JP7463705B2 - Multilayer preform, method for producing multilayer preform, and method for producing multilayer container - Google Patents

Description

The present disclosure relates to a multilayer preform, a method for manufacturing a multilayer preform, and a method for manufacturing a multilayer container.

Polyesters such as polyethylene terephthalate are widely used in the manufacture of containers for filling beverages and the like, because they are inexpensive and have excellent mechanical properties, chemical stability, heat resistance, gas barrier properties, and transparency. Such containers are obtained by preparing a polyester preform and blow molding the preform.

In recent years, polyester recycled by various methods has been used to manufacture containers in order to reduce the environmental impact (for example, see Patent Document 1). Patent Document 1 discloses a preform that uses recycled polyester as an intermediate layer material.

However, due to cost considerations, most polyesters on the market are polymerized using antimony catalysts (hereafter referred to as antimony-catalyzed polyesters), and most of the polyesters used as raw materials for recycling are also antimony-catalyzed polyesters.

However, repeated recycling raises concerns about accumulated contaminants that are not removed and the leaching of antimony catalysts into the contents. In addition, in convenience stores and other places, containers filled with contents are placed upright and heated in hot water heaters before being sold, and in such a heated state the leaching of antimony is particularly problematic.

Japanese Patent Application Laid-Open No. 7-178801

The present disclosure has been made in consideration of these points, and aims to provide a multi-layer preform, a method for manufacturing a multi-layer preform, and a method for manufacturing a multi-layer container that can improve the hygiene of the multi-layer container and reduce the environmental impact of the multi-layer container.

The multilayer preform according to one embodiment is a multilayer preform having a body and a bottom, an inner layer made of a sheet molding or a film, and an outer layer disposed outside the inner layer and integrally formed with the inner layer, the inner layer being made of virgin polyester, and the outer layer being made of recycled polyester.

In one embodiment of the multilayer preform, the thickness of the outer layer in the body portion may be greater than the thickness of the inner layer.

In one embodiment of the multilayer preform, the thickness of the outer layer in the body portion may be 0.3 to 25 times the thickness of the inner layer.

In one embodiment of the multilayer preform, the thickness of the inner layer in the body portion may be 0.1 mm or more and 2.9 mm or less.

In one embodiment of the multilayer preform, the inner surface of the outer layer may be entirely covered by the inner layer.

The method for producing a multilayer preform according to one embodiment includes the steps of preparing a mold assembly having a cavity-side mold and a core-side mold including a core, mounting a sheet molded body or a film on the core of the core-side mold, inserting the core on which the sheet molded body or the film is mounted into the cavity-side mold, and forming a multilayer preform having an inner layer made of the sheet molded body or the film and an outer layer disposed outside the inner layer and integrally formed with the inner layer by injecting an injection resin into the space between the cavity-side mold and the sheet molded body or the film mounted on the core, the inner layer being made of virgin polyester and the outer layer being made of recycled polyester.

A method for manufacturing a multilayer container according to one embodiment includes the steps of producing a multilayer preform by the method for manufacturing a multilayer preform according to the present disclosure, and subjecting the multilayer preform to blow molding.

According to the present disclosure, it is possible to improve the hygiene of multi-layer containers and reduce the environmental impact of multi-layer containers.

FIG. 1 is a partial vertical cross-sectional view showing a multi-layer container according to one embodiment. FIG. 2 is a vertical cross-sectional view of a multi-layer preform according to one embodiment. FIG. 3 is a diagram illustrating a method for manufacturing a multi-layer preform according to one embodiment. FIG. 4 is a diagram illustrating a method for manufacturing a multi-layer preform according to one embodiment. FIG. 5 is a diagram illustrating a method for manufacturing a multi-layer preform according to one embodiment. FIG. 6 is a diagram illustrating a method for manufacturing a multi-layer preform according to one embodiment.

An embodiment will be described below with reference to the drawings. Figures 1 to 6 are diagrams showing an embodiment. Each of the figures shown below is a schematic diagram. Therefore, the size and shape of each part are appropriately exaggerated to make it easier to understand. In addition, it is possible to carry out appropriate modifications within the scope of the technical concept. In each of the figures shown below, the same parts are given the same reference numerals, and some detailed explanations may be omitted. In addition, the numerical values such as dimensions of each member and the material names described in this specification are examples of an embodiment, and are not limited to these, and can be selected and used as appropriate. In this specification, terms that specify shapes and geometric conditions, such as parallel, orthogonal, and vertical, are intended to include substantially the same state in addition to their strict meanings.

<Multilayer containers and multilayer preforms>
First, the multilayer container 10 manufactured from the multilayer preform 23 according to the present embodiment and the multilayer preform 23 according to the present embodiment will be described with reference to Figures 1 and 2. In this specification, "upper" and "lower" refer to the upper and lower sides of the multilayer container 10 and the multilayer preform 23, respectively, when they are upright (Figures 1 and 2).

(Multilayer container)
First, an overview of a multilayer container 10 will be described with reference to Fig. 1. The multilayer container 10 is obtained by subjecting a multilayer preform 23 to blow molding.

As shown in FIG. 1, the multilayer container 10 includes an inner layer 11 and an outer layer 12. The multilayer container 10 according to the present disclosure may further include a vapor deposition film (not shown) located on the inner surface of the inner layer 11.

In this embodiment, the multi-layer container 10 has a mouth 13, a shoulder 14, a body 15, and a bottom 16. The mouth 13 has a threaded portion 17 to which a cap (not shown) is screwed, a cap 18 provided below the threaded portion 17, and a support ring 19 provided below the cap 18.

The shoulder 14 is located between the mouth 13 and the body 15, and has a shape in which the outer diameter gradually expands downward.

The body 15 has a panel portion 22. This configuration makes it possible to prevent deformation of the container due to an increase or decrease in internal pressure when the heated contents are filled into the multi-layer container 10 or when the contents are heated after filling.

The bottom 16 has a centrally located recessed portion 20 and a grounding portion 21 provided around the recessed portion 20. This configuration makes it possible to prevent deformation of the container due to an increase or decrease in internal pressure when the multi-layer container 10 is filled with heated contents or when the contents are heated after filling.

The volume/weight of such a multilayer container 10 is preferably 5 mL/g or more and 50 mL/g or less, and more preferably 8 mL/g or more and 45 mL/g or less. By having the volume/weight of the multilayer container 10 be 5 mL/g or more, the blow moldability of the multilayer container 10 can be improved. Furthermore, by having the volume/weight of the multilayer container 10 be 50 mL/g or less, the heat resistance and strength of the multilayer container 10 can be improved.

In addition, the outer layer 12 of the multilayer container 10 is composed of recycled polyester as described below, and the content of this recycled polyester is preferably 40 parts by mass or more and 95 parts by mass or less, and more preferably 60 parts by mass or more and 80 parts by mass or less, relative to 100 parts by mass of the total amount of the resin material contained in the multilayer container 10. By having the content of recycled polyester be 40 parts by mass or more relative to 100 parts by mass of the total amount of the resin material contained in the multilayer container 10, the environmental load reduction properties of the multilayer container 10 can be further improved. By having the content of recycled polyester be 95 parts by mass or less relative to 100 parts by mass of the total amount of the resin material contained in the multilayer container 10, it is possible to prevent the recycled polyester constituting the outer layer 12 in the multilayer container 10 from being exposed from the inner surface of the inner layer 11.

Furthermore, the eluted antimony concentration of the multilayer container 10 is preferably less than 6 ppb, and more preferably less than 3 ppb. The eluted antimony concentration of less than 6 ppb satisfies the value recommended by the 21 CFR (Chapter 21 of the Federal Law) of the U.S. Food and Drug Administration (FDA), which is preferable. Depending on the type of contents filled in the multilayer container 10, a trace amount of antimony may already be contained. The eluted antimony concentration of the multilayer container 10 of less than 3 ppb can reduce the amount of antimony ultimately dissolved in the contents. In this embodiment, the "eluted antimony concentration of the multilayer container" refers to the concentration of antimony contained in the water removed from the multilayer container 10 after filling the multilayer container 10 with ultrapure water at 23°C, leaving the multilayer container 10 filled with water in a lying position in an environment of 70°C for 14 days.

Such a multi-layer container 10 can prevent antimony and other substances from leaching into the contents even when the multi-layer container 10 is filled with high-temperature contents or when the contents are heated after filling. In this way, the multi-layer container 10 has high hygienic properties and can be suitably used as a heating container.

(Inner layer of multi-layer container)
Next, the inner layer 11 of the multi-layer container 10 will be described. The inner layer 11 is characterized by being composed of virgin polyester selected from manganese catalyzed polyester, titanium catalyzed polyester, aluminum catalyzed polyester, lithium catalyzed polyester, and germanium catalyzed polyester. By adopting such a configuration, even if recycled polyester is used for the outer layer 12, antimony elution into the contents can be prevented. As described above, the inner layer 11 of the multi-layer container 10 is composed of virgin polyester, and the content of this virgin polyester is preferably 20 parts by mass or more and 100 parts by mass or less, and more preferably 60 parts by mass or more and 90 parts by mass or less, relative to 100 parts by mass of the total amount of the resin material contained in the inner layer 11. By having a virgin polyester content of 20 parts by mass or more, it is possible to improve the adhesion with the outer layer 12 composed of recycled polyester as described later, and delamination between the inner layer 11 and the outer layer 12 can be suppressed. In addition, by having a virgin polyester content of 60 parts by mass or more, it is possible to further improve the adhesion with the outer layer 12 composed of recycled polyester, and it is possible to more effectively suppress delamination between the inner layer 11 and the outer layer 12. Furthermore, by having the virgin polyester content of 90 parts by mass or less, when a resin having a function such as a barrier property is blended with the virgin polyester, the dispersion efficiency of the resin in the inner layer 11 can be improved. Note that it is preferable that the inner layer 11 does not contain a mechanical polyester, which will be described later. This can improve the hygiene of the multilayer container 10.

In this disclosure, "virgin polyester" refers to polyester that has not been subjected to the recycling process described below, i.e., unused polyester.

Examples of manganese catalysts include fatty acid manganese salts such as manganese acetate, manganese carbonate, manganese chloride, manganese acetylacetonate salts, and manganese hydroxide.

Examples of titanium catalysts include titanium alkoxides such as tetra-n-propyl titanate, tetra-i-propyl titanate, tetra-n-butyl titanate, tetra-n-butyl titanate tetramer, tetra-t-butyl titanate, tetracyclohexyl titanate, tetraphenyl titanate, and tetrabenzyl titanate, titanium oxides obtained by hydrolysis of titanium alkoxides, titanium acetate, titanium oxalate, potassium titanium oxalate, sodium titanium oxalate, potassium titanate, sodium titanate, titanic acid-aluminum hydroxide mixture, titanium chloride, titanium chloride-aluminum chloride mixture, titanium bromide, titanium fluoride, potassium hexafluorotitanate, cobalt hexafluorotitanate, manganese hexafluorotitanate, ammonium hexafluorotitanate, and titanium acetylacetonate.

Examples of aluminum catalysts include aluminum tris(acetylacetate), aluminum monoacetylacetonate bis(ethylacetoacetate), and ethylacetoacetate aluminum diisopropylate.

Examples of lithium catalysts include ethyllithium, propyllithium, n-butyllithium, sec-butyllithium, tert-butyllithium, and phenyllithium.

Examples of germanium catalysts include germanium dioxide, germanium tetroxide, germanium tetramethoxide, germanium tetraethoxide, germanium tetrapropoxide, germanium tetrabutoxide, germanium tetrapentoxide, and germanium tetrahexoxide.

In this embodiment, "polyester" means a copolymer of a dicarboxylic acid compound and a diol compound.

Examples of dicarboxylic acid compounds include malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, sebacic acid, dodecanedioic acid, eicosanedioic acid, pimelic acid, azelaic acid, methylmalonic acid, ethylmalonic acid, adamantanedicarboxylic acid, norbornenedicarboxylic acid, cyclohexanedicarboxylic acid, decalindicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 5-sodiumsulfoisophthalic acid, phenylendanedicarboxylic acid, anthracenedicarboxylic acid, phenanthrenedicarboxylic acid, 9,9'-bis(4-carboxyphenyl)fluorene acid, and ester derivatives thereof.

Examples of diol compounds include ethylene glycol, 1,2-propanediol, 1,3-propanediol, butanediol, 2-methyl-1,3-propanediol, hexanediol, neopentyl glycol, cyclohexanedimethanol, cyclohexanediethanol, decahydronaphthalenedimethanol, decahydronaphthalenediethanol, norbornanedimethanol, norbornanediethanol, tricyclodecanedimethanol, tricyclodecaneethanol, tetracyclododecanedimethanol, tetracyclododecanediethanol, decalindimethanol, decalindiethanol, 5-cyclohexane ... -Methylol-5-ethyl-2-(1,1-dimethyl-2-hydroxyethyl)-1,3-dioxane, cyclohexanediol, bicyclohexyl-4,4'-diol, 2,2-bis(4-hydroxycyclohexylpropane), 2,2-bis(4-(2-hydroxyethoxy)cyclohexyl)propane, cyclopentanediol, 3-methyl-1,2-cyclopentadiol, 4-cyclopentene-1,3-diol, adamantanediol, paraxylene glycol, bisphenol A, bisphenol S, styrene glycol, trimethylolpropane, and pentaerythritol.

Among polyesters, polyethylene terephthalate, which is a copolymer of terephthalic acid and ethylene glycol, or modified polyethylene terephthalate, which is a copolymer of polyethylene terephthalate and a copolymerization monomer, is preferred.

The polyester may contain monomers other than the dicarboxylic acid compound and the diol compound as long as the characteristics of this embodiment are not impaired, but the content of such monomers is preferably 10 mol % or less, more preferably 5 mol % or less, and even more preferably 3 mol % or less, based on the total constituent units.

The inner layer 11 may contain additives, as long as they do not impair the characteristics of this embodiment, such as oxygen absorbers, gas barrier resins (polyamides such as nylon 6, nylon 6,6, and polymetaxylylene adipamide (MXD6)), plasticizers, UV stabilizers, antioxidants, color inhibitors, matting agents, deodorants, flame retardants, weather resistance agents, antistatic agents, thread friction reducers, slip agents, mold release agents, antioxidants, ion exchange agents, acetaldehyde absorbers (e.g., AA Scavengers manufactured by Color Matrix), and colorants.

In the multilayer container 10 of this embodiment, as shown in FIG. 1, the inner layer 11 is provided from the upper end of the mouth 13 to the bottom 16, and covers the entire inner surface of the outer layer 12. With this configuration, recycled polyester is used for the outer layer 12, and antimony can be effectively prevented from leaching into the contents even when the container is stored heated in a vending machine or the like while lying on its side.

The thickness of the inner layer 11 in the multilayer container 10 is preferably 0.01 mm or more and 0.33 mm or less, and more preferably 0.025 mm or more and 0.3 mm or less, in any region of the body 15 of the multilayer container 10. By making the thickness of the inner layer 11 0.01 mm or more, even if recycled polyester is used for the outer layer 12, it is possible to prevent the recycled polyester constituting the outer layer 12 from being exposed from the inner surface of the inner layer 11. Therefore, in the multilayer container 10, it is possible to effectively prevent antimony from eluting into the contents. In addition, by making the thickness of the inner layer 11 0.33 mm or less, it is possible to increase the proportion of the outer layer 12 in the multilayer container 10, and it is possible to further improve the environmental load reduction of the multilayer container 10.

(Outer layer of multi-layer container)
Next, the outer layer 12 of the multilayer container 10 will be described. The outer layer 12 is made of recycled polyester. By adopting such a configuration, the environmental load reduction of the multilayer container 10 of the present embodiment can be improved. As described above, the outer layer 12 of the multilayer container 10 is made of recycled polyester, and the content of this recycled polyester is preferably 20 parts by mass or more and 100 parts by mass or less, and more preferably 60 parts by mass or more and 90 parts by mass or less, relative to 100 parts by mass of the total amount of the resin material contained in the outer layer 12. By having the recycled polyester content of 20 parts by mass or more, the environmental load reduction of the multilayer container 10 can be further improved. In addition, by having the recycled polyester content of 60 parts by mass or more, the environmental load reduction of the multilayer container 10 can be further improved. Furthermore, by having the recycled polyester content of 90 parts by mass or less, for example, when a resin having a function such as a barrier property is blended with the recycled polyester, the dispersion efficiency of the resin in the outer layer 12 can be improved.

In this embodiment, "recycled polyester" refers to chemically recycled polyester or mechanically recycled polyester.

Chemically recycled polyester refers to polyester obtained by breaking down polyester containers down to the monomer level and then repolymerizing them.

Mechanically recycled polyester refers to polyester obtained by sorting, crushing, and washing polyester containers to remove contaminants and foreign matter, obtaining flakes, and then treating the flakes for a certain period of time under high temperature and reduced pressure to remove contaminants from within the resin.

To the extent that the characteristics of this embodiment are not impaired, the outer layer 12 may contain additives, such as oxygen absorbers, gas barrier resins (polyamides such as nylon 6, nylon 6,6, and polymetaxylylene adipamide (MXD6)), plasticizers, UV stabilizers, antioxidants, color inhibitors, matting agents, deodorants, flame retardants, weather resistance agents, antistatic agents, thread friction reducers, slip agents, mold release agents, antioxidants, ion exchange agents, acetaldehyde absorbers (e.g., AA Scavengers manufactured by Color Matrix), and colorants.

The thickness of the outer layer 12 in the multilayer container 10 is preferably 0.04 mm or more and 0.52 mm or less, and more preferably 0.1 mm or more and 0.4 mm or less, in any region of the body 15 of the multilayer container 10. By making the thickness of the outer layer 12 0.04 mm or more, the proportion of the outer layer 12 in the multilayer container 10 can be increased, and the environmental load reduction properties of the multilayer container 10 can be further improved. Furthermore, by making the thickness of the outer layer 12 0.52 mm or less, the multilayer container 10 can be made thinner.

(Vapor-deposited film)
As described above, the multilayer container 10 may further include a vapor deposition film located on the inner surface of the inner layer 11. This can improve the gas barrier properties of the multilayer container 10.

Examples of vapor-deposited films include vapor-deposited films made of metals such as aluminum, inorganic oxides such as aluminum oxide, silicon oxide, magnesium oxide, calcium oxide, zirconium oxide, titanium oxide, boron oxide, hafnium oxide, and barium oxide, organic silicon compounds such as hexamethyldisiloxane, and hard carbon films such as diamond-like carbon (DLC) films.

The hard carbon film made of DLC is also called i-carbon film or hydrogenated amorphous carbon film (a-C:H), and is an amorphous carbon film mainly composed of SP3 bonds.

The thickness of the deposited film is not particularly limited and can be, for example, 1 nm or more and 150 nm or less.

The deposition film can be formed by a conventional method, for example, physical vapor deposition methods (PVD method) such as vacuum deposition, sputtering, and ion plating, as well as chemical vapor deposition methods (CVD method) such as plasma chemical vapor deposition, thermal chemical vapor deposition, and photochemical vapor deposition.

(Multi-layer preform)
Next, the multilayer preform 23 according to the present embodiment will be described. The multilayer preform 23 is used to manufacture the multilayer container 10. As shown in Fig. 2, the multilayer preform 23 includes an inner layer 24 and an outer layer 25 that is disposed outside the inner layer 24 and is integrally formed with the inner layer 24. The inner layer 24 is the innermost layer of the multilayer preform 23, and the outer layer 25 is the outermost layer of the multilayer preform 23.

In this embodiment, the multilayer preform 23 has a mouth portion 26, a body portion 27, and a bottom portion 28, as shown in FIG. 2. Of these, the mouth portion 26 corresponds to the mouth portion 13 of the multilayer container 10 described above, and has substantially the same shape as the mouth portion 13.

The body 27 corresponds to the shoulder 14 and body 15 of the multi-layer container 10 described above. The body 27 has a large diameter portion 27a on the mouth 26 side, a reduced diameter portion 27b provided below the large diameter portion 27a, and a small diameter portion 27c provided below the reduced diameter portion 27b.

The large diameter portion 27a is the portion of the body 27 that has the largest outer diameter, and has a cylindrical shape with a substantially uniform outer diameter. The thickness of the large diameter portion 27a is substantially constant overall.

The reduced diameter portion 27b has a shape in which the outer diameter gradually decreases toward the bottom. The thickness of the reduced diameter portion 27b gradually increases toward the bottom.

The small diameter portion 27c is the portion of the body 27 with the smallest outer diameter, and has a cylindrical shape with a substantially uniform outer diameter. The thickness of the small diameter portion 27c gradually increases downward from its upper portion, and the thickness of the area other than the upper portion is substantially constant overall. In the area of the small diameter portion 27c where the thickness changes, the inner layer 24 of the multilayer preform 23 is composed of the reduced diameter portion sheet 61b of the sheet molding 60 described later, and in the area of the small diameter portion 27c where the thickness is substantially constant, the inner layer 24 of the multilayer preform 23 is composed of the small diameter portion sheet 61c of the sheet molding 60 described later.

The bottom 28 corresponds to the bottom 16 of the multi-layer container 10 described above and has an approximately hemispherical shape.

(Inner layer of multi-layer preform)
Next, a description will be given of the inner layer 24 of the multi-layer preform 23. The material constituting the inner layer 24 of the multi-layer preform 23 is the same as the material of the inner layer 11 of the multi-layer container 10.

In this embodiment, the inner layer 24 of the multilayer preform 23 is composed of a sheet molded body 60. This sheet molded body 60 is obtained by vacuum molding a single sheet-like member composed of virgin polyester. The sheet molded body 60 is composed of virgin polyester, and the content of this virgin polyester is preferably 20 parts by mass or more and 100 parts by mass or less, and more preferably 60 parts by mass or more and 90 parts by mass or less, relative to 100 parts by mass of the total amount of the resin material contained in the sheet molded body 60. By having a virgin polyester content of 20 parts by mass or more, it is possible to improve the adhesion with the outer layer 25 composed of recycled polyester as described later, and delamination between the inner layer 24 and the outer layer 25 can be suppressed. In addition, by having a virgin polyester content of 60 parts by mass or more, it is possible to further improve the adhesion with the outer layer 25 composed of recycled polyester, and it is possible to more effectively suppress delamination between the inner layer 24 and the outer layer 25. Furthermore, by having a virgin polyester content of 90 parts by mass or less, when a resin having a function such as a barrier property is blended with the virgin polyester, the dispersion efficiency of the resin in the inner layer 24 can be improved. It is preferable that the inner layer 24 does not contain mechanical polyester. This can improve the hygiene of the multilayer container 10 produced from the multilayer preform 23.

As shown in FIG. 2, the sheet molding 60 has an overall cylindrical shape with a bottom, and includes a substantially cylindrical body sheet 61 and a bottom sheet 62 provided below the body sheet 61. In this case, the inner layer 24 formed by the sheet molding 60 can cover the entire inner surface of the outer layer 25 of the multilayer preform 23, so that the inner layer 11 can cover the entire inner surface of the outer layer 12 even in the multilayer container 10 made from the multilayer preform 23. This improves the hygiene of the multilayer container 10.

The body sheet 61 of the sheet molding 60 includes a large diameter section sheet 61a located at the top, a reduced diameter section sheet 61b provided below the large diameter section sheet 61a, and a small diameter section sheet 61c provided below the reduced diameter section sheet 61b. Of these, the large diameter section sheet 61a is the part of the body sheet 61 with the largest outer diameter, and has a cylindrical shape with a substantially uniform outer diameter. The large diameter section sheet 61a is provided so that its lower end is at the same position in the vertical direction as the lower end of the large diameter section 27a of the body 27 of the multilayer preform 23.

The reduced diameter section sheet 61b has a shape in which the outer diameter gradually decreases downward. The reduced diameter section sheet 61b is provided so that its lower end is located lower than the lower end of the reduced diameter section 27b. The reduced diameter section sheet 61b may also be provided so that its lower end is at the same position as the lower end of the reduced diameter section 27b of the body section 27 in the vertical direction.

The small diameter section sheet 61c is the part of the body sheet 61 with the smallest outer diameter, and has a cylindrical shape with a substantially uniform outer diameter. The small diameter section sheet 61c is provided so that its upper end is located lower than the upper end of the small diameter section 27c of the body 27 of the multi-layer preform 23. The small diameter section sheet 61c may be provided so that its upper end is at the same position as the upper end of the small diameter section 27c of the body 27 in the vertical direction. The large diameter section sheet 61a, the reduced diameter section sheet 61b, the small diameter section sheet 61c and the bottom sheet 62 of the body sheet 61 are integrally configured.

When forming the outer layer 25 of the multilayer preform 23 using the mold combination 70 (see FIG. 3) described below, the sheet molding 60 is attached to the core 72 of the core side mold 73 described below. At this time, since the body sheet 61 of the sheet molding 60 includes the large diameter section sheet 61a, the reduced diameter section sheet 61b provided below the large diameter section sheet 61a, and the small diameter section sheet 61c provided below the reduced diameter section sheet 61b, the sheet molding 60 can be easily attached to the core 72.

Such a sheet molded body 60 has a substantially constant thickness overall. Therefore, the thickness of the inner layer 24 in the multilayer preform 23 is substantially constant overall. The thickness of the inner layer 24 in the multilayer preform 23 is preferably 0.1 mm or more and 2.9 mm or less in any region of the body 27 of the multilayer preform 23, and more preferably 0.2 mm or more and 2.0 mm or less. By having the inner layer 24 have a thickness of 0.1 mm or more, even if recycled polyester is used for the outer layer 25, it is possible to prevent the recycled polyester constituting the outer layer 12 from being exposed from the inner surface of the inner layer 11 in the multilayer container 10 produced from the multilayer preform 23. Therefore, it is possible to effectively prevent antimony from eluting into the contents in the multilayer container 10. By having the inner layer 24 have a thickness of 2.9 mm or less, it is possible to increase the proportion of the outer layer 12 in the multilayer container 10 produced from the multilayer preform 23, and it is possible to further improve the environmental load reduction of the multilayer container 10.

As described above, the multilayer container 10 is obtained by blow molding the multilayer preform 23. In this case, the shoulder 14, body 15, and bottom 16 of the multilayer container 10 are formed by stretching the body 27 and bottom 28 of the multilayer preform 23. For this reason, the thickness of the inner layer 24 may be made thicker in the body 27 and bottom 28 of the multilayer preform 23, which have a high stretch ratio, than in the mouth 26. This effectively prevents the outer layer 12 from being exposed from the inner surface of the inner layer 11 in the multilayer container 10 after blow molding.

(Outer layer of multi-layer preform)
Next, the outer layer 25 of the multi-layer preform 23 will be described. The material constituting the outer layer 25 of the multi-layer preform 23 is the same as the material of the outer layer 12 of the multi-layer container 10. That is, the outer layer 25 of the multi-layer preform 23 is composed of recycled polyester. In this case, the content of the recycled polyester is preferably 20 parts by mass or more and 100 parts by mass or less, and more preferably 60 parts by mass or more and 90 parts by mass or less, relative to 100 parts by mass of the total amount of the resin material contained in the outer layer 25. By having the content of the recycled polyester be 20 parts by mass or more, the environmental load reduction of the multi-layer container 10 produced from the multi-layer preform 23 can be further improved. In addition, by having the content of the recycled polyester be 60 parts by mass or more, the environmental load reduction of the multi-layer container 10 produced from the multi-layer preform 23 can be further improved. Furthermore, by having the content of the recycled polyester be 90 parts by mass or less, for example, when a resin having a function such as a barrier property is blended with the recycled polyester, the dispersion efficiency of the resin in the outer layer 25 can be improved.

The outer layer 25 is obtained by injecting an injection resin onto the outer surface of the sheet molded body 60. The outer layer 25 is configured to have a varying thickness in the body 27 of the multilayer preform 23. That is, in the body 27 of the multilayer preform 23, the thickness of the outer layer 25 is generally constant in the region of the outer layer 25 corresponding to the large diameter portion sheet 61a of the sheet molded body 60. In addition, in the region of the outer layer 25 corresponding to the reduced diameter portion sheet 61b of the sheet molded body 60, the thickness of the outer layer 25 gradually increases downward. Furthermore, in the region of the outer layer 25 corresponding to the small diameter portion sheet 61c of the sheet molded body 60, the thickness of the outer layer 25 is generally constant. The thickness of the outer layer 25 is configured to increase in the order of the region corresponding to the large diameter portion sheet 61a of the sheet molded body 60, the region corresponding to the reduced diameter portion sheet 61b of the sheet molded body 60, and the region corresponding to the small diameter portion sheet 61c of the sheet molded body 60.

The thickness (radial distance) of the outer layer 25 of such a multi-layer preform 23 is preferably greater than the thickness (radial distance) of the inner layer 24 in any region of the multi-layer preform 23. This allows the amount of recycled polyester used in the multi-layer preform 23 to be increased relative to the amount of virgin polyester used. This further improves the environmental load reduction properties of the multi-layer container 10 produced from the multi-layer preform 23.

The thickness of the outer layer 25 in the multilayer preform 23 may be 0.3 to 25 times the thickness of the inner layer 24 in any region of the body 27 of the multilayer preform 23. By making the thickness of the outer layer 25 0.3 times or more the thickness of the inner layer 24, the amount of recycled polyester used in the multilayer preform 23 can be increased. This makes it possible to improve the environmental load reduction properties of the multilayer container 10 produced from the multilayer preform 23. By making the thickness of the outer layer 25 25 times or less the thickness of the inner layer 24, it is possible to prevent the recycled polyester constituting the outer layer 12 from being exposed from the inner surface of the inner layer 11 in the multilayer container 10 produced from the multilayer preform 23.

The thickness of the outer layer 25 in the multilayer preform 23 is preferably 0.5 mm or more and 4.5 mm or less, and more preferably 1.9 mm or more and 4.0 mm or less, in any region of the body 27 of the multilayer preform 23. By making the thickness of the outer layer 25 0.5 mm or more, the environmental load reduction properties of the multilayer container 10 produced from the multilayer preform 23 can be further improved. By making the thickness of the outer layer 25 4.5 mm or less, the multilayer container 10 produced from the multilayer preform 23 can be made thinner.

In this embodiment, as shown in FIG. 2, the entire inner surface of the outer layer 25 is covered with the inner layer 24. This makes it possible to prevent the recycled polyester constituting the outer layer 12 from being exposed from the inner surface of the inner layer 11 in the multilayer container 10 produced from the multilayer preform 23. This makes it possible to improve the hygiene of the multilayer container 10.

Next, the operation of this embodiment having such a configuration, that is, the manufacturing method of the multilayer preform 23 and the manufacturing method of the multilayer container 10, will be explained with reference to Figures 3 to 6.

First, a sheet-like member (not shown) made of virgin polyester is vacuum-formed to obtain a sheet-shaped body 60 (see FIG. 2) having a body sheet 61 and a bottom sheet 62.

Next, as shown in FIG. 3, a mold assembly 70 is prepared, which has a cavity side mold 71 and a core side mold 73 including a core 72. A gate (injection port) 74 for injecting the injection resin is formed in the cavity side mold 71 at a position corresponding to the bottom 28 of the multilayer preform 23. The core 72 of the core side mold 73 has a shape corresponding to the inner surface of the inner layer 24 of the multilayer preform 23.

Next, as shown in FIG. 4, the sheet molding 60 is attached to the core 72 of the core side mold 73. In this case, for example, the sheet molding 60 may be adsorbed to the core 72 by a vacuum device (not shown) of the mold combination 70.

Next, as shown in FIG. 5, the core 72 with the sheet molding 60 attached thereto is inserted into the cavity side mold 71. At this time, the core 72 is first brought close to the cavity side mold 71, and the core 72 is inserted into the cavity side mold 71. In this manner, the cavity side mold 71 and the core side mold 73 are clamped together.

Next, as shown in FIG. 6, injection resin is injected into the space between the cavity side mold 71 and the sheet molding 60 attached to the core 72. At this time, with the cavity side mold 71 and the core side mold 73 clamped, injection resin made of recycled polyester is injected from the injection resin gate 74 provided on the cavity side mold 71 into the space between the cavity side mold 71 and the sheet molding 60. The injection resin injected from the gate 74 enters between the cavity side mold 71 and the sheet molding 60. As a result, a multi-layer preform 23 is formed, which has an inner layer 24 made of the sheet molding 60 and an outer layer 25 arranged outside the inner layer 24 and formed integrally with the inner layer 24. At this time, the inner layer 24 is made of virgin polyester, and the outer layer 25 is made of recycled polyester.

The resulting multilayer preform 23 is then removed from the mold assembly 70.

Next, we will explain the manufacturing method of the multi-layer container 10.

First, a multi-layer preform 23 is produced, for example, by the method shown in Figures 3 to 6. Then, the multi-layer preform 23 is subjected to blow molding to produce a multi-layer container 10.

As described above, according to this embodiment, the multilayer preform 23 comprises an inner layer 24 made of a sheet molding 60 and an outer layer 25 arranged on the outside of the inner layer 24 and integrally formed with the inner layer 24, the inner layer 24 being made of virgin polyester and the outer layer 25 being made of recycled polyester. This makes it possible to improve the hygiene of the multilayer container 10 produced from the multilayer preform 23 and reduce the environmental impact of the multilayer container 10.

The inner layer 24 is made of a sheet molding 60 made of virgin polyester, and the outer layer 25 is made of recycled polyester. In this way, by using polyester for the inner layer 24 and the outer layer 25, it is possible to improve the adhesion between the inner layer 24 and the outer layer 25. Furthermore, by using polyester for the inner layer 24 and the outer layer 25, it is possible to improve the recyclability of the multilayer container 10.

In addition, since the inner layer 24 of the multilayer preform 23 is composed of the sheet molding 60, the multilayer preform 23 can be easily produced, which includes the inner layer 24 composed of virgin polyester and the outer layer 25 composed of recycled polyester. That is, in this case, the multilayer preform 23 including the inner layer 24 and the outer layer 25 can be easily produced using a single mold combination 70. Therefore, it is not necessary to prepare an injection molding die for forming the inner layer 24 and an injection molding die for forming the outer layer 25 and perform the injection molding process twice. Therefore, the multilayer preform 23 can be easily produced, and the productivity of the multilayer preform 23 can be improved.

In addition, since the inner layer 24 is composed of the sheet molding 60, the thickness of the inner layer 24 can be easily controlled. Therefore, the thickness of the sheet molding 60 can be easily changed as needed. Even if the thickness of the sheet molding 60 is changed, the shape of the multilayer preform 23 can be kept constant by mounting the sheet molding 60 on the core 72 of the core side mold 73 and injecting the injection resin into the space between the cavity side mold 71 and the sheet molding 60. In this case, there is no need to re-produce the mold combination 70.

Furthermore, since the inner layer 24 is formed from the sheet molded body 60, when the outer layer 25 is formed by injecting injection resin onto the outer surface of the sheet molded body 60, it is possible to reliably prevent the injection resin constituting the outer layer 25 from being exposed from the inner surface of the sheet molded body 60. This makes it possible to reliably prevent the outer layer 25 from being exposed from the inner surface of the inner layer 24 in the multilayer preform 23. Therefore, the reliability of the multilayer preform 23 can be improved in terms of hygiene, compared to when a multilayer preform having an inner layer and an outer layer is produced by, for example, co-injection molding.

In addition, according to this embodiment, the thickness of the outer layer 25 is greater than the thickness of the inner layer 24. This allows the amount of recycled polyester used in the multilayer preform 23 to be increased relative to the amount of virgin polyester used. This further improves the environmental impact reduction properties of the multilayer container 10 produced from the multilayer preform 23.

In addition, according to this embodiment, the inner surface of the outer layer 25 is covered with the inner layer 24 over its entirety. This prevents the recycled polyester constituting the outer layer 12 from being exposed from the entire inner surface of the inner layer 11 in the multilayer container 10 produced from the multilayer preform 23. This improves the sanitation of the multilayer container 10. In this case, the outer layer 25 is also present in the mouth portion 26 of the multilayer preform 23. This allows the amount of recycled polyester used in the multilayer preform 23 to be increased relative to the amount of virgin polyester used. This further improves the environmental load reduction of the multilayer container 10 produced from the multilayer preform 23. Furthermore, in this embodiment, since the inner layer 24 is composed of the sheet molded body 60, the entire inner surface of the outer layer 25 can be easily covered with the inner layer 24. That is, by covering the entire outer surface of the core 72 of the core side mold 73 with the sheet molded body 60, the entire inner surface of the outer layer 25 can be easily covered with the inner layer 24.

In the above-described embodiment, the inner layer 24 of the multilayer preform 23 is formed of the sheet molded body 60, but the present invention is not limited to this. For example, the inner layer 24 of the multilayer preform 23 may be formed of a film. In this case, a film formed of virgin polyester can be used as the film. Even in this case, the hygiene of the multilayer container 10 produced from the multilayer preform 23 can be improved and the environmental load of the multilayer container 10 can be reduced. The above-described effects can also be obtained. Furthermore, when the inner layer 24 of the multilayer preform 23 is formed of a film, a thin inner layer 24 can be easily formed. Therefore, the proportion of the outer layer 12 in the multilayer container 10 can be easily increased, and the environmental load reduction of the multilayer container 10 can be further improved.

In the above-mentioned embodiment, the inner surface of the outer layer 25 is covered entirely by the inner layer 24, but the present invention is not limited to this. For example, although not shown, the inner surface of the outer layer 25 at the mouth 26 of the multilayer preform 23 may not be covered by the inner layer 24. Even in this case, the inner surface of the outer layer 25 at the body 27 of the multilayer preform 23 is covered by the inner layer 24, so that when the multilayer container 10 produced by blow molding the multilayer preform 23 is upright, the area of the inner surface of the multilayer container 10 that comes into contact with the contents can be covered by the inner layer 11. Therefore, even if recycled polyester is used for the outer layer 25 of the multilayer preform 23, the multilayer container 10 can effectively prevent antimony from eluting into the contents.

Furthermore, in the above-described embodiment, an example has been described in which the body sheet 61 of the sheet molding 60 constituting the inner layer 24 of the multilayer preform 23 includes a large diameter section sheet 61a, a reduced diameter section sheet 61b provided below the large diameter section sheet 61a, and a small diameter section sheet 61c provided below the reduced diameter section sheet 61b, but this is not limited thereto. For example, although not shown, the body sheet 61 may have a cylindrical shape with a generally uniform outer diameter overall.

The components disclosed in the above embodiment and modified examples may be combined as necessary. Alternatively, some components may be deleted from all the components shown in the above embodiment and modified examples.

10 Multilayer container 23 Multilayer preform 24 Inner layer 25 Outer layer 60 Sheet molded body 70 Mold combination 71 Cavity side mold 72 Core 73 Core side mold

Claims (7)

A multi-layer preform having a mouth portion, a body portion, and a bottom portion,
An inner layer composed of a sheet molded body or a film;
an outer layer disposed outside the inner layer and integrally formed with the inner layer;
The inner layer is made of virgin polyester,
The outer layer is made of recycled polyester,
The content of the virgin polyester is 60 parts by mass or more and 90 parts by mass or less with respect to 100 parts by mass of a total amount of the resin material contained in the inner layer,
The content of the recycled polyester is 60 parts by mass or more and 90 parts by mass or less with respect to 100 parts by mass of a total amount of the resin material contained in the outer layer,
The inner layer does not contain mechanically recycled polyester,
A multi-layer preform , wherein a thickness of the inner layer in the body portion and a thickness of the inner layer in the bottom portion are each greater than a thickness of the inner layer in the mouth portion . The multilayer preform according to claim 1, wherein the thickness of the outer layer is greater than the thickness of the inner layer in the body portion. The multilayer preform according to claim 1, wherein the thickness of the outer layer in the body portion is 0.3 to 25 times the thickness of the inner layer. The multilayer preform according to any one of claims 1 to 3, wherein the thickness of the inner layer in the body is 0.1 mm or more and 2.9 mm or less. The multilayer preform according to any one of claims 1 to 4, wherein the inner surface of the outer layer is entirely covered by the inner layer. A method for producing a multi-layer preform having a mouth portion, a body portion, and a bottom portion, comprising the steps of:
A step of preparing a mold assembly having a cavity side mold and a core side mold including a core;
A step of attaching a sheet molded body or a film to the core of the core side mold;
Inserting the core to which the sheet molded body or the film is attached into the cavity side mold;
and forming a multi-layer preform having an inner layer constituted by the sheet molded body or the film, and an outer layer disposed outside the inner layer and integrally formed with the inner layer, by injecting an injection resin into a space between the cavity-side mold and the sheet molded body or the film attached to the core,
The inner layer is made of virgin polyester,
The outer layer is made of recycled polyester,
The content of the virgin polyester is 60 parts by mass or more and 90 parts by mass or less with respect to 100 parts by mass of a total amount of the resin material contained in the inner layer,
The content of the recycled polyester is 60 parts by mass or more and 90 parts by mass or less with respect to 100 parts by mass of a total amount of the resin material contained in the outer layer,
The inner layer does not contain mechanically recycled polyester,
A method for producing a multilayer preform , wherein a thickness of the inner layer in the body portion and a thickness of the inner layer in the bottom portion are each greater than a thickness of the inner layer in the mouth portion . A step of producing a multi-layer preform by the method for producing a multi-layer preform according to claim 6;
and a step of blow molding the multilayer preform.