α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms. The multilayer bottle manufacturing method in any one of Claims 1-5 comprised by the polyamide obtained by this. The multilayer bottle manufacturing method according to any one of claims 1 to 6, wherein the degree of orientation (average value) of the barrel barrier layer of the multilayer bottle manufactured by blow molding the multilayer preform is 20 or more and 45 or less. . With respect to the barrier layer of the multilayer bottle manufactured by blow-molding the multilayer preform, when the average thickness of the body barrier layer is a (μm) and the average thickness of the bottom barrier layer is b (μm), 0 ≦ b / The multilayer bottle manufacturing method according to claim 1, wherein the condition of a × 100 ≦ 200 is satisfied. The multilayer bottle manufacturing method according to claim 1, wherein the barrier layer is made of a material that satisfies the following condition (a).
(A) The oxygen permeability coefficient (average value) measured under the conditions of a temperature of 23 ° C. and a relative humidity of 60% RH of the barrel barrier layer of the multilayer bottle produced by blow molding the multilayer preform is 0.2 cc・ Mm / (m ² (Day / atm) or less