Method for manufacturing preforms and methods for manufacturing containers

Abstract

The present invention provides a method for manufacturing preforms that enables the production of containers with excellent gas barrier properties and a good appearance. [Solution] The method for manufacturing the preform 30 of the present disclosure comprises, in this order, a step of applying a surface treatment to the outside of the support 21, and a step of forming a barrier layer 22 on the outside of the support 21, wherein the preform 30 comprises a support 21 and a barrier layer 22 provided on the outside of the support 21, and the barrier layer 22 contains a carboxyl group-containing resin and a polyvinyl alcohol-based resin.

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a preform and a method for manufacturing a container manufactured by blow molding the preform.

Background Art

[0002] Containers (such as PET bottles) formed by stretch blow molding a thermoplastic polyester resin such as polyethylene terephthalate resin have excellent transparency and surface gloss, and also have the impact resistance, rigidity, and gas barrier properties required for containers. They are widely used as containers for various liquids such as beverages, seasonings, and cosmetics.

[0003] When the container has a multi-layer structure and a beverage containing carbon dioxide gas (such as carbonated water) is contained in the container as the content, the carbon dioxide gas passes through the base material layer and stays in a blister (water bulge) shape between the outer layer, which may cause the outer layer to float and become a factor for poor appearance.

[0004] As a container that can solve such problems, for example, Patent Document 1 describes a synthetic resin container characterized in that the resin layer on the radially outer side adjacent in the thickness direction has a higher carbon dioxide gas permeability coefficient than the resin layer on the radially inner side. According to this synthetic resin container, the retention of carbon dioxide gas between the base material layer and the outer layer can be suppressed.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the synthetic resin container described in Patent Document 1, the carbon dioxide permeability coefficient of the radially outer resin layer was large, and the container as a whole did not have sufficient gas barrier properties.

[0007] Therefore, the object of this disclosure is to provide a method for manufacturing a preform that can produce a container with excellent gas barrier properties and a good appearance. Another object of this disclosure is to provide a method for manufacturing a container using the method for manufacturing the preform. [Means for solving the problem]

[0008] The inventors have found that when manufacturing a preform comprising a support and a barrier layer, by performing a predetermined surface treatment on the outside of the support in advance and providing a barrier layer with excellent gas barrier properties on the surface-treated support, the adhesion between the support and the barrier layer is improved, and carbon dioxide gas is less likely to accumulate between the layers even after the preform is blow-molded to manufacture a container. This disclosure was completed after further consideration based on the aforementioned findings.

[0009] This disclosure is resolved by the following embodiments. <1> A method for manufacturing a preform, comprising the steps of: applying a surface treatment to the outside of a support; and forming a barrier layer on the outside of the support, in this order, The preform comprises the support and the barrier layer provided on the outside of the support. A method for producing a preform, wherein the barrier layer comprises a carboxyl group-containing resin and a polyvinyl alcohol-based resin. <2> The aforementioned surface treatment is corona treatment, UV ozone treatment, plasma treatment, or flame treatment. <1> A method for manufacturing the preform described above. <3> The aforementioned surface treatment is an excimer treatment. <1> A method for manufacturing the preform described above. <4> The mass ratio of the carboxyl group-containing resin to the polyvinyl alcohol-based resin is 1 / 20 or more and 10 / 1 or less. <1> ~ <3> A method for manufacturing a preform as described in any one of the following. <5> The carboxyl group-containing resin is polyacrylic acid. <1> ~ <4> A method for manufacturing a preform as described in any one of the following. <6> The support comprises polyester, <1> ~ <5> A method for manufacturing a preform as described in any one of the following. <7> The preform comprises a protective layer on the outside of the barrier layer. <1> ~ <6> A method for manufacturing a preform as described in any one of the following. <8> The protective layer comprises a copolymerized polyester, <7> A method for manufacturing the preform described above. <9> The copolymerized polyester contains ethylene glycol and neopentyl glycol or propylene glycol as diol components. <8> A method for manufacturing the preform described above. <10> The copolymerized polyester contains terephthalic acid as a dicarboxylic acid component. <8> or <9> A method for manufacturing the preform described above. <11> <1> ~ <10> A method for manufacturing a container, comprising the steps of manufacturing a preform by any one of the methods for manufacturing a preform described in the following order: and manufacturing a container by blow molding the preform. [Effects of the Invention]

[0010] This disclosure provides a method for manufacturing a preform that can produce a container with excellent gas barrier properties and a good appearance. Furthermore, this disclosure can provide a method for manufacturing a container using the method for manufacturing the preform. [Brief explanation of the drawing]

[0011] [Figure 1]It is a schematic semi-cross-sectional view showing an embodiment of the preform of the present disclosure. [Figure 2] It is a schematic semi-cross-sectional view showing an embodiment of the preform of the present disclosure. [Figure 3] It is a schematic semi-cross-sectional view showing an embodiment of the preform of the present disclosure. [Figure 4] It is a schematic semi-cross-sectional view showing an embodiment of the preform of the present disclosure. [Figure 5] It is a schematic semi-cross-sectional view showing an embodiment of the container of the present disclosure. [Figure 6] It is a schematic semi-cross-sectional view showing an embodiment of the container of the present disclosure. [Figure 7] It is a schematic semi-cross-sectional view showing an embodiment of the container of the present disclosure. [Figure 8] It is a schematic semi-cross-sectional view showing an embodiment of the container of the present disclosure.

Mode for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, for the sake of illustration and ease of understanding, the scale, the aspect ratio of the vertical and horizontal dimensions, etc. are appropriately changed and exaggerated from those of the actual object.

[0013] <Preform> First, an embodiment of the preform manufactured by the manufacturing method of the preform of the present disclosure will be described. The preform includes a support and a barrier layer. Since the preform of the present disclosure has excellent gas barrier properties even after blow molding, it can be suitably used as a preform for a blow-molded container.

[0014] Figure 1 is a schematic half-cross-sectional view showing one embodiment of the preform. As shown in Figure 1, the preform 30 comprises a mouth portion 31, a body portion 32 connected to the mouth portion 31, and a bottom portion 33 connected to the body portion 32. The mouth portion 31 corresponds to the mouth portion 11 of the container 10 described later, and has substantially the same shape as the mouth portion 11. The body portion 32 corresponds to the neck portion 12, shoulder portion 13, and body portion 14 of the container 10, and has a substantially cylindrical shape. The bottom portion 33 corresponds to the bottom portion 15 of the container 10, and has a substantially hemispherical shape.

[0015] The opening 11 includes a threaded portion 34 corresponding to the threaded portion 16 of the container 10 (described later) to which a cap (not shown) is screwed; a caliper 35 provided below the threaded portion 34 and corresponding to the caliper 17 of the container 10; and a support ring 36 provided below the caliper 35 and corresponding to the support ring 18 of the container 10. The shape of the opening 11 may be a conventionally known shape. In this specification, "upper" and "lower" refer to the upper and lower parts of the container 10, as described later, when it is in an upright position (Figures 5-8).

[0016] As shown in Figure 1, the preform 30 comprises a support 37 and a barrier layer 38. Also as shown in Figure 1, the mouth portion 31 is made up of the support 37, and the body portion 32 and bottom portion 33 are made up of the support 37 and the barrier layer 38. Furthermore, as shown in Figure 1, the barrier layer 38 is provided on the outside of the preform 30 so as to surround the preform 30. The barrier layer 38 may be provided over the entire or partial area of ​​the body 32 and / or bottom 33.

[0017] In one embodiment, as shown in Figure 2, the preform has a barrier layer 38 covering at least 0.4L to 0.6L of the entire outer surface, with the lower end of the mouth 11 being "0L" and the lower end of the bottom 33 being "1L". This efficiently improves the gas barrier properties of the container obtained from the preform. Preferably, the preform has a barrier layer covering at least 0.2L to 0.7L of the entire outer surface, and more preferably, the barrier layer covers at least 0.1L to 0.9L of the entire outer surface.

[0018] As shown in Figures 3 and 4, the preform 30 may have a protective layer 39 provided on the outside of the barrier layer 38.

[0019] The preform 30 shown in Figure 3 has a mouth portion 31 made up of a support 37, and the body portion 32 and bottom portion 33 are made up of the support 37, a barrier layer 38, and a protective layer 39. The barrier layer 38 is provided on the entire outside of the support 37 so as to surround the support 37. The protective layer 39 is provided on the entire outside of the barrier layer 38 so as to surround the barrier layer 38. The protective layer 39 may be provided over the entire or partial area of ​​the body 32 and / or bottom 33.

[0020] In the preform 30 shown in Figure 4, a barrier layer 38 and a protective layer 39 are provided over the entire outer surface area of ​​at least 0.4L to 0.6L, with the lower end of the mouth 31 being "0L" and the lower end of the bottom 33 being "1L". By configuring the preform in this way, a container with efficiently improved gas barrier properties can be obtained. Preferably, the preform 30 has a barrier layer 38 and a protective layer 39 over the entire outer surface area of ​​at least 0.2 L to 0.7 L, and more preferably, the barrier layer 38 and protective layer 39 over the entire outer surface area of ​​at least 0.1 L to 0.9 L.

[0021] The cross-sectional thickness of the preform is preferably 1.4 mm or more and 4.5 mm or less, and more preferably 2.5 mm or more and 3.5 mm or less. The thickness of the cross-section of the preform can be measured, for example, in the body of the preform which has at least a support and a barrier layer, and refers to the thickness of the cross-section at the point where the cross-sectional thickness is smallest.

[0022] The support, barrier layer, and protective layer of the preform are described below.

[0023] (Support) The support is capable of maintaining the shape of the container. In one embodiment, the support includes a thermoplastic resin. Examples of thermoplastic resins included in the support include polyolefins such as polyethylene and polypropylene, polycarbonate, polyvinyl chloride, polyesters such as polyethylene terephthalate, polyamides such as nylon 6 and nylon 6,6, and mixtures thereof. Among these, the support preferably includes polyester from the viewpoint of gas barrier properties and strength. The support preferably includes polyethylene terephthalate from the viewpoint of recyclability.

[0024] In this specification, "polyester" means a polymer polymerized by ester bonds. Such polyesters are usually obtained by polycondensation 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, dodecanedionic acid, eicosanedionic acid, pimelic acid, azelaic acid, methylmalonic acid and 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-sodium sulfisoisophthalic acid, phenylendanedicarboxylic acid, anthracenedicarboxylic acid, phenantradicarboxylic acid, 9,9'-bis(4-carboxyphenyl)fluorenic acid and their ester derivatives. 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, norbornanediethanol, norbornanediethanol, tricyclodecanedimethanol, tricyclodecaneethanol, tetracyclododecanedimethanol, tetracyclododecaneethanol, decalindiethanol, decalindiethanol, 5-methylol-5-ethyl Examples include -2-(1,1-dimethyl-2-hydroxyethyl)-1,3-dioxane, cyclohexanediol, bicyclohexyl-4,4'-diol, 2,2-bis(4-hydroxycyclohexyl)propane, 2,2-bis(4-(2-hydroxyethoxy)cyclohexyl)propane, cyclopentanediol, 3-methyl-1,2-cyclopentadiol, 4-cyclopentene-1,3-diol, adamandiol, paraxylene glycol, bisphenol A, bisphenol S, styrene glycol, trimethylolpropane, pentaerythritol, and bis-β-hydroxyethyl terephthalate (BHET).

[0025] The polyester is preferably polyethylene terephthalate, or modified polyethylene terephthalate obtained by polymerizing polyethylene terephthalate raw material monomers with copolymer monomers. The copolymer monomer can be appropriately selected from the dicarboxylic acid and diol components mentioned above.

[0026] Within the limits that do not impair the properties of the present disclosure, the polyester may contain monomers other than the dicarboxylic acid and diol components, but the content thereof is preferably 10 mol% or less, more preferably 5 mol% or less, and even more preferably 3 mol% or less, relative to the total constituent units.

[0027] Polyester may be polymerized using a polymerization catalyst. Examples of polymerization catalysts include manganese (Mn) catalysts, titanium (Ti) catalysts, aluminum (Al) catalysts, lithium (Li) catalysts, germanium (Ge) catalysts, and antimony (Sb) catalysts.

[0028] The polyester mentioned above may be virgin polyester, or recycled polyester from the perspective of reducing environmental impact. In this specification, "virgin polyester" means polyester that has not been recycled as described above, and "recycled polyester" means polyester that has been collected and recycled from used containers and other products that have been shipped to the market. Furthermore, recycled polyesters include polyester obtained by decomposing collected used polyester containers to the monomer level and repolymerizing them (hereinafter referred to as "chemically recycled polyester"), and polyester obtained by sorting, crushing, and washing collected used products to remove contaminants and foreign matter to obtain flakes, and then further treating the flakes at high temperature and reduced pressure for a certain period of time to remove contaminants from inside the resin (hereinafter referred to as "mechanically recycled polyester"). Mechanically recycled polyester may contain two or more catalysts. In this case, mechanically recycled polyester may contain, for example, two or more of the following: Sb catalyst polyester, Mn catalyst polyester, Ti catalyst polyester, Al catalyst polyester, Li catalyst polyester, and Ge catalyst polyester.

[0029] It is known that mechanically recycled polyester has different content ratios of antimony (Sb), sodium (Na), calcium (Ca), and / or magnesium (Mg) compared to virgin polyester and chemically recycled polyester. Specifically, mechanically recycled polyester is known to contain Sb at a ratio of 20 mg / L to 54 mg / L, Na at a ratio of 12 mg / L or more, Ca at a ratio of 4 mg / L or more, and / or Mg at a ratio of 2.5 mg / L or more. Therefore, mechanically recycled polyester can be distinguished from virgin polyester and chemically recycled polyester by whether or not it satisfies one or more of these element content ratios. Furthermore, in mechanically recycled polyester, the content of Sb is preferably 25 mg / L or more and 50 mg / L or less, the content of Na is preferably 14 mg / L or more, the content of Ca is preferably 4.5 mg / L or more, and the content of Mg is preferably 3 mg / L or more.

[0030] If the support contains mechanically recycled polyester, the content of 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, based on 100 parts by mass of the total amount of resin constituting the support.

[0031] From the viewpoint of recyclability, the content of one type of thermoplastic resin in the support is preferably 90% by mass or more, and more preferably 97% by mass or more.

[0032] The support may contain a resin in addition to polyester, to the extent that it does not impair the properties of the present disclosure. Examples of resins include polyethylene, polypropylene, polystyrene, polyvinyl chloride, acrylic resin, polyamide, polyacetal, and polycarbonate. These resins can be used individually or in combination of two or more. From the viewpoint of recyclability, the content of these resins is preferably less than 10% by mass, and more preferably less than 3% by mass.

[0033] The support may contain additives to the extent that they do not impair the properties of the present disclosure. Examples of additives include oxygen absorbers, plasticizers, UV stabilizers, antioxidants, matting agents, deodorants, flame retardants, weathering agents, antistatic agents, friction reducers, slip agents, mold release agents, antioxidants, and ion exchange agents. These additives can be used individually or in combination of two or more.

[0034] The support may be a single-layer structure or a multilayer structure of two or more layers. Furthermore, if the support is a multilayer structure, each layer may have the same composition, or it may have different compositions as long as it does not impair the properties of this disclosure.

[0035] The cross-sectional thickness of the support of the preform is preferably 1.3 mm or more and 4.3 mm or less, and more preferably 2.5 mm or more and 3.5 mm or less. The thickness of the cross-section of the preform support can be measured in the body of the preform, and refers to the thickness of the cross-section at the point where the cross-sectional thickness is smallest.

[0036] The preform support is subjected to an external surface treatment. Surface treatments include corona treatment, UV ozone treatment, plasma treatment, or flame treatment. This surface treatment improves the wettability of the outer surface of the support, thereby improving the adhesion between the support and the barrier layer. Details of the surface treatment will be described later.

[0037] (Barrier layer) The barrier layer is a layer that possesses gas barrier properties. Furthermore, the barrier layer is preferably a layer having light-shielding properties, gloss, color, etc., depending on the intended use of the container being manufactured.

[0038] The barrier layer comprises a carboxyl group-containing resin and a polyvinyl alcohol-based resin. Because the hydroxyl groups contained in polyvinyl alcohol resins form hydrogen bonds between molecules, polyvinyl alcohol resins are highly crystalline and cohesive. Furthermore, because polyvinyl alcohol resins are polar, intermolecular interactions occur, suppressing the dispersion of oxygen and carbon dioxide. For these reasons, polyvinyl alcohol resins have a high gas barrier effect, effectively blocking oxygen, water vapor, and carbon dioxide. Including polyvinyl alcohol resin in the barrier layer can improve the gas barrier properties of a container. Furthermore, the carboxyl groups in the carboxyl group-containing resin form hydrogen bonds with the "-OH" groups of the polyvinyl alcohol-based resin and the solvent in the coating solution used to form the barrier layer (e.g., water and organic solvents containing hydroxyl groups), increasing the viscosity of the coating solution. This allows for a thicker barrier layer with fewer coating applications, thereby improving the productivity of container production.

[0039] The following describes polyvinyl alcohol-based resins and carboxyl group-containing resins.

[0040] Polyvinyl alcohol-based resins (hereinafter also referred to as "PVA-based resins") are resins that contain alcoholic hydroxyl groups in the polymer structure. PVA-based resins are usually obtained by saponifying vinyl ester polymers.

[0041] Vinyl ester polymers are typically obtained by polymerizing vinyl ester monomers as polymerization components. Examples of vinyl ester monomers include fatty acid vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caprylate, vinyl versatate, and vinyl monochloroacetate, as well as aromatic carboxylic acid vinyl esters such as vinyl arene carboxylates (e.g., C7-12 arene carboxylic acid vinyl esters) such as vinyl benzoate. These monomers can be used individually or in combination of two or more.

[0042] Vinyl ester polymers may have units derived from other polymerizable monomers (monomers copolymerizable with vinyl esters). Examples of other polymerizable monomers include ethylene; α-olefins such as propylene, 1-butene, 1-pentene, 1-hexene, and 1-octene; alkyl methacrylates such as methyl methacrylate and ethyl methacrylate; chlorine-containing vinyl monomers such as vinyl chloride and vinylidene chloride; fluorine-containing vinyl monomers such as vinyl fluoride and vinylidene fluoride; unsaturated nitriles such as acrylonitrile and methacrylonitrile; aromatic vinyl monomers such as styrene and α-methylstyrene; and alkyl itaconate esters. These monomers can be used individually or in combination of two or more.

[0043] PVA-based resins may be modified in which some of the vinyl alcohol units are altered by reactions such as acetalization, etherification, acetoacetylation, or cationization.

[0044] The degree of polymerization of the PVA resin is preferably 1000 to 4000, more preferably 1500 to 3500, and even more preferably 2000 to 3000. The average degree of polymerization of PVA resin can be measured in accordance with JIS K 6726:1994.

[0045] The degree of saponification of the PVA resin is preferably 70 mol% to 99.9 mol%, more preferably 90 mol% to 99.5 mol%, and even more preferably 95 mol% to 99.5 mol%, from the viewpoint of excellent solubility in solvents and storage stability of the composition. The degree of saponification of PVA resins can be measured in accordance with JIS K 6726:1994.

[0046] When the PVA resin is dissolved in pure water at a concentration of 4% by mass, the viscosity of the aqueous solution is preferably 3 mPa·s to 70 mPa·s, more preferably 50 mPa·s to 68 mPa·s, and 54 mPa·s to 66 mPa·s. The viscosity of the aqueous solution can be measured at a temperature of 20°C in accordance with JIS Z 8803:2011.

[0047] PVA-based resins can be used individually or in combination of two or more types.

[0048] Existing carboxyl group-containing resins can be used. Existing carboxyl group-containing resins are a general term for resins that contain carboxyl groups in the polymer structure. Examples of carboxyl group-containing resins include homopolymers of carboxyl group-containing unsaturated monomers, copolymers of carboxyl group-containing unsaturated monomers, copolymers of carboxyl group-containing unsaturated monomers and other polymerizable monomers, and polysaccharides containing carboxyl groups in their molecules (hereinafter also referred to as "acidic polysaccharides"). These carboxyl group-containing resins can be used individually or in combination of two or more. Note that the carboxyl group includes not only free carboxyl groups but also acid anhydride groups (specifically, dicarboxylic acid anhydride groups). The acid anhydride groups may be partially ring-opened to form carboxyl groups. In carboxyl group-containing resins, some of the carboxyl groups may be neutralized with alkali.

[0049] The carboxyl group-containing unsaturated monomer is preferably an α,β-monoethylenically unsaturated carboxylic acid. Therefore, the carboxyl group-containing resin includes homopolymers of α,β-monoethylenically unsaturated carboxylic acids, copolymers of two or more α,β-monoethylenically unsaturated carboxylic acids, and copolymers of α,β-monoethylenically unsaturated carboxylic acids with other polymerizable monomers. Other polymerizable monomers include ethylenically unsaturated monomers.

[0050] Examples of α,β-monoethylenically unsaturated carboxylic acids include unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid; unsaturated dicarboxylic acids such as maleic acid, fumaric acid, and itaconic acid; and unsaturated dicarboxylic acid anhydrides such as maleic anhydride and itaconic anhydride. These acids can be used individually or in combination of two or more. The α,β-monoethylenically unsaturated carboxylic acid is preferably selected from one or more of acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, and itaconic acid, and more preferably selected from one or more of acrylic acid, methacrylic acid, and maleic acid.

[0051] Other polymerizable monomers copolymerizable with α,β-monoethylenically unsaturated carboxylic acids, particularly ethylenically unsaturated monomers, include, for example, ethylene; α-olefins such as propylene, 1-butene, 1-pentene, 1-hexene, and 1-octene; saturated vinyl carboxylates such as vinyl acetate; alkyl acrylates such as methyl acrylate and ethyl acrylate; alkyl methacrylates such as methyl methacrylate and ethyl methacrylate; chlorine-containing vinyl monomers such as vinyl chloride and vinylidene chloride; fluorine-containing vinyl monomers such as vinyl fluoride and vinylidene fluoride; unsaturated nitriles such as acrylonitrile and methacrylonitrile; aromatic vinyl monomers such as styrene and α-methylstyrene; and alkyl itaconate esters. These monomers can be used individually or in combination of two or more.

[0052] Examples of carboxyl group-containing polysaccharides include alginic acid, carboxymethylcellulose, pectin, and other acidic polysaccharides having a carboxyl group in their molecule. These acidic polysaccharides can be used individually or in combination of two or more. Acidic polysaccharides can also be used in combination with (co)polymers of α,β-monoethylene unsaturated carboxylic acids.

[0053] When the carboxyl group-containing resin is a copolymer of an α,β-monoethylenically unsaturated carboxylic acid and other ethylenically unsaturated monomers, the composition of the copolymer shall preferably consist of α,β-monoethylenically unsaturated carboxylic acid monomers of 60 mol% or more, more preferably 80 mol% or more, and even more preferably 90 mol% or more.

[0054] The carboxyl group-containing resin is preferably a homopolymer or copolymer obtained by polymerization of α,β-monoethylenically unsaturated carboxylic acids only. When the polycarboxylic acid polymer is a (co)polymer consisting only of α,β-monoethylenically unsaturated carboxylic acids, the carboxyl group-containing resin is preferably a homopolymer, copolymer, or mixture of two or more thereof obtained by carboxylic acids selected from one or more of acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, and itaconic acid, and more preferably a homopolymer, copolymer, or mixture of two or more thereof obtained by carboxylic acids selected from one or more of acrylic acid, methacrylic acid, and maleic acid.

[0055] The carboxyl group-containing resin is preferably selected from one or more of polyacrylic acid, polymethacrylic acid, and maleic acid polymers. Polyacrylic acid is preferred as the carboxyl group-containing resin because it is relatively easy to obtain and has good recyclability and gas barrier properties.

[0056] The number-average molecular weight of the carboxyl group-containing resin is preferably in the range of 2,000 to 10,000,000, more preferably in the range of 5,000 to 1,000,000, and even more preferably in the range of 10,000 to 500,000.

[0057] The mass ratio of the carboxyl group-containing resin to the polyvinyl alcohol-based resin (carboxyl group-containing resin / polyvinyl alcohol-based resin) is preferably 1 / 20 or more and 10 / 1 or less, more preferably 1 / 15 or more and 5 / 1 or less, and even more preferably 1 / 10 or more and 2 / 1 or less. By setting the above mass ratio to 1 / 20 or more, the recyclability of the container can be further improved. By setting the above mass ratio to 1 / 10 or less, the gas barrier properties of the container can be further improved. Note that the above mass ratios represent the solid content ratios.

[0058] The content of the carboxyl group-containing resin in the barrier layer is preferably 1% by mass or more and 80% by mass or less, more preferably 2% by mass or more and 70% by mass or less, and even more preferably 5% by mass or more and 60% by mass or less, relative to the total components contained in the barrier layer. By increasing the content of carboxyl group-containing resin to 1% by mass or more, the recyclability of the container can be further improved. By limiting the content of carboxyl group-containing resin to 80% by mass or less, the gas barrier properties of the container can be further improved.

[0059] The content of polyvinyl alcohol-based resin in the barrier layer is preferably 20% to 99% by mass, more preferably 30% to 98% by mass, and even more preferably 40% to 95% by mass, relative to the total components contained in the barrier layer. By increasing the polyvinyl alcohol-based resin content to 20% by mass or more, the gas barrier properties of the container can be further improved. By limiting the polyvinyl alcohol-based resin content to 99% by mass or less, the recyclability of the container can be further improved.

[0060] The barrier layer may contain additives to the extent that they do not impair the properties of the present disclosure. Examples of additives include oxygen absorbers, plasticizers, UV stabilizers, antioxidants, matting agents, deodorants, flame retardants, weathering agents, antistatic agents, thread friction reducers, slip agents, mold release agents, antioxidants, and ion exchange agents. These additives can be used individually or in combination of two or more.

[0061] The barrier layer may be a single layer or a multilayer structure of two or more layers. Furthermore, if the barrier layer is multilayer, each layer may have the same composition or different compositions.

[0062] The thickness of the barrier layer is preferably 2.0 μm to 1000.0 μm, and more preferably 20.0 μm to 500.0 μm. This improves blow moldability and gas barrier properties after blow molding. The thickness of the barrier layer can be measured, for example, on the body of the preform, and refers to the thickness of the cross-section at the point where the cross-sectional thickness of the barrier layer is smallest. Furthermore, if the barrier layer is multilayered, the thickness of the barrier layer is the sum of the thicknesses of all layers.

[0063] The barrier layer may be colored red, blue, yellow, green, brown, reddish-brown, orange, black, and white, and may be transparent or opaque. The coloring of the barrier layer allows it to absorb light entering the container from the outside, such as sunlight, thereby suppressing changes in the taste and color of the contents. Since it can effectively absorb visible light with wavelengths between 400 nm and 500 nm, the barrier layer is preferably colored reddish-brown or orange. For example, a coloring agent can be used to color the barrier layer.

[0064] (protective layer) The protective layer is intended to protect the barrier layer. In one embodiment, the protective layer comprises a copolymerized polyester. The presence of a protective layer in the container helps to suppress the deterioration of the barrier layer during manufacturing and use, from physical factors such as damage or peeling of the barrier layer, and from chemical factors such as moisture absorption or dissolution.

[0065] The copolymerized polyester is obtained by polycondensation of terephthalic acid as the main dicarboxylic acid component and ethylene glycol as the main diol component, and contains neopentyl glycol or propylene glycol as diol components in addition to ethylene glycol as copolymerized components. In this specification, "main" means that each component is present in an amount of more than 50 mol%, with the total constituent units of each component being 100 mol%. More preferably it is 55 mol% or more, and even more preferably 60 mol% or more.

[0066] The copolymerized polyester has a weight-average molecular weight between 1,000 and 20,000. In this disclosure, a copolymerized polyester containing neopentyl glycol or propylene glycol as a diol copolymer component and having a weight-average molecular weight within the above range is used as a constituent material for the protective layer. If the weight-average molecular weight (hereinafter sometimes referred to as Mw) of the copolymerized polyester is 1,000 or less, tack will occur in the protective layer, worsening the handling of the container. The preferred range for the Mw of the copolymerized polyester is 10,000 to 18,000. Note that the weight-average molecular weight refers to the value calculated by gel permuration chromatography according to the standard method.

[0067] In one embodiment, the copolymerized polyester may contain components other than neopentyl glycol or propylene glycol as diol copolymerization components, to the extent that they do not impede the effects of the present disclosure. For example, it may contain aliphatic diols such as diethylene glycol, triethylene glycol, 1,4-butanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,5-pentanediol, 2,2-diethyl-1,3-propanediol, 1,9-nonanediol, and 1,10-decanediol, alicyclic diols such as 1,4-cyclohexanedimethanol and 1,4-cyclohexanediethanol, and aliphatic polyhydric alcohols such as trimethylolpropane and pentaerythritol.

[0068] Furthermore, the copolymerized polyester contains terephthalic acid as the main dicarboxylic acid component, but may also contain aromatic dicarboxylic acids such as isophthalic acid, naphthalene-1,4- or -2,6-dicarboxylic acid, 5-sodium sulfisoisophthalic acid, 4,4'-diphenyldicarboxylic acid, and diphenylsulfodicarboxylic acid as dicarboxylic acid copolymer components; and aliphatic dicarboxylic acids such as glutaric acid, adipic acid, sebacic acid, azelaic acid, oxalic acid, and succinic acid. Among these, isophthalic acid is preferred from the viewpoint of the effects of this disclosure.

[0069] The copolymerized polyester preferably has a glass transition temperature of 35°C to 100°C. The inclusion of the copolymerized components described above lowers the glass transition temperature compared to polyethylene terephthalate, improving the film quality of the protective layer. On the other hand, if the glass transition temperature is too low, the heat resistance may be poor. A preferred glass transition temperature is 65°C to 90°C. Note that the glass transition temperature is calculated according to a standard method using a differential scanning calorimeter from the inflection point of the endothermic peak associated with the glass transition.

[0070] In one embodiment, the protective layer further comprises an isocyanate compound in addition to the copolymerized polyester. The inclusion of the isocyanate compound in the protective layer improves its heat resistance.

[0071] An isocyanate compound, for example, has two or more isocyanate groups in its molecule. Known compounds such as diisocyanate compounds with two isocyanate groups, or polyisocyanate compounds with three or more isocyanate groups, can be used as isocyanate compounds. The isocyanate compound may be aromatic or aliphatic, and may be either a low-molecular-weight or high-molecular-weight compound. The isocyanate compound may also be a blocked isocyanate compound obtained by an addition reaction using a known isocyanate blocking agent by a known and conventional method.

[0072] The isocyanate groups in the isocyanate compound react with hydroxyl groups present at the ends of the copolymerized polyester, causing the isocyanate compound to crosslink the copolymerized polyesters and form a higher polymer resin. As a result, the heat resistance of the protective layer is expected to improve.

[0073] Specific examples of isocyanate compounds include tetramethylene diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, metaxylylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, or trimers of these isocyanate compounds, and excess amounts of these isocyanate compounds reacted with low molecular weight active hydrogen compounds such as ethylene glycol, propylene glycol, metaxylylene alcohol, 1,3-bishydroxyethylbenzene, 1,4-bishydroxyethylbenzene, trimethylolpropane, glycerol, pentaerythritol, erythritol, sorbitol, ethylenediamine, monoethanolamine, diethanolamine, triethanolamine, metaxylylenediamine and their alkylene oxide adducts, various polyester resins, polyether polyols, polyamides, etc. to obtain adducts, burettes, allophanates, etc. In particular, the isocyanate compound is preferably at least one selected from the group consisting of metaxylylene diisocyanate and isophorone diisocyanate.

[0074] In the protective layer, the blending ratio of the isocyanate compound to the copolymer polyester (isocyanate compound / copolymer polyester) is preferably 1 / 3500 or more by mass, more preferably 1 / 3000 or more, even more preferably 1 / 2500 or more, even more preferably 1 / 2000 or more, and particularly preferably 1 / 1500 or more. By increasing the blending amount of the isocyanate compound to a certain level or higher, the heat resistance of the protective layer is improved. Furthermore, in the protective layer, the blending ratio of the isocyanate compound to the copolymer polyester (isocyanate compound / copolymer polyester) is preferably 1 / 1 or less by mass, more preferably 1 / 5 or less, even more preferably 1 / 100 or less, even more preferably 1 / 500 or less, and particularly preferably 1 / 700 or less. By keeping the amount of isocyanate compound below a certain level, it is possible to prevent the protective layer from becoming cloudy and losing its transparency.

[0075] The protective layer may contain additives to the extent that they do not impair the properties of the present disclosure. Examples of additives include oxygen absorbers, plasticizers, ultraviolet absorbers, ultraviolet stabilizers, antioxidants, color inhibitors, matting agents, deodorants, flame retardants, weathering agents, antistatic agents, thread friction reducers, slip agents, mold release agents, antioxidants, ion exchange agents, and colorants. These additives can be used individually or in combination of two or more.

[0076] The protective layer may be a single layer or a multilayer structure of two or more layers. Furthermore, if the protective layer is multilayer, each layer may have the same composition or a different composition.

[0077] The thickness of the protective layer is preferably 0.5 μm to 1000 μm, and more preferably 0.7 μm to 500 μm. The thickness of the protective layer can be measured, for example, on the body of the preform. The thickness of the protective layer refers to the thickness of the cross-section at the point where the thickness of the protective layer's cross-section is smallest. If the protective layer is multi-layered, the thickness of the protective layer is the sum of the thicknesses of all layers.

[0078] <Preform manufacturing method> Next, an embodiment of the method for manufacturing the preform of this disclosure will be described.

[0079] The preform 30 shown in Figure 1 is first manufactured by injection molding the above-mentioned support-forming material using a conventionally known apparatus to create a support 37 having a mouth portion 31, a body portion 32, and a bottom portion 33. Next, the outside of the support 37 is subjected to a surface treatment. That is, the method for manufacturing a preform according to the present disclosure includes a step of performing a surface treatment on the outside of the support. The surface treatment is a pre-treatment or pre-treatment performed before forming the barrier layer 38 on the preform 30. Examples of surface treatments include corona treatment, UV ozone treatment, plasma treatment, or flame treatment. Next, a coating solution containing a carboxyl group-containing resin, a polyvinyl alcohol-based resin, and a solvent is prepared. In the coating solution, the carboxyl group-containing resin and the polyvinyl alcohol-based resin react to obtain a reaction product. Next, the coating solution containing the above-mentioned reaction product is applied to the body 32 and bottom 33 of the support 37 after surface treatment to form a coating film. Next, by drying the coating film and removing the solvent, a barrier layer 38 is formed on the outside of the support 37, and the preform 30 shown in Figure 1 can be manufactured. That is, the method for manufacturing a preform according to this disclosure includes a step of applying a surface treatment to the outside of the support, followed by a step of forming a barrier layer on the outside of the support.

[0080] (Corona treatment) Corona treatment can typically be performed by applying a high voltage between a grounded dielectric coating roll and electrodes placed at regular intervals from the dielectric coating roll to generate a corona discharge, and then passing a support between the discharging electrodes and the dielectric coating roll. Corona treatment is usually performed on the outside of the support, but is not limited to this, and may be performed on both the outside and inside of the support.

[0081] Examples of dielectric-coated rolls include those in which the roll core is made of iron or aluminum, and the dielectric is made of silicon, hyperon, EPT, or ceramic.

[0082] The gap (clearance) between the dielectric coating roll and the electrode is preferably 2.5 mm or less, more preferably 2.0 mm or less, and even more preferably 1.6 mm or less.

[0083] Corona treatment is usually performed in an atmospheric environment, but it may also be performed in an inert gas atmosphere such as nitrogen gas. The discharge rate as a treatment condition is set appropriately, and is usually 40 W·min / m². 2 The above is preferable, preferably 43 W·min / m 2 More than 80W min / m 2 The following is more preferable: 48 W·min / m 2 More than 80W min / m 2 The following applies: The discharge amount can be calculated using the following formula (1), where L (m) is the length of the discharge electrode, V (m / min) is the speed of the support, and P (W) is the discharge power. Discharge amount = P / (L×V) Formula (1)

[0084] The discharge power is preferably 100W or more, more preferably 150W or more, and even more preferably 200W or more.

[0085] When corona treatment is performed in an atmospheric environment, applying a high voltage causes corona discharge between the electrode and the support, generating ozone. The ozone absorbs the discharge energy, generating oxygen radicals. These oxygen radicals oxidize the thermoplastic resin and other materials that make up the support, forming carbonyl groups, carboxyl groups, hydroxyl groups, etc.

[0086] Corona-treated surfaces have an increased number of functional groups such as carbonyl groups, carboxyl groups, and hydroxyl groups compared to untreated surfaces, and the wettability index according to JIS K 6768:1999 is usually 40 mN / m or higher, preferably 43 mN / m or higher, and more preferably 45 mN / m or higher.

[0087] (UV ozone treatment) UV ozone treatment refers to a process in which an object to be treated is irradiated with UV (ultraviolet) light in the air, converting oxygen in the air into ozone, and modifying the object with ozone and UV light. The wavelength of UV light is preferably 270 nm or less, more preferably 210 nm or less, and even more preferably 180 nm or less. As an example, the wavelength of UV light is 254 nm, 185 nm, or 172 nm. Short-wavelength UV light is irradiated onto the object to be treated (e.g., support 37) located at a short distance from the UV lamp.

[0088] Short-wavelength UV light ozonates oxygen in the atmosphere and attenuates the UV light itself, so it is preferable to keep the distance between the UV lamp and the object being treated close. The distance between the UV light source and the object being treated is preferably 10 mm or less, more preferably 5 mm or less, and even more preferably 2 mm or less.

[0089] The irradiation intensity of UV light from the UV lamp is preferably 50 W / cm². 2 More preferably, 100 W / cm² 2 More preferably, 150 W / cm² 2 That's all.

[0090] The UV lamp may also be an excimer lamp that emits excimer UV light. In this case, the UV ozone treatment becomes an excimer treatment.

[0091] The UV ozone treatment may be applied to the entire outer surface of the support 37, or to a portion of the outer surface of the support 37.

[0092] (Plasma treatment) Plasma treatment is a method of surface treatment using plasma discharge. Plasma processing is not particularly limited, but examples include atmospheric pressure plasma processing and vacuum plasma processing. The plasma gas (process gas) used in plasma processing is not particularly limited, but examples include nitrogen gas, helium gas, argon gas, and mixed gases obtained by mixing these gases with one or more of oxygen gas, carbon dioxide gas, and hydrogen gas. The plasma processing speed is preferably 10 mm / second or more and 1500 mm / second or less, and more preferably 50 mm / second or more and 1000 mm / second or less. When performing plasma processing using a plasma discharge nozzle, the distance between the plasma discharge nozzle and the surface of the support is preferably 1 mm to 100 mm, and more preferably 5 mm to 50 mm.

[0093] (Frame processing) Flame treatment is a method of surface treatment using a flame. For frame processing, conventionally known methods such as using a burner can be used. The gas pressure for flame processing is preferably 0.005 MPa or more and 10 MPa or less, and more preferably 0.01 MPa or more and 1.5 MPa or less. The frame processing speed is preferably 100 mm / second or more and 2000 mm / second or less, and more preferably 200 mm / second or more and 1000 mm / second or less. When performing flame processing using a burner, the distance between the burner and the surface of the support is preferably 10 mm to 600 mm, and more preferably 20 mm to 400 mm.

[0094] (Coating liquid) The solvent used in the coating solution must be capable of dissolving or emulsifying and dispersing the materials constituting the barrier layer. Examples of solvents include water; alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol, n-propyl alcohol, n-butyl alcohol, and n-pentyl alcohol; and polar organic solvents such as dimethyl sulfoxide, N,N-dimethylformamide, and N,N-dimethylacetamide. These solvents can be used individually or in combination of two or more. Preferably, the solvent used is water, alcohols, or a mixture thereof, and more preferably, a mixed solvent of water and isopropyl alcohol. This improves the viscosity of the coating solution, making it possible to reduce the number of coating applications and thus improve the productivity of container production.

[0095] In the coating solution, the total concentration of solids in the materials constituting the barrier layer is preferably 2% by mass or more and 15% by mass or less, and more preferably 3% by mass or more and 10% by mass or less. This allows for the formation of a barrier layer of uniform thickness.

[0096] The viscosity of the coating solution is preferably 150 mPa·s to 4000 mPa·s, and more preferably 200 mPa·s to 3000 mPa·s. This allows for further improvement in container productivity. The viscosity of the coating solution can be measured using a rotational viscometer at a temperature of 20°C, in accordance with JIS Z 8803:2011.

[0097] The coating solution can be applied by conventionally known methods. Examples of coating methods include applying the solution with a brush, immersing the container in the coating solution, and spraying the coating solution onto the surface of the container.

[0098] The drying temperature of the coating film formed from the coating liquid is a temperature at which the solvent can be removed. The drying temperature is preferably 20°C to 80°C, and more preferably 50°C to 70°C.

[0099] (Material for forming protective layer) In the method for manufacturing a preform according to this disclosure, if a protective layer is to be further formed on the outside of the barrier layer, the protective layer can be formed on the outside of the barrier layer by applying a protective layer forming material to the outside of the barrier layer after the barrier layer has been formed and then drying it. For example, by forming a protective layer on the preform 30 shown in Figure 1, the preform 30 shown in Figure 3 can be manufactured. The material used for forming the protective layer can be the same as the material used for the protective layer in the preform.

[0100] The protective layer-forming material may be dissolved in a solvent and applied. The solvent is not particularly limited as long as it can dissolve, emulsify, and disperse the protective layer-forming material. For example, water, acetone, methyl isobutyl ketone, methyl ethyl ketone, ethyl acetate, n-propyl acetate, methanol, ethanol, isopropanol, hexane, heptane, cyclohexane, methylcyclohexane, etc., can be used. Among these, ethyl acetate, methyl ethyl ketone, or a mixed solvent of ethyl acetate and methyl ethyl ketone is preferred because it can dissolve or emulsify and disperse the copolymerized polyester well.

[0101] The drying temperature when forming the protective layer is not particularly limited as long as it is a temperature at which the solvent can be removed, but it is preferably 20°C to 80°C, and more preferably 40°C to 70°C.

[0102] The preform 30 shown in Figure 2 can be manufactured in the same manner as described above by appropriately selecting the areas to be coated with the coating liquid. The preform 30 shown in Figure 4 can be manufactured in the same manner as described above by appropriately selecting the application locations for the coating liquid and protective layer forming material.

[0103] <Container> Next, a container manufactured by the container manufacturing method of this disclosure will be described. The container is formed by blow-molding the above-mentioned preform. This makes it possible to create a container with excellent recyclability and gas barrier properties. Examples of containers include bottles, vials, cups, trays, and packs.

[0104] The volume increase ratio of the container relative to the preform is preferably 2 to 45, more preferably 5 to 40, and even more preferably 8 to 35. By increasing the volume by more than double, the preform before blow molding can be made smaller. Furthermore, by limiting the volume increase rate to 45 times or less, the gas barrier properties of the container after blow molding can be further improved. The volume increase rate of the container relative to the preform is defined as "V2 / V1," where V1 is the volume of the preform excluding the mouth, and V2 is the volume of the container excluding the mouth after blow molding.

[0105] Figure 5 is a schematic half-cross-sectional view showing one embodiment of the container. As shown in Figure 5, the container 10 comprises a mouth portion 11, a neck portion 12 located below the mouth portion 11, a shoulder portion 13 located below the neck portion 12, a body portion 14 located below the shoulder portion 13, and a bottom portion 15 located below the body portion 14.

[0106] The opening 11 includes a threaded portion 16 to which a cap (not shown) is screwed, a hub 17 provided below the threaded portion 16, and a support ring 18 provided below the hub 17. The shape of the opening 11 may be a conventionally known shape.

[0107] The neck portion 12 is located between the support ring 18 and the shoulder portion 13 and has a substantially cylindrical shape with a nearly uniform diameter. The shoulder portion 13 is located between the neck portion 12 and the torso portion 14 and has a shape in which the diameter gradually increases from the neck portion 12 side towards the torso portion 14 side.

[0108] The body portion 14 has a cylindrical shape with a substantially uniform diameter overall. However, it is not limited to this, and the body portion 14 may have a polygonal cylindrical shape such as a square cylindrical shape or an octagonal cylindrical shape. Alternatively, the body portion 14 may have a cylindrical shape with a horizontal cross-section that is not uniform from top to bottom. Furthermore, the body portion 14 has a substantially flat surface without any irregularities, but it is not limited to this. For example, the body portion 14 may have irregularities such as panels or grooves formed on it.

[0109] The bottom portion 15 has a recess 19 located in the center and a contact portion 20 provided around the recess 19. The shape of the bottom portion 15 is not particularly limited and may have conventionally known bottom shapes (for example, a petaloid bottom shape or a round bottom shape).

[0110] As shown in Figure 5, the container 10 has a support 21 and a barrier layer 22. Also as shown in Figure 5, the mouth 11 is made up of the support 21, and the neck 12, shoulder 13, body 14 and bottom 15 are made up of the support 21 and the barrier layer 22. Also as shown in Figure 5, the barrier layer 22 is provided on the outside of the container 10 so as to surround it. The barrier layer 22 may be provided in one or more areas selected from the neck 12, shoulder 13, torso 14, and bottom 15, either entirely or partially.

[0111] In one embodiment, the container has a barrier layer provided over at least the entire outer surface of the body. This efficiently improves the gas barrier properties of the container. Preferably, the container has a barrier layer provided over at least the shoulder and the entire outer surface of the body.

[0112] In one embodiment, as shown in Figure 6, the container has a barrier layer 22 covering at least 0.4L to 0.6L of the entire outer surface, with the lower end of the mouth 11 being "0L" and the ground portion 20 being "1L". This efficiently improves the gas barrier properties of the container. Preferably, the container has a barrier layer covering at least 0.1L to 0.8L of the entire outer surface, and more preferably, the container has a barrier layer covering at least 0.05L to 0.95L of the entire outer surface.

[0113] As shown in Figures 7 and 8, the container 10 may have a protective layer 23 provided on the outside of the barrier layer 22.

[0114] The container 10 shown in Figure 7 has a mouth portion 11 made of a support 21, and the neck portion 12, shoulder portion 13, body portion 14, and bottom portion 15 are made of the support 21, a barrier layer 22, and a protective layer 23. In the neck portion 12, shoulder portion 13, body portion 14, and bottom portion 15, the barrier layer 22 is provided on the entire outer surface of the support 21 so as to surround the support 21. The protective layer 23 is provided on the entire outer surface of the barrier layer 22 so as to surround the barrier layer 22. The protective layer 23 may be provided over all or part of the neck portion 12, shoulder portion 13, torso portion 14 and / or bottom portion 15.

[0115] In the container 10 shown in Figure 8, when the lower end of the mouth 11 is defined as "0L" and the ground portion 20 as "1L", a barrier layer 22 and a protective layer 23 are provided over the entire outer area, at least 0.4L to 0.6L. This configuration allows for efficient improvement of gas barrier properties. Preferably, the container 10 is provided with a barrier layer 22 and a protective layer 23 over the entire outer surface area of ​​at least 0.1 L to 0.8 L, and more preferably, the barrier layer 22 and protective layer 23 over the entire outer surface area of ​​at least 0.05 L to 0.95 L.

[0116] The thickness of the container's cross-section is preferably 0.1 mm or more and 0.4 mm or less, and more preferably 0.15 mm or more and 0.3 mm or less. The thickness of the cross-section of the container can be measured, for example, in the body of the container having at least a support and a barrier layer, and refers to the thickness of the cross-section at the point where the cross-sectional thickness is smallest.

[0117] The capacity / weight of the container 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 setting the container's capacity / weight to 5 mL / g or more, the container's weight can be reduced. By limiting the container's capacity / weight to 50 mL / g or less, the container's strength can be improved.

[0118] The full capacity of the container may be, for example, 100 mL or more and 2000 mL or less. Preferably, the full capacity of the container is 280 mL or more and 750 mL or less. Furthermore, the container's full capacity may be large, for example, between 10L and 60L.

[0119] The container's support, barrier layer, and protective layer will be described below.

[0120] (Support) The material for the container support can be the same as the material for the support in the preform.

[0121] The container support may have a single-layer structure or a multilayer structure of two or more layers. Furthermore, if the support has a multilayer structure, each layer may have the same composition or different compositions.

[0122] The cross-sectional thickness of the container support is preferably 0.01 mm or more and 0.35 mm or less, and more preferably 0.05 mm or more and 0.25 mm or less. The thickness of the cross-section of the container's support can be measured at the body of the container, and refers to the thickness of the cross-section at the point where the thickness of the support's cross-section is smallest.

[0123] (Barrier layer) The barrier layer material for the container can be the same as the barrier layer material used in the preform.

[0124] The barrier layer of the container may be a single layer or a multilayer of two or more layers. Furthermore, if the barrier layer is multilayer, each layer may have the same composition or different compositions.

[0125] The thickness of the container's barrier layer is preferably 0.1 μm to 200.0 μm, and more preferably 5.0 μm to 50.0 μm. This further improves the gas barrier properties of the container. The thickness of the barrier layer of a container can be measured, for example, on the body of the container, and refers to the thickness of the cross-section at the point where the cross-sectional thickness of the barrier layer is smallest. Furthermore, if the barrier layer is multilayered, the thickness of the barrier layer is the sum of the thicknesses of all layers.

[0126] (protective layer) The protective layer material for the container can be the same as the protective layer material used in the preform.

[0127] The protective layer of the container may be a single layer or a multilayer of two or more layers. Furthermore, if the protective layer is multilayered, each layer may have the same composition or a different composition.

[0128] The thickness of the protective layer of the container is preferably 0.1 μm to 200.0 μm, and more preferably 0.7 μm to 70.0 μm. This further improves the degradation resistance of the barrier layer. The thickness of the protective layer of a container can be measured, for example, on the body of the container, and refers to the thickness of the cross-section at the point where the thickness of the protective layer's cross-section is smallest. Furthermore, if the protective layer consists of multiple layers, the thickness of the protective layer is the sum of the thicknesses of all the layers.

[0129] <Container manufacturing method> Next, an embodiment of the method for manufacturing the container of this disclosure will be described.

[0130] The method for manufacturing a container according to this disclosure comprises, in this order, the steps of: manufacturing a preform by the method for manufacturing a preform according to this disclosure; and manufacturing a container by blow molding the preform. For example, the container 10 shown in Figure 5 can be manufactured by blow molding the preform 30 shown in Figure 1. For example, the container 10 shown in Figure 6 can be manufactured by blow molding the preform 30 shown in Figure 2. For example, the container 10 shown in Figure 7 can be manufactured by blow molding the preform 30 shown in Figure 3. For example, the container 10 shown in Figure 8 can be manufactured by blow molding the preform 30 shown in Figure 4. Blow molding can be carried out by conventionally known methods. [Examples]

[0131] The present disclosure will now be described in more detail with reference to examples, but the present disclosure is not limited to these examples.

[0132] [Example 1] A support structure comprising a mouth section, a body section, and a base section was fabricated by melting pelletized polyethylene terephthalate (PET) and injecting it using an injection molding machine. The mouth section of the support structure was equipped with a screw section, a cap, and a support ring in that order from the top of the mouth section. An excimer lamp (product name: HPV-ST Series, manufactured by Ushio Inc.) was placed 2 mm from the outer surface of the body of the support, and UV light was irradiated at an irradiation intensity of 200 mW for 10 seconds over the entire outer circumference of the support, excluding the mouth, thereby performing excimer treatment, a type of UV ozone treatment, on the outside of the support.

[0133] Seven parts by mass of polyacrylic acid (product name: AS-58, number average molecular weight: 106,000), manufactured by Nippon Shokubai Co., Ltd., were added to 93 parts by mass of water while stirring, and then completely dissolved by heating at 80°C to obtain a 7% by mass aqueous solution of polyacrylic acid. Separately, 7 parts by mass of polyvinyl alcohol (product name: PVA-124, degree of polymerization: 2400, degree of saponification: 98% to 99%) manufactured by Kuraray Co., Ltd. was added to 93 parts by mass of water while stirring, and then completely dissolved by heating at 90°C to obtain a 7% by mass PVA aqueous solution. A coating solution (viscosity: 230 mPa·s (20℃)) was prepared by mixing an aqueous solution of polyacrylic acid and an aqueous solution of PVA at room temperature in a mass ratio of 1:1.

[0134] The coating solution was applied to the body and bottom of the support to form a coating film, which was then dried at 50°C for 30 minutes. This process of forming and drying the coating film was repeated a total of three times to form a barrier layer. In this way, the preform of Example 1 was prepared. In the preform of Example 1, the cross-sectional thickness of the body was 4 mm, and the thickness of the barrier layer of the body was 50 μm. The basis weight of the preform of Example 1 was 20.5 g.

[0135] [Example 2] The preform for Example 2 was prepared in the same manner as in Example 1, except that instead of excimer treatment on the outside of the body of the support, corona treatment was performed on the entire outer circumference of the support, excluding the mouth, using an AGI-021S manufactured by Kasuga Electric Co., Ltd., at an output of 200W for 2 seconds with a clearance of 2.0 mm. In the preform of Example 2, the cross-sectional thickness of the body was 4 mm, and the thickness of the barrier layer of the body was 50 μm. The basis weight of the preform of Example 2 was 20.5 g.

[0136] [Comparative Example 1] A preform for Comparative Example 1 was prepared in the same manner as in Example 1, except that the outside of the support was not subjected to excimer treatment. In the preform of Comparative Example 1, the cross-sectional thickness of the body was 4 mm, and the thickness of the barrier layer of the body was 50 μm. The basis weight of the preform of Comparative Example 1 was 20.5 g.

[0137] [Comparative Example 2] A preform for Comparative Example 2 was prepared in the same manner as for Comparative Example 1, except that a barrier layer was not formed on the body and bottom of the support. In the preform of Comparative Example 2, the cross-sectional thickness of the body was 3 mm. The basis weight of the preform of Comparative Example 2 was 20.5 g.

[0138] <Tape peel test> A tape with a width of 18 mm (product name: Cellophane Tape No. 29, manufactured by Nitto Denko Corporation) was attached to the body of each preform of Examples 1 and 2 and Comparative Example 1. Holding one end of the tape, the tape was peeled off in one swift motion at a 90° pulling angle. FT-IR analysis was performed on the surface after tape removal using a Fourier transform infrared spectrophotometer (product name: FT / IR-610, manufactured by JASCO Corporation) to determine whether the layer constituting the outer surface of the body after tape removal was a support layer or a barrier layer. The results are shown in Table 1.

[0139] <Evaluation of carbon dioxide barrier properties> The preforms of Examples 1 and 2 and Comparative Examples 1 and 2 were heated to 120°C, and biaxial stretch blow molding was performed in a blow molding die to produce a container with a capacity of 400 mL, having a mouth, neck, shoulder, body, and bottom. Using a carbonator Pilot Plant BPP-1 (product name, manufactured by Bixul Co., Ltd.), carbonated water at a liquid temperature of 5°C and a gas volume of 4.0 was filled into containers and capped. Under conditions of 22°C and 40% RH humidity, the gas volume inside the container was measured after 60 minutes using a DGV-1 (product name, manufactured by Bixul Co., Ltd.). The gas volume inside the container was similarly measured after 2 weeks, 4 weeks, 8 weeks, and 12 weeks. The carbon dioxide retention rates after 2 weeks, 4 weeks, 8 weeks, and 12 weeks were calculated using the following formula (2). The results are shown in Table 1. Carbon dioxide retention rate (%) = Gas volume after 2 weeks, 4 weeks, 8 weeks, or 12 weeks / Gas volume after 60 minutes × 100 ... Equation (2)

[0140] <Exterior Evaluation> After calculating the carbon dioxide retention rate after 12 weeks, the appearance of the container was evaluated based on the following criteria. The results are shown in Table 1. A: No carbon dioxide is trapped between the support and the barrier layer, and the appearance is good. B: Carbon dioxide is trapped between the support and the barrier layer, causing a defect in appearance.

[0141] [Table 1]

[0142] As is clear from Table 1, in Examples 1 and 2, the preforms manufactured by applying a surface treatment to the outside of the support body retained the barrier layer on the outer surface of the body even after tape peeling, and the barrier layer did not peel off from the support body in the tape peeling test. This indicates that the preforms in Examples 1 and 2 exhibit high adhesion between the support body and the barrier layer. Furthermore, in Examples 1 and 2, where a barrier layer was formed, the carbon dioxide retention rate was higher compared to Comparative Example 2, where no barrier layer was formed. This indicates that the containers made from the preforms of Examples 1 and 2 exhibit excellent carbon dioxide barrier properties. Furthermore, it can be seen that the containers made from the preforms of Examples 1 and 2 have a good appearance. [Explanation of Symbols]

[0143] 10: Container 11: Mouth 12: Neck 13:Shoulder 14: Torso 15: Bottom 16: Screw part 17: Kabura 18: Support Ring 19: Recess 20: Grounding part 21:Support 22: Barrier layer 23:Protective layer 30: Preform 31: Mouth 32: Torso 33: Bottom 34: Screw part 35: Kabura 36: Support Ring 37:Support 38: Barrier layer 39:Protective layer

Claims

1. A method for manufacturing a preform, comprising the steps of: applying a surface treatment to the outside of a support; and forming a barrier layer on the outside of the support, in this order, The preform comprises the support and the barrier layer provided on the outside of the support. A method for producing a preform, wherein the barrier layer comprises a carboxyl group-containing resin and a polyvinyl alcohol-based resin.

2. The method for manufacturing a preform according to claim 1, wherein the surface treatment is corona treatment, UV ozone treatment, plasma treatment, or flame treatment.

3. The method for manufacturing a preform according to claim 1, wherein the surface treatment is an excimer treatment.

4. A method for producing a preform according to any one of claims 1 to 3, wherein the mass ratio of the carboxyl group-containing resin to the polyvinyl alcohol-based resin is 1 / 20 or more and 10 / 1 or less.

5. A method for producing a preform according to any one of claims 1 to 3, wherein the carboxyl group-containing resin is polyacrylic acid.

6. A method for manufacturing a preform according to any one of claims 1 to 3, wherein the support comprises polyester.

7. A method for manufacturing a preform according to any one of claims 1 to 3, wherein the preform comprises a protective layer on the outside of the barrier layer.

8. The method for producing a preform according to claim 7, wherein the protective layer includes a copolymerized polyester.

9. The method for producing a preform according to claim 8, wherein the copolymerized polyester contains ethylene glycol and neopentyl glycol or propylene glycol as a diol component.

10. The method for producing a preform according to claim 8, wherein the copolymerized polyester contains terephthalic acid as a dicarboxylic acid component.

11. A method for manufacturing a container, comprising the steps of manufacturing a preform by the method for manufacturing a preform described in any one of claims 1 to 3, and manufacturing a container by blow molding the preform, in this order.

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