Preform, plastic bottle, and method for manufacturing plastic bottle

Abstract

To provide a preform, a plastic bottle and a manufacturing method of plastic bottle that can reduce environmental impact by plastic bottles.SOLUTION: A preform 23 includes a mouth part 26, a body part 27 and a bottom part 28 . The body part 27 has a neck part 27a, a body middle part 27b, and a reduced diameter part 27c. The neck part 27a, the body middle part 27b and reduced diameter part 27c include an outer layer 25 comprising mechanically recycled polyester. The body middle part 27b and reduced diameter part 27c are positioned inside the outer layer 25 and include an inner layer 24 comprising virgin polyester, biomass-derived polyester, or chemically recycled polyester. In at least a portion of the reduced diameter part 27c, the thickness of the inner layer 24 gradually decreases from the body middle part 27b side toward the neck part 27a side.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to preforms, plastic bottles, and methods for manufacturing plastic bottles. [Background technology]

[0002] Polyesters such as polyethylene terephthalate are inexpensive and have excellent mechanical properties, chemical stability, heat resistance, gas barrier properties, transparency, etc., and are therefore widely used in the manufacture of containers for filling beverages, etc. Such containers are obtained by preparing a polyester preform and then blow molding the preform.

[0003] In recent years, polyesters recycled by various methods have been used to manufacture containers in order to reduce the environmental impact (for example, Patent Document 1). Containers and preforms used to manufacture containers are sometimes manufactured by combining recycled materials with non-recycled materials. Patent Document 1 discloses the manufacture of preforms by combining virgin polyester and recycled polyester. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 7-178801 Summary of the Invention [Problem to be solved by the invention]

[0005] There is a demand for further reduction in the environmental impact of containers. Specifically, when containers are manufactured by combining recycled and non-recycled materials, there is a demand for a larger ratio of recycled materials to non-recycled materials.

[0006] The present disclosure has been made in consideration of these points, and aims to provide a preform, a plastic bottle, and a method for manufacturing a plastic bottle that can reduce the environmental impact of plastic bottles. [Means for solving the problem]

[0007] A preform according to one embodiment comprises a mouth portion having a support ring, a body portion connected to the mouth portion, and a bottom portion connected to the body portion, wherein the body portion has a neck portion located on the support ring side, a mid-body portion located on the bottom side, and a tapered portion located between the neck portion and the mid-body portion and tapering in diameter from the neck side toward the mid-body portion, wherein the neck portion, the mid-body portion, and the tapered portion of the body portion comprise outer layers containing mechanically recycled polyester, and the mid-body portion and the tapered portion are located inside the outer layer and comprise inner layers containing virgin polyester, biomass-derived polyester, or chemically recycled polyester, and in at least a portion of the tapered portion, the thickness of the inner layer gradually decreases from the mid-body portion side toward the neck portion side.

[0008] In the preform according to one embodiment, the upper end of the inner layer may be spaced apart from the support ring by 0 mm or more and 9 mm or less.

[0009] In one embodiment of the preform, when the distance from the upper end of the inner layer is X and the thickness of the inner layer of the reduced diameter portion at the position where the distance from the upper end of the inner layer is X is Y, 0.0166×X≦Y≦2.5875×X The following relationship may be established.

[0010] In one embodiment of the preform, the thickness of the thickest part of the outer layer in the middle trunk portion may be 100% or more and 110% or less of the thickness of the thinnest part of the outer layer.

[0011] In one embodiment of the preform, the thickness of the thickest part of the inner layer in the central trunk portion may be 100% or more and 110% or less of the thickness of the thinnest part of the inner layer.

[0012] In the preform according to one embodiment, the thickness of the outer layer in the center trunk portion may be 0.25 to 4.0 times the thickness of the inner layer.

[0013] In the preform according to one embodiment, the L of the mouth * a * b * Lightness L in the color system * The value of L of the center of the trunk is 70.0 or more and 86.5 or less. * a * b * Lightness L in the color system * The value of may be greater than or equal to 86.6 and less than or equal to 94.0.

[0014] A plastic bottle according to one embodiment comprises a mouth portion having a support ring, a neck portion connected to the mouth portion, a shoulder portion connected to the neck portion, a body portion connected to the shoulder portion, and a bottom portion connected to the body portion, wherein the shoulder portion and the body portion comprise an outer layer having mechanically recycled polyester, the body portion is located inside the outer layer and comprises an inner layer having virgin polyester, biomass-derived polyester, or chemically recycled polyester, and in at least a portion of the shoulder portion, the thickness of the inner layer gradually decreases from the body side toward the mouth side.

[0015] A method for manufacturing a plastic bottle according to one embodiment includes the steps of preparing a preform according to one embodiment, heating the preform, and biaxially stretching and blow molding the preform. [Effects of the Invention]

[0016] According to the present disclosure, the environmental impact of plastic bottles can be reduced. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a partial vertical cross-sectional view showing a plastic bottle according to one embodiment. [Figure 2] FIG. 2 is a vertical cross-sectional view showing a preform according to one embodiment. [Figure 3] FIG. 3 is a diagram illustrating a method for manufacturing a preform according to one embodiment. [Figure 4] FIG. 4 is a diagram illustrating a method for manufacturing a preform according to one embodiment. [Figure 5] FIG. 5 is a diagram illustrating a method for manufacturing a preform according to one embodiment. [Figure 6] FIG. 6 is a diagram showing a method for manufacturing a preform according to one embodiment. [Figure 7] FIG. 7 is a diagram illustrating a method for manufacturing a preform according to one embodiment. [Figure 8] 8(a)-(d) are diagrams showing a method for manufacturing a plastic bottle according to one embodiment. [Figure 9] FIG. 9 is a partial vertical cross-sectional view showing a modified example of the plastic bottle according to the embodiment. [Figure 10] FIG. 10 is a vertical cross-sectional view showing a modified example of the preform according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0018] An embodiment will now be described with reference to the drawings. FIGS. 1 to 8 are diagrams illustrating one embodiment. The following figures are schematic diagrams. Therefore, the size and shape of each part are appropriately exaggerated for ease of understanding. Furthermore, appropriate modifications can be made without departing from the technical concept. In the following figures, identical parts are denoted by the same reference numerals, and some detailed descriptions may be omitted. Furthermore, the numerical values, such as dimensions, and material names of each component described in this specification are examples of an embodiment and are not limited to these and may be selected and used as appropriate. In this specification, terms specifying shapes or geometric conditions, such as parallel, orthogonal, and perpendicular, are interpreted not only strictly but also to include substantially the same state.

[0019] <Plastic bottles and preforms> First, a plastic bottle 10 manufactured from a preform 23 according to this embodiment and the preform 23 according to this embodiment will be described with reference to Figures 1 and 2. In this specification, "above" refers to the upper side when the plastic bottle 10 and the preform 23 are held upright (Figures 1 and 2). In this specification, "below" refers to the lower side when the plastic bottle 10 and the preform 23 are held upright.

[0020] (Plastic bottle) First, a plastic bottle 10 will be described with reference to Figure 1. The plastic bottle 10 is a container obtained by subjecting a preform 23 to blow molding.

[0021] In this embodiment, plastic bottle 10 includes a mouth 13, a neck 14 connected to mouth 13, a shoulder 15 connected to neck 14, a body 16 connected to shoulder 15, and a bottom 17 connected to body 16. Mouth 13 includes a threaded portion 13a onto which a cap (not shown) is screwed, a cap 13b provided below threaded portion 13a, and a support ring 13c provided below cap 13b. Contents, such as liquid, are filled into plastic bottle 10 through mouth 13, and a cap (not shown) is screwed onto mouth 13 to produce a plastic bottle filled with the contents. Note that mouth 13 may have a conventionally known shape.

[0022] The neck portion 14 is located between the support ring 13c and the shoulder portion 15, and has a generally cylindrical shape with a generally uniform diameter.

[0023] The shoulder portion 15 is provided between the neck portion 14 and the body portion 16, and has a shape in which the outer diameter gradually increases downward.

[0024] The body 16 has a cylindrical shape with a generally uniform diameter overall. However, the shape of the body 16 is not limited to this. The body 16 may have a polygonal cylindrical shape, such as a rectangular or octagonal cylindrical shape. The body 16 may have a cylindrical shape with a non-uniform horizontal cross section from top to bottom. The outer surface of the body 16 may have irregularities, such as vacuum absorption panels or grooves.

[0025] Bottom 17 has a centrally located depression 20 and a ground contact portion 21 provided around depression 20. This configuration can prevent deformation of plastic bottle 10 due to increases or decreases in internal pressure when heated contents are filled into plastic bottle 10 or when the contents are heated after filling. The shape of bottom 17 is not particularly limited, and may have any conventionally known bottom shape (for example, a petaloid bottom or a rounded bottom).

[0026] The volume / weight of such a plastic bottle 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. Having a volume / weight of 5 mL / g or more improves the blow moldability of the plastic bottle 10. Having a volume / weight of 50 mL / g or less improves the heat resistance and strength of the plastic bottle 10. Typically, the plastic bottle 10 is filled with an amount of content that fits below the bottom of the support ring 13c when the plastic bottle 10 is upright. The top of the content (or the liquid level if the content is liquid) may be located at the neck 14 or shoulder 15.

[0027] 1, a plastic bottle 10 is provided with an inner layer 11 and an outer layer 12 disposed on the outside of the inner layer 11. The inner layer 11 and the outer layer 12 are integrally formed with each other.

[0028] (Inner layer of plastic bottle) Next, the inner layer 11 of the plastic bottle 10 will be described. The body 16 of the plastic bottle 10 includes the inner layer 11. In the example shown in FIG. 1, the shoulder 15, body 16, and bottom 17 of the plastic bottle 10 include the inner layer 11. As shown in FIG. 1, the inner layer 11 extends from a position below the lower end of the support ring 13c of the mouth 13 to the bottom 17. In the example shown in FIG. 1, the inner layer 11 extends from a position below the upper end of the shoulder 15 (the lower end of the neck 14) to the bottom 17. The vertical distance Ha from the upper end of the inner layer 11 to the lower end of the support ring 13c may be 0 mm or more and 30 mm or less. The inner layer 11 is preferably provided continuously from the upper end of the shoulder 15 to the bottom 17. Although not shown, the inner layer 11 may extend from the neck 14 to the bottom 17. The inner layer 11 covers a portion of the inner surface of the outer layer 12. The inner layer 11 is not provided above the lower end of the support ring 13c of the mouth portion 13. In Fig. 1, the inner layer 11 is not provided on the mouth portion 13 or the neck portion 14, but is provided on a part of the shoulder portion 15 and on the entire body portion 16 and the bottom portion 17.

[0029] The effects of this configuration are explained below. If the outer layer 12, made of mechanically recycled polyester (described below), comes into contact with the contents of the plastic bottle 10, there is concern that the catalyst used to polymerize the polyester and any remaining contaminants that have not been removed may leach into the contents. Furthermore, in convenience stores and other locations, containers filled with contents are typically placed upright and heated in a hot water heater before being sold. The leaching of the catalyst is particularly problematic in such a heated state. As described above, the plastic bottle 10 is typically filled with an amount of contents that fits below the bottom of the support ring 13c when the plastic bottle 10 is held upright. Therefore, the portion of the plastic bottle 10 that is below the bottom of the support ring 13c is more likely to be in contact with the contents for a longer period of time than the portion that is above the bottom of the support ring 13c.

[0030] By providing the inner layer 11 from a position below the lower end of the support ring 13c to the bottom 17, the inner layer 11 can be positioned in a region of the inner surface of the plastic bottle 10 that is likely to come into contact with the contents for a long time when the plastic bottle 10 is held upright. Therefore, even when the mechanically recycled polyester described below is used for the outer layer 12, the elution of a catalyst (e.g., antimony) into the contents can be effectively suppressed. Furthermore, by not providing the inner layer 11 above the lower end of the support ring 13c of the mouth 13, it is possible to avoid providing the inner layer 11 in a region that is unlikely to come into contact with the contents for a long time. Therefore, the ratio of the amount of mechanically recycled polyester used for the outer layer 12 to the amount of virgin polyester or the like used for the inner layer 11 described below can be increased.

[0031] The inner layer 11 contains virgin polyester, biomass-derived polyester, or chemically recycled polyester (hereinafter, simply referred to as virgin polyester, etc.). This configuration can prevent catalyst (e.g., antimony) from leaching into the contents, even when mechanically recycled polyester is used for the outer layer 12, as described below. Herein, "virgin polyester" refers to polyester that has not been recycled, i.e., unused polyester. Also, "biomass-derived polyester" refers to polyester obtained from raw materials containing biomass-derived monomers. Also, "chemically recycled polyester" refers to polyester obtained by decomposing a polyester container down to the monomer level and repolymerizing it.

[0032] As an example, the biomass content of "biomass-derived polyester" is 3% or more. "Biomass content" is a value measured by radiocarbon (C14) analysis to determine the amount of carbon derived from biomass. Carbon dioxide in the atmosphere contains a certain percentage of C14 (105.5 pMC). For this reason, it is known that the C14 content in plants that grow by absorbing carbon dioxide from the atmosphere, such as corn, is also about 105.5 pMC. It is also known that fossil fuels contain very little C14. Therefore, the percentage of carbon derived from biomass can be calculated by measuring the percentage of C14 in the total carbon atoms in the polyester.

[0033] For example, the content of C14 in polyester is P C14 The content of biomass-derived carbon in this case is P bio is calculated as follows: P bio (%)=P C14 / 105.5×100

[0034] In the inner layer 11, the content of virgin polyester or the like 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 resin materials contained in the inner layer 11. Having a virgin polyester or the like content of 20 parts by mass or more can improve the adhesion between the inner layer 11 and the outer layer 12 containing mechanically recycled polyester, as described below, and can suppress delamination between the inner layer 11 and the outer layer 12. Having a virgin polyester or the like content of 60 parts by mass or more can further improve the adhesion between the outer layer 12 containing mechanically recycled polyester and the inner layer 11, and can more effectively suppress delamination between the inner layer 11 and the outer layer 12. Furthermore, having a virgin polyester or the like content of 90 parts by mass or less can improve the dispersion efficiency of a resin having a function such as barrier property, for example, when blended with virgin polyester or the like. It is preferable that the inner layer 11 does not contain a mechanical polyester, as described below. This improves the hygiene of the plastic bottle 10.

[0035] When the inner layer 11 includes virgin polyester, the virgin polyester may be selected from antimony-catalyzed polyester, manganese-catalyzed polyester, titanium-catalyzed polyester, aluminum-catalyzed polyester, lithium-catalyzed polyester, and germanium-catalyzed polyester. For example, antimony-catalyzed polyester herein refers to polyester produced using an antimony catalyst as a polymerization catalyst. Therefore, the polyesters listed above refer to polyesters produced using the respective catalysts as polymerization catalysts.

[0036] Examples of antimony catalysts include antimony trioxide, antimony pentoxide, antimony acetate, triphenylantimony, and antimony glycol.

[0037] Examples of the manganese catalyst include fatty acid manganese salts such as manganese acetate, manganese carbonate, manganese chloride, manganese acetylacetonate salts, and manganese hydroxide.

[0038] 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, titanate-aluminum hydroxide mixtures, titanium chloride, titanium chloride-aluminum chloride mixtures, titanium bromide, titanium fluoride, potassium hexafluorotitanate, cobalt hexafluorotitanate, manganese hexafluorotitanate, ammonium hexafluorotitanate, and titanium acetylacetonate.

[0039] Examples of aluminum catalysts include aluminum trisacetylacetate, aluminum monoacetylacetonate bis(ethylacetoacetate), and ethylacetoacetate aluminum diisopropylate.

[0040] Examples of the lithium catalyst include ethyllithium, propyllithium, n-butyllithium, sec-butyllithium, tert-butyllithium, and phenyllithium.

[0041] Examples of germanium catalysts include germanium dioxide, germanium tetroxide, germanium tetramethoxide, germanium tetraethoxide, germanium tetrapropoxide, germanium tetrabutoxide, germanium tetrapentoxide, and germanium tetrahexoxide.

[0042] In this embodiment, the term "polyester" refers to a copolymer of a dicarboxylic acid compound and a diol compound.

[0043] 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.

[0044] 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-methyl-1,3-propanediol ... -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.

[0045] Among polyesters, polyethylene terephthalate, which is a copolymer of terephthalic acid and ethylene glycol, or modified polyethylene terephthalate in which a copolymerization monomer is added to this is preferred.

[0046] The polyester may be biomass-derived polyethylene terephthalate or fossil fuel-derived polyethylene terephthalate. The biomass-derived polyethylene terephthalate may be polyethylene terephthalate in which the dicarboxylic acid compound is terephthalic acid derived from fossil fuel and the diol compound is ethylene glycol derived from biomass. In this way, by including biomass-derived polyethylene terephthalate in inner layer 11, the environmental impact of plastic bottle 10 can be further reduced.

[0047] The polyester may contain a monomer other than the dicarboxylic acid compound and the diol compound as long as the properties of the present embodiment are not impaired. In this case, the content of such a monomer is preferably 10 mol % or less, more preferably 5 mol % or less, and even more preferably 3 mol % or less, based on the total structural units.

[0048] The inner layer 11 may contain additives as long as they do not impair the properties of the present embodiment. Examples of additives include 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, deodorizers, 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.

[0049] 1, the thickness T1 (radial distance) of the inner layer 11 in the shoulder portion 15 gradually decreases from the lower end side to the upper end side of the shoulder portion 15 in at least a part of the shoulder portion 15. As an example, in the body portion 16, the thickness of the thickest part of the inner layer 11 (radial distance) is 100% or more and 150% or less, preferably 100% or more and 130% or less, of the thinnest part of the inner layer 11. The thickness of the inner layer 11 in the body portion 16 may vary in the up-down direction.

[0050] The thickness (radial distance) of the inner layer 11 of the plastic bottle 10 is preferably 0.02 mm or more and 0.48 mm or less, and more preferably 0.05 mm or more and 0.4 mm or less, in any region of the body 16 of the plastic bottle 10. By making the thickness of the inner layer 11 0.02 mm or more, even if mechanically recycled polyester is used for the outer layer 12, exposure of the mechanically recycled polyester contained in the outer layer 12 from the inner surface of the inner layer 11 can be effectively prevented. This effectively prevents elution of catalysts (e.g., antimony) into the contents of the plastic bottle 10. Furthermore, by making the thickness of the inner layer 11 0.48 mm or less, the proportion of the outer layer 12 in the plastic bottle 10 can be increased, thereby reducing the environmental impact of the plastic bottle 10.

[0051] (Outer layer of plastic bottle) Next, the outer layer 12 of the plastic bottle 10 will be described. The shoulder 15 and body 16 of the plastic bottle 10 include the outer layer 12. In the example shown in FIG. 1, the mouth 13, shoulder 15, body 16, and bottom 17 include the outer layer 12. As shown in FIG. 1, the outer layer 12 extends from the upper end of the mouth 13 to the bottom 17. The presence of the outer layer 12 also in the mouth 13 of the plastic bottle 10 allows the plastic bottle 10 to use a larger amount of mechanically recycled polyester (described below) relative to the amount of virgin polyester, etc. used. This further reduces the environmental impact of the plastic bottle 10. As described above, a portion of the inner surface of the outer layer 12 is covered by the inner layer 11. That is, the inner surface of the outer layer 12 is covered by the inner layer 11 from a position below the lower end of the support ring 13c of the mouth 13 to the bottom 17. The inner layer 11 is not provided above the lower end of the support ring 13c of the mouth 13. Therefore, above the lower end of the support ring 13 c of the mouth portion 13 , the inner surface of the outer layer 12 is not covered with the inner layer 11 .

[0052] The outer layer 12 contains mechanically recycled polyester. This configuration reduces the environmental impact of the plastic bottle 10 of this embodiment. In this specification, "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 at high temperature and reduced pressure to remove contaminants from within the resin. Mechanically recycled polyester may contain two or more catalysts. In this case, the mechanically recycled polyester may contain, for example, two or more of antimony-catalyzed polyester, manganese-catalyzed polyester, titanium-catalyzed polyester, aluminum-catalyzed polyester, lithium-catalyzed polyester, and germanium-catalyzed polyester.

[0053] The mechanically recycled polyester is, for example, mechanically recycled polyethylene terephthalate. For example, the mechanically recycled polyethylene terephthalate contains antimony at a concentration of 20 mg / L or more and 54 mg / L or less, preferably 25 mg / L or more and 50 mg / L or less. For another example, the mechanically recycled polyethylene terephthalate contains sodium at a concentration of 12 mg / L or more, preferably 14 mg / L or more. Alternatively, the mechanically recycled polyethylene terephthalate contains calcium at a concentration of 4 mg / L or more, preferably 4.5 mg / L or more. Alternatively, the mechanically recycled polyethylene terephthalate contains magnesium at a concentration of 2.5 mg / L or more, preferably 3.0 mg / L or more.

[0054] In the outer layer 12, the content of the mechanically 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 resin materials contained in the outer layer 12. When the content of the mechanically recycled polyester is 20 parts by mass or more, the environmental impact of the plastic bottle 10 can be further reduced. Furthermore, when the content of the mechanically recycled polyester is 60 parts by mass or more, the environmental impact of the plastic bottle 10 can be further reduced. Furthermore, when the content of the mechanically recycled polyester is 90 parts by mass or less, for example, when a resin having a function such as barrier property is blended with the mechanically recycled polyester, the dispersion efficiency of the resin in the outer layer 12 can be improved.

[0055] Furthermore, the content of the mechanically recycled polyester in the plastic bottle 10 is preferably 40 parts by mass or more and 90 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 resin material contained in the plastic bottle 10. When the content of the mechanically recycled polyester is 40 parts by mass or more, relative to 100 parts by mass of the total amount of resin material contained in the plastic bottle 10, the environmental impact of the plastic bottle 10 can be further reduced. When the content of the mechanically recycled polyester is 90 parts by mass or less, relative to 100 parts by mass of the total amount of resin material contained in the plastic bottle 10, the mechanically recycled polyester contained in the outer layer 12 in the plastic bottle 10 can be prevented from being exposed from the inner surface of the inner layer 11.

[0056] Furthermore, the eluted antimony concentration of the plastic bottle 10 is preferably less than 6 ppb, and more preferably less than 3 ppb. An eluted antimony concentration of less than 6 ppb satisfies the value recommended by the U.S. Food and Drug Administration (FDA) under 21 CFR (Chapter 21 of the Code of Federal Regulations). Depending on the type of contents filled into the plastic bottle 10, the contents may already contain trace amounts of antimony. Having an eluted antimony concentration of less than 3 ppb in the plastic bottle 10 reduces the amount of antimony ultimately dissolved in the contents. In this embodiment, the "eluted antimony concentration of the plastic bottle" refers to the concentration of antimony contained in the water removed from the plastic bottle 10 after filling the plastic bottle 10 with ultrapure water at 23°C, placing the water-filled plastic bottle 10 on its side, and leaving it in an inverted position at 70°C for 14 days.

[0057] The outer layer 12 may contain additives as long as they do not impair the properties of the present embodiment. Examples of additives include 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, deodorizers, 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.

[0058] The thickness (radial distance) of the outer layer 12 of the plastic bottle 10 is preferably 0.02 mm or more and 0.48 mm or less, and more preferably 0.05 mm or more and 0.4 mm or less, in any region of the body 16 of the plastic bottle 10. Having a thickness of the outer layer 12 of 0.02 mm or more allows for a greater proportion of the outer layer 12 in the plastic bottle 10, further reducing the environmental impact of the plastic bottle 10. Furthermore, having a thickness of the outer layer 12 of 0.48 mm or less allows for a thinner plastic bottle 10.

[0059] Such plastic bottle 10 can prevent antimony and other substances from eluting into the contents, even when the plastic bottle 10 is filled with high-temperature contents or when the contents are heated after filling. For this reason, plastic bottle 10 can be suitably used as a heating container.

[0060] The plastic bottle 10 according to the present disclosure may further include a vapor-deposited film (not shown) located on the inner surface of the inner layer 11. This can improve the gas barrier properties of the plastic bottle 10.

[0061] Examples of the vapor-deposited film 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.

[0062] The hard carbon film made of DLC is also called i-carbon film or hydrogenated amorphous carbon film (aC:H), and is an amorphous carbon film mainly composed of SP3 bonds.

[0063] The thickness of the vapor-deposited film is not particularly limited, and may be, for example, 1 nm or more and 150 nm or less.

[0064] The vapor deposition film can be formed by a conventionally known method, for example, physical vapor deposition methods (PVD methods) such as vacuum deposition, sputtering, and ion plating, and chemical vapor deposition methods (CVD methods) such as plasma chemical vapor deposition, thermal chemical vapor deposition, and photochemical vapor deposition.

[0065] (preform) Next, the preform 23 will be described with reference to Figure 2. The preform 23 is a member used to manufacture the plastic bottle 10.

[0066] In this embodiment, the preform 23 includes a mouth portion 26 having a support ring 26 a , a body portion 27 connected to the mouth portion 26 , and a bottom portion 28 connected to the body portion 27 .

[0067] Of these, mouth portion 26 corresponds to mouth portion 13 of plastic bottle 10 described above, and has substantially the same shape as mouth portion 13. That is, mouth portion 26 has thread portion 26b, a turnip 26c provided below thread portion 26b, and the above-mentioned support ring 26a provided below turnip 26c. Thread portion 26b of preform 23 corresponds to thread portion 13a of plastic bottle 10, and has substantially the same shape as thread portion 13a. Turnip 26c of preform 23 corresponds to turnip 13b of plastic bottle 10, and has substantially the same shape as turnip 13b. Support ring 26a of preform 23 corresponds to support ring 13c of plastic bottle 10, and has substantially the same shape as support ring 13c.

[0068] The body 27 corresponds to the neck 14, shoulder 15, and body 16 of the plastic bottle 10 described above. The body 27 is connected to the mouth 26 and extends downward from the mouth 26. The horizontal cross section of the body 27 is circular at any point from its upper end to its lower end. However, the shape is not limited to this, and the body 27 may have a cylindrical shape such as an elliptical cylindrical shape or a polygonal cylindrical shape such as a rectangular cylindrical shape.

[0069] This body 27 has a neck portion 27a located on the support ring 26a side, a middle body portion 27b located on the bottom 28 side, and a tapered portion 27c located between the neck portion 27a and the middle body portion 27b and tapering in diameter from the neck portion 27a side toward the middle body portion 27b side.

[0070] Of these, neck portion 27a is the part of body portion 27 with the largest outer diameter and has a cylindrical shape with a substantially uniform outer diameter. The thickness (radial distance) of neck portion 27a is substantially constant overall. The height H1 (vertical distance) of neck portion 27a is preferably 1 mm or more and 5 mm or less. Furthermore, the outer diameter D1 of neck portion 27a is preferably 24.5 mm or more and 26 mm or less.

[0071] The diameter-reducing portion 27c has a shape in which the outer diameter gradually decreases downward. The thickness (radial distance) of the diameter-reducing portion 27c gradually increases downward. The height H2 (vertical distance) of the diameter-reducing portion 27c is preferably 8 mm or more and 17 mm or less.

[0072] The central trunk portion 27b is the portion of the trunk portion 27 with the smallest outer diameter and has a cylindrical shape with a substantially uniform outer diameter. The thickness (radial distance) of the central trunk portion 27b is substantially constant overall. The height H3 (vertical distance) of the central trunk portion 27b is preferably 25 mm or more and 77 mm or less. The outer diameter D2 of the central trunk portion 27b is preferably 17 mm or more and 25.5 mm or less.

[0073] The bottom 28 corresponds to the bottom 17 of the plastic bottle 10 and has a generally hemispherical shape. A gate mark 28a is formed on the bottom 28. In this specification, the term "gate mark" refers to a mark such as a concavo-convex shape formed by the gates 74, 76 (see FIGS. 3 and 6) used to inject the injection resin when the inner layer 24 or the outer layer 25 is produced by injection molding.

[0074] The mouth 26, body 27, and bottom 28 of the preform 23 are integrally formed. The total height H of the body 27 and bottom 28 (the vertical distance from the lower end of the support ring 26a to the lower surface of the gate mark 28a) is preferably 60 mm or more and 130 mm or less.

[0075] 2, the preform 23 is provided with an inner layer 24 and an outer layer 25 disposed on the outer side of the inner layer 24. The inner layer 24 and the outer layer 25 are integrally formed with each other.

[0076] (inner layer of preform) Next, the inner layer 24 of the preform 23 will be described. As shown in Fig. 2, the central trunk portion 27b and the reduced diameter portion 27c of the trunk portion 27 of the preform 23 include the inner layer 24. In the example shown in Fig. 2, the central trunk portion 27b and the reduced diameter portion 27c of the trunk portion 27, as well as the bottom portion 28, include the inner layer 24. The inner layer 24 is located inside the outer layer 25, which will be described later. The inner layer 24 included in the central trunk portion 27b and the inner layer 24 included in the reduced diameter portion 27c are continuous. The inner layer 24 included in the trunk portion 27 and the inner layer 24 included in the bottom portion 28 are continuous.

[0077] The inner layer 24 is provided from a position below the lower end of the support ring 26a of the mouth portion 26 to the bottom portion 28. The inner layer 24 is provided from a position below the upper end of the reduced diameter portion 27c (the lower end of the neck portion 27a) to the bottom portion 28. The inner layer 24 is preferably provided continuously from the upper end of the central portion 27b to the bottom portion 28. Although not shown, the inner layer 24 may be provided from the neck portion 27a to the bottom portion 28 of the body portion 27. The inner layer 24 covers a portion of the inner surface of the outer layer 25. The inner layer 24 is not provided above the lower end of the support ring 26a of the mouth portion 26. In FIG. 2, the inner layer 24 is not provided on the mouth portion 26 and the neck portion 27a, but is provided on a portion of the reduced diameter portion 27c and over the entire central portion 27b and bottom portion 28.

[0078] The upper end of the inner layer 24 may be spaced from the support ring 26a by 0 mm or more and 9 mm or less. In other words, the vertical distance H5 from the lower end of the support ring 26a to the upper end of the inner layer 24 may be 0 mm or more and 9 mm or less.

[0079] The inner layer 24 also includes a gate mark 24b provided at its lower end. This gate mark 24b, together with the gate mark 25a of the outer layer 25, constitutes the gate mark 28a described above. This gate mark 24b is covered by the gate mark 25a of the outer layer 25.

[0080] The material constituting the inner layer 24 is the same as the material constituting the inner layer 11 of the plastic bottle 10. That is, the inner layer 24 of the preform 23 contains virgin polyester, biomass-derived polyester, or chemically recycled polyester.

[0081] 2, in at least a portion of the reduced diameter portion 27c, the thickness y (radial distance) of the inner layer 24 of the reduced diameter portion 27c gradually decreases from the middle barrel portion 27b toward the neck portion 27a. This prevents the flow of injected resin from being obstructed in the region of the reduced diameter portion 27c where the inner layer 24 is to be formed when the inner layer 24 is produced by injection molding, as described below. This makes it easier for the injected resin to spread throughout the entire region where the inner layer 24 is to be formed when the inner layer 24 is produced by injection molding. As a result, it is possible to prevent the occurrence of so-called short shots, in which the injected resin does not spread throughout the entire region where the inner layer 24 is to be formed.

[0082] In the preform 23, the thickness y of the inner layer 24 of the reduced diameter portion 27c gradually decreases from the middle portion 27b toward the neck portion 27a. As a result, the thickness T1 of the inner layer 11 of the shoulder portion 15 of the plastic bottle 10 produced from the preform 23 gradually decreases from the lower end toward the upper end of the shoulder portion 15 in at least a portion of the shoulder portion 15.

[0083] 2, the distance (vertical distance) from the upper end of the inner layer 24 is defined as X. Furthermore, the thickness (radial distance) of the inner layer 24 at the position where the distance from the upper end of the inner layer 24 to the reduced diameter portion 27c is X is defined as Y. In this case, the relationship 0.0166×X≦Y≦2.5875×X may hold.

[0084] Furthermore, in the central trunk portion 27b, the thickness of the portion of the inner layer 24 where the thickness T3 is the thickest is 100% to 110%, preferably 100% to 105%, of the thickness of the portion of the inner layer 24 where the thickness T3 is the thinnest. This prevents the flow of injected resin from being obstructed in the region of the central trunk portion 27b where the inner layer 24 is to be formed when the inner layer 24 is produced by injection molding. This prevents the occurrence of so-called short shots.

[0085] The thickness T3 of the inner layer 24 at the center body portion 27b of the preform 23 is preferably 0.3 mm or more and 3.2 mm or less, and more preferably 0.4 mm or more and 3.0 mm or less. Having the thickness T3 of the inner layer 24 of 0.3 mm or more prevents the mechanically recycled polyester contained in the outer layer 12 from being exposed from the inner surface of the inner layer 11 in the plastic bottle 10 produced from the preform 23, even when the outer layer 25 is made of mechanically recycled polyester. This effectively prevents the elution of a catalyst (e.g., antimony) into the contents of the plastic bottle 10. Furthermore, having the thickness T3 of the inner layer 24 of 0.3 mm or more allows the injected resin to more smoothly spread throughout the entire region where the inner layer 24 is to be formed when the inner layer 24 is produced by injection molding, effectively preventing the occurrence of so-called short shots. Furthermore, by setting the thickness T3 of the inner layer 24 to 3.2 mm or less, the proportion of the outer layer 12 in the plastic bottle 10 produced from the preform 23 can be increased, and the environmental impact of the plastic bottle 10 can be further reduced.

[0086] The inner layer 24 of such a preform 23 is a layer produced by injection molding synthetic resin pellets.

[0087] (Outer layer of the preform) Next, the outer layer 25 of the preform 23 will be described. As shown in Fig. 2, the neck portion 27a, the central portion 27b, and the reduced diameter portion 27c of the body portion 27 of the preform 23 include the outer layer 25. In the example shown in Fig. 2, the outer layer 25 is disposed over the entire area of ​​the preform 23 in the vertical direction. That is, the outer layer 25 is disposed in the mouth portion 26, the body portion 27 (neck portion 27a, central portion 27b, and reduced diameter portion 27c), and the bottom portion 28. The outer layer 25 included in the neck portion 27a, the outer layer 25 included in the central portion 27b, and the outer layer 25 included in the reduced diameter portion 27c are continuous. The outer layer 25 included in the mouth portion 26, the outer layer 25 included in the body portion 27, and the outer layer 25 included in the bottom portion 28 are continuous.

[0088] The outer layer 25 is provided from the upper end of the mouth 26 to the lower end of the bottom 28. In this way, the presence of the outer layer 25 also in the mouth 26 of the preform 23 makes it possible to increase the amount of mechanically recycled polyester used in the preform 23 relative to the amount of virgin polyester, etc. used. This further reduces the environmental impact of the plastic bottle 10 produced from the preform 23. As described above, the inner surface of the outer layer 25 is covered with the inner layer 24 from a position below the lower end of the support ring 26a of the mouth 26 to the bottom 28.

[0089] The outer layer 25 also includes a gate mark 25a provided at its lower end. As described above, the gate mark 25a of the outer layer 25, together with the gate mark 24b of the inner layer 24, constitutes the gate mark 28a described above and covers the gate mark 24b of the inner layer 24. In this case, a gate 76 (see FIG. 6 ) of a second-cavity mold 75 (described later) for forming the outer layer 25 is larger than a gate 74 (see FIG. 3 ) of a first-cavity mold 71 (described later) for forming the inner layer 24. Therefore, as described later, when the outer layer 25 is formed by injecting an injection resin onto the outer surface of the inner layer 24, the flow of the injection resin constituting the outer layer 25 can be prevented from being obstructed by the gate mark 24b of the inner layer 24. In this case, the outer diameter D3 of the gate mark 24b of the inner layer 24 may be 3.0 mm or more and 3.4 mm or less, and the outer diameter D4 of the gate mark 25a of the outer layer 25 may be 3.5 mm or more and 4.0 mm or less.

[0090] The material constituting the outer layer 25 is the same as the material constituting the outer layer 12 of the plastic bottle 10. That is, the outer layer 25 of the preform 23 comprises mechanically recycled polyester.

[0091] The thickness (radial distance) of the outer layer 25 of such a preform 23 is preferably greater than the thickness (radial distance) of the inner layer 24 in any region where the outer layer 25 is provided. This allows the amount of mechanically recycled polyester used in the preform 23 to be increased relative to the amount of virgin polyester, etc. used. This further reduces the environmental impact of the plastic bottle 10 produced from the preform 23.

[0092] The outer layer 25 is configured so that its thickness (t1 to t3 (radial distance)) varies in the trunk portion 27 of the preform 23. In the neck portion 27a of the trunk portion 27, the thickness t1 of the outer layer 25 is generally constant overall. In the mid-torso portion 27b of the trunk portion 27, the thickness t3 of the outer layer 25 is generally constant overall. On the other hand, in the reduced diameter portion 27c, the thickness t2 of the outer layer 25 gradually increases downward. The thicknesses t1 to t3 of the outer layer 25 increase in the order of thickness t1 in the neck portion 27a, thickness t2 in the reduced diameter portion 27c, and thickness t3 in the mid-torso portion 27b.

[0093] Here, in the reduced diameter portion 27c, the thickness t2 of the outer layer 25 is 0.19 to 4.0 times the thickness T2 of the inner layer 24 (the maximum thickness in the reduced diameter portion 27c). In particular, when the thickness t3 of the outer layer 25 in the middle trunk portion 27b is 4.0 times the thickness T3 of the inner layer 24, the thickness t2 of the outer layer 25 in the reduced diameter portion 27c may be 3.0 to 4.0 times the thickness T2 of the inner layer 24 (the maximum thickness in the reduced diameter portion 27c). Furthermore, when the thickness t3 of the outer layer 25 in the middle trunk portion 27b is 0.25 times the thickness T3 of the inner layer 24, the thickness t2 of the outer layer 25 in the reduced diameter portion 27c may be 0.19 to 0.25 times the thickness T2 of the inner layer 24 (the maximum thickness in the reduced diameter portion 27c). Furthermore, in the central body portion 27b, the thickness t3 of the outer layer 25 is 0.25 to 4.0 times the thickness T3 of the inner layer 24. Since the thickness t2 of the outer layer 25 is 0.19 or more times the thickness T2 of the inner layer 24 and the thickness t3 of the outer layer 25 is 0.25 or more times the thickness T3 of the inner layer 24, the amount of mechanically recycled polyester used in the preform 23 can be increased. This reduces the environmental impact of the plastic bottle 10 produced from the preform 23. Furthermore, since the thickness t2 of the outer layer 25 is 4.0 or less times the thickness T2 of the inner layer 24 and the thickness t3 of the outer layer 25 is 4.0 or less times the thickness T3 of the inner layer 24, the ratio of the thicknesses t2 and t3 of the outer layer 25 to the thicknesses T2 and T3 of the inner layer 24 can be prevented from becoming too large. This prevents the mechanically recycled polyester contained in the outer layer 12 from being exposed from the inner surface of the inner layer 11 in the plastic bottle 10 produced from the preform 23. Furthermore, this prevents the ratio of the thicknesses t2 and t3 of the outer layer 25 to the thicknesses T2 and T3 of the inner layer 24 from becoming too large, allowing the plastic bottle 10 produced from the preform 23 to be made thinner.

[0094] The thickness t1 of outer layer 25 at neck portion 27a is preferably 0.1 mm or more and 2.5 mm or less. When the thickness t1 of outer layer 25 is 0.1 mm or more, the environmental impact of plastic bottle 10 made from preform 23 can be further reduced. Furthermore, when the thickness t1 of outer layer 25 is 2.5 mm or less, the thickness of plastic bottle 10 made from preform 23 can be made thinner.

[0095] The thickness t2 of outer layer 25 at reduced diameter portion 27c is preferably 0.23 mm or more and 3.2 mm or less. When the thickness t2 of outer layer 25 is 0.23 mm or more, the environmental impact of plastic bottle 10 made from preform 23 can be further reduced. Furthermore, when the thickness t2 of outer layer 25 is 3.2 mm or less, the thickness of plastic bottle 10 made from preform 23 can be made thinner.

[0096] The thickness t3 of the outer layer 25 in the central body portion 27b is preferably 0.3 mm or more and 3.2 mm or less. When the thickness t3 of the outer layer 25 is 0.3 mm or more, the environmental impact of the plastic bottle 10 produced from the preform 23 can be further reduced. Furthermore, when the thickness t3 of the outer layer 25 is 3.2 mm or less, the plastic bottle 10 produced from the preform 23 can be made thinner.

[0097] Furthermore, in the central trunk portion 27b, the thickness of the portion of the outer layer 25 where the thickness t3 is the thickest is 100% to 110%, preferably 100% to 105%, of the thickness of the portion of the outer layer 25 where the thickness t3 is the thinnest. This prevents the flow of injected resin from being obstructed in the region of the central trunk portion 27b where the outer layer 25 is to be formed when the outer layer 25 is produced by injection molding. This prevents the occurrence of so-called short shots.

[0098] As shown in Fig. 2, the mouth portion 26 is not provided with the inner layer 24, and only the outer layer 25 is provided. On the other hand, the inner layer 24 and the outer layer 25 are provided in the central portion 27b and the reduced diameter portion 27c of the body portion 27, and the bottom portion 28. Here, the mechanically recycled polyester contained in the outer layer 25 may have a different color from the virgin polyester, biomass-derived polyester, or chemically recycled polyester contained in the inner layer 24. In this case, the color of the preform 23 differs between the portion where the inner layer 24 is not provided and the portion where the inner layer 24 is provided.

[0099] For example, the mechanically recycled polyester contained in the outer layer 25 may have a lower brightness than the virgin polyester, biomass-derived polyester, or chemically recycled polyester contained in the inner layer 24. In this case, the brightness of the preform 23 may be lower in the mouth portion 26 where the inner layer 24 is not provided than in the middle body portion 27b where the inner layer 24 is provided. For example, * a * b * Lightness L in the color system * The value of L of the middle trunk portion 27b is 70.0 or more and 86.5 or less. * a * b * Lightness L in the color system * The value of may be greater than or equal to 86.6 and less than or equal to 94.0.

[0100] As used herein, L * a * b * Lightness L in the color system * The value is measured in accordance with JIS Z8722:2009.

[0101] Mouth 26L * a * b * Lightness L in the color system *Specifically, the value of can be measured by the following method. A sample is prepared by cutting the preform 23 into small pieces and cutting out only the mouth portion 26. Next, the sample is pre-cooled under liquid nitrogen for 10 minutes using a freeze-mill (6870 model Freezer / Mill, manufactured by SPEX Corporation), and then freeze-milled under liquid nitrogen for 10 minutes to obtain a powder. Next, this powder is measured using a spectrophotometer (CMS-35SP, manufactured by Murakami Color Research Laboratory Co., Ltd.) to measure the L * a * b * Lightness L in the color system * The measurement conditions are SCE (specular reflection excluded), 10° field of view, and D65 light source. * a * b * Lightness L in the color system * The value of L of the mouth portion 26 is calculated except that the sample is prepared by cutting out only the central body portion 27b from the preform 23. * a * b * Lightness L in the color system * It can be measured by a method similar to that for measuring the value of

[0102] The outer layer 25 of such a preform 23 is a layer produced by injection molding synthetic resin pellets. Specifically, the outer layer 25 is a layer obtained by injecting an injection resin onto the outer surface of the inner layer 24. By producing the outer layer 25 by injecting an injection resin onto the outer surface of the inner layer 24 in this way, the adhesion between the outer layer 25 and the inner layer 24 can be improved, and delamination between the inner layer 24 and the outer layer 25 can be suppressed.

[0103] Next, the operation of this embodiment having the above-described configuration, that is, the method for manufacturing the preform 23 and the method for manufacturing the plastic bottle 10, will be described with reference to FIGS. 3 to 8(a)-(d).

[0104] First, as shown in Fig. 3, a first mold assembly 70A is prepared, which includes a first cavity side mold 71 and a core side mold 73 including a core 72. Next, the core 72 is inserted into the first cavity side mold 71. In this manner, the first cavity side mold 71 and the core side mold 73 are clamped together. Here, the inner surface of the first cavity side mold 71 has a shape corresponding to the outer surface of the inner layer 24 of the preform 23, and the outer surface of the core 72 of the core side mold 73 has a shape corresponding to the inner surface of the inner layer 24 of the preform 23. Furthermore, a gate (injection port) 74 for injecting injection resin is formed in the first cavity side mold 71 at a position corresponding to the bottom 28 of the preform 23.

[0105] Next, as shown in Fig. 4, an injection resin is injected into the space between the first cavity side mold 71 and the core 72. At this time, with the first cavity side mold 71 and the core side mold 73 clamped together, an injection resin containing virgin polyester or the like is injected into the space between the first cavity side mold 71 and the core 72 from an injection resin gate 74 provided on the first cavity side mold 71. The injection resin injected from the gate 74 enters between the first cavity side mold 71 and the core 72. As a result, an inner layer 24 containing virgin polyester or the like is formed.

[0106] Then, as shown in FIG. 5, the first cavity side mold 71 of the first mold combination 70A is removed from the core side mold 73 and the inner layer 24 that has been produced.

[0107] Next, as shown in FIG. 6 , a second mold assembly 70B is prepared, which includes a second cavity side mold 75, a core side mold 73 including a core 72, and a separable lip mold 77. At this time, the fabricated inner layer 24 is attached to the core 72 of the core side mold 73. Next, the core 72 with the inner layer 24 attached is inserted into the second cavity side mold 75. At this time, the lip mold 77 is first attached to the core side mold 73. Next, the core 72 is brought close to the second cavity side mold 75, and the core 72 is inserted into the second cavity side mold 75. In this manner, the second cavity side mold 75, the core side mold 73, and the lip mold 77 are clamped together. In this manner, the second cavity side mold 75, the core side mold 73, and the lip mold 77 are clamped together. Here, the inner surface of the second cavity side mold 75 has a shape corresponding to the outer surface of the outer layer 25 of the preform 23. Furthermore, in the second cavity side mold 75, a gate (injection port) 76 for injecting the injection resin is formed at a position corresponding to the bottom 28 of the preform 23.

[0108] Next, as shown in FIG. 7 , an injection resin is injected into the space between the second cavity side mold 75 and the inner layer 24 attached to the core 72. That is, the injection resin is injected onto the outer surface of the inner layer 24. At this time, with the second cavity side mold 75, the core side mold 73, and the lip mold 77 clamped together, an injection resin containing mechanically recycled polyester is injected from an injection resin gate 76 provided on the second cavity side mold 75 into the space between the second cavity side mold 75, the lip mold 77, and the inner layer 24. The injection resin injected from the gate 74 enters between the second cavity side mold 75, the lip mold 77, and the inner layer 24. This forms an outer layer 25 containing mechanically recycled polyester. In this way, the inner layer 24 and the outer layer 25 are integrally formed, and a preform 23 is formed, which includes the inner layer 24 and the outer layer 25 arranged outside the inner layer 24.

[0109] The obtained preform 23 is then taken out from the second mold combination 70B.

[0110] Next, a method for manufacturing the plastic bottle 10 will be described.

[0111] First, the preform 23 is prepared (see FIG. 8(a)). At this time, the preform 23 is produced by, for example, the method shown in FIGS.

[0112] Next, the preform 23 is heated (see FIG. 8(b)). At this time, the preform 23 is heated uniformly in the circumferential direction by the heating device 51 while rotating with the mouth portion 26 facing downward. The heating temperature of the preform 23 in this heating step may be, for example, 90°C to 130°C.

[0113] Thereafter, the preform 23 is biaxially stretched and blow-molded (see FIG. 8(c)). At this time, the preform 23 is first mounted in a blow-molding mold 80 for blow-molding. This blow-molding mold 80 has a pair of mutually separated body molds 81 and 82 and a bottom mold 83. The body molds 81 and 82 have shapes corresponding to the neck 14, shoulder 15, and body 16 of the plastic bottle 10. The bottom mold 83 has a shape corresponding to the bottom 17 of the plastic bottle 10.

[0114] Next, blowing air is blown into the preform 23, causing the preform 23 to expand within the cavity of the blow molding die 80 until it becomes the molded product, plastic bottle 10 (see FIG. 8(c)). After the plastic bottle 10 has been molded in the blow molding die 80 in this manner, the die is opened and the finished plastic bottle 10 is removed from the blow molding die 80 (see FIG. 8(d)).

[0115] In this way, the plastic bottle 10 shown in FIG. 1 is obtained.

[0116] As described above, according to this embodiment, inner layer 24 of preform 23 contains virgin polyester, biomass-derived polyester, or chemically recycled polyester, and outer layer 25 contains mechanically recycled polyester. Furthermore, inner layer 24 is disposed in mid-body portion 27b and reduced diameter portion 27c of body portion 27. As a result, in plastic bottle 10 produced from preform 23, the inner surfaces of outer layer 12 of shoulder portion 15 and body portion 16 are covered with inner layer 11. This allows inner layer 11 to be disposed in an area of ​​the inner surface of plastic bottle 10 that is likely to come into contact with the contents for an extended period of time when plastic bottle 10 is held upright.

[0117] In this case, the inner layer 24 is not provided above the lower end of the support ring 26a of the mouth 26. As a result, in the plastic bottle 10 produced from the preform 23, the inner layer 11 is not provided above the lower end of the support ring 13c of the mouth 13. This prevents the inner layer 11 from being provided in areas that are unlikely to come into contact with the contents for long periods of time. As a result, the ratio of the amount of mechanically recycled polyester used, which is the material for the outer layer 12, to the amount of virgin polyester or the like used, which is the material for the inner layer 11, can be increased. This reduces the environmental impact of the plastic bottle 10 produced from the preform 23.

[0118] Furthermore, according to this embodiment, in at least a portion of the reduced diameter portion 27c, the thickness y (radial distance) of the inner layer 24 gradually decreases from the middle barrel portion 27b toward the neck portion 27a. This prevents the flow of injected resin from being obstructed in the region of the reduced diameter portion 27c where the inner layer 24 is to be formed when the inner layer 24 is produced by injection molding. This prevents the injection resin from reaching the entire region where the inner layer 24 is to be formed, a so-called short shot.

[0119] Furthermore, in the above-described embodiment, an example has been described in which the inner layer 24 includes the gate mark 24b and the outer layer 25 includes the gate mark 25a, but this is not limiting. For example, although not shown, the inner layer 24 may not include the gate mark 24b. In this case, for example, by adjusting the length of the gate 74 of the first-cavity mold 71, it is possible to prevent the gate mark 24b from being formed in the inner layer 24. Similarly, the outer layer 25 may not include the gate mark 25a. In this case, for example, by adjusting the length of the gate 76 of the second-cavity mold 75, it is possible to prevent the gate mark 25a from being formed in the outer layer 25.

[0120] In the above-described embodiment, the plastic bottle 10 has been described in which the inner layer 11 is not provided above the lower end of the support ring 13c of the mouth portion 13. Also, the preform 23 has been described in which the inner layer 24 is not provided above the lower end of the support ring 26a of the mouth portion 26. However, the positions of the inner layer 11 and the inner layer 24 are not limited to this.

[0121] As shown in Fig. 9, the inner layer 11 of the plastic bottle 10 may extend above and below the lower end of the support ring 13c of the mouth 13. In the example shown in Fig. 9, the mouth 13, neck 14, shoulder 15, body 16, and bottom 17 of the plastic bottle 10 include the inner layer 11. The inner layer 11 is provided below the upper end of the mouth 13. The inner layer 11 is not provided at the upper end of the mouth 13. The inner layer 11 is provided continuously from a position above the lower end of the mouth 13 to the bottom 17.

[0122] As shown in Figure 9, by not providing the inner layer 11 at the upper end of the mouth portion 13, the ratio of the amount of material used for the outer layer 12 to the amount of material used for the inner layer 11 can be made larger than when the inner layer 11 is provided at the upper end of the mouth portion 13.

[0123] The plastic bottle 10 shown in Fig. 9 is produced from a preform 23 shown in Fig. 10. In the example shown in Fig. 10, the inner layer 24 of the preform 23 is provided above and below the lower end of the support ring 26a of the mouth portion 26. In the example shown in Fig. 10, the mouth portion 26, body portion 27, and bottom portion 28 of the preform 23 include the inner layer 24. The inner layer 24 is provided below the upper end of the mouth portion 26. The inner layer 24 is provided continuously from a position above the lower end of the mouth portion 26 to the bottom portion 28.

[0124] 10, the thickness y of the inner layer 24 gradually decreases from the lower end of the reduced diameter portion 27c toward the upper end of the inner layer 24. This prevents the flow of injected resin from being obstructed in the region where the inner layer 24 is to be formed when the inner layer 24 is produced by injection molding. This prevents the injection resin from reaching the entire region where the inner layer 24 is to be formed, which is known as a short shot.

[0125] The components disclosed in the above-described embodiment and each modification may be combined as needed, or some components may be omitted from all the components shown in the above-described embodiment and each modification. [Explanation of symbols]

[0126] 10 plastic bottles 23 Preform 24 Inner layer 25 Outer layer 26 Mouth 26a Support Ring 27 Torso 27a Neck 27b Middle torso 27c Reduced diameter part 28 Bottom

Claims

1. a mouth portion having a support ring; a body portion connected to the mouth portion; a bottom portion connected to the body portion, the body portion has a neck portion located on the support ring side, a middle body portion located on the bottom side, and a tapered portion located between the neck portion and the middle body portion, the diameter of which is tapered from the neck portion side toward the middle body portion side, the neck portion, the middle portion, and the reduced diameter portion of the body portion include an outer layer having mechanically recycled polyester; the central trunk portion and the reduced diameter portion are located inside the outer layer and include an inner layer containing virgin polyester, biomass-derived polyester, or chemically recycled polyester; a thickness of the inner layer gradually decreasing from the middle body portion side toward the neck portion side in at least a part of the reduced diameter portion;

2. The preform according to claim 1 , wherein an upper end of the inner layer is spaced from the support ring by 0 mm or more and 9 mm or less.

3. When the distance from the upper end of the inner layer is X and the thickness of the inner layer of the reduced diameter portion at a position where the distance from the upper end of the inner layer is X is Y, 0.0166 x X ≤ Y ≤ 2.5875 x X 3. The preform according to claim 1, wherein the following relationship holds:

4. 4. The preform according to claim 1, wherein in the middle trunk portion, the thickness of the thickest portion of the outer layer is 100% or more and 110% or less of the thickness of the thinnest portion of the outer layer.

5. 5. The preform according to claim 1, wherein in the middle trunk portion, the thickness of the thickest portion of the inner layer is 100% or more and 110% or less of the thickness of the thinnest portion of the inner layer.

6. The preform according to claim 1 , wherein the thickness of the outer layer in the middle trunk portion is 0.25 to 4.0 times the thickness of the inner layer.

7. The L of the mouth ＊ a ＊ b ＊ Lightness L in the color system ＊ The value of L of the middle trunk portion is 70.0 or more and 86.5 or less. ＊ a ＊ b ＊ Lightness L in the color system ＊ The preform according to any one of claims 1 to 6, wherein the value of is equal to or greater than 86.6 and equal to or less than 94.

0.

8. A preform described in any one of claims 1 to 7, wherein the upper end of the inner layer is located closer to the bottom than the support ring.

9. A preform described in any one of claims 1 to 8, wherein the portion in which the thickness of the inner layer gradually decreases from the middle body side toward the neck side continues to the upper end of the inner layer.

10. a mouth portion having a support ring; a neck portion connected to the mouth portion; a shoulder portion connected to the neck portion; a torso portion connected to the shoulder portion; a bottom portion connected to the body portion, the shoulder and torso regions include outer layers having mechanically recycled polyester; the trunk portion includes an inner layer located inside the outer layer and having virgin polyester, biomass-derived polyester, or chemically recycled polyester; A plastic bottle, wherein the thickness of the inner layer in at least a portion of the shoulder portion gradually decreases from the body portion side toward the mouth portion side.

11. A plastic bottle as described in Claim 10, wherein the upper end of the inner layer is located closer to the bottom than the support ring.

12. A plastic bottle as described in claim 10 or 11, wherein the portion in which the thickness of the inner layer gradually decreases from the body side toward the mouth side continues to the upper end of the inner layer.

13. A method for manufacturing a plastic bottle, comprising: Providing a preform according to any one of claims 1 to 9; heating the preform; and biaxially stretching and blow-molding the preform.

Images