JP7769898B2 - Container and preform thereof - Google Patents

Description

The present invention relates to a container and its preform.

In recent years, recycling of used plastic containers has been promoted with the aim of reducing environmental impact, such as by cutting carbon dioxide emissions. Recycling must be done with the same type of material, so when recycling used PET bottles, for example, the collected bottles must be separated into labels, caps, and bottle bodies. Furthermore, if the bottle body has a multi-layer structure, for example, if it has a support body and a coating layer formed on the surface of the support body, it must be separated into the support body and the coating layer.

Patent Document 1 discloses a plastic bottle having a polyvinyl alcohol coating as a barrier layer on the outer surface of a support, and a polyvinyl butyral coating as a protective layer on top of the polyvinyl alcohol coating. Because polyvinyl alcohol is water-soluble, the barrier layer between the support and the protective layer of the plastic bottle disclosed in Patent Document 1 can be dissolved during recycling, allowing the support, barrier layer, and protective layer to be separated.

Patent No. 6037879

However, when recycling containers with a polyvinyl butyral coating as a protective layer, the separation performance between the container's support and the protective layer was insufficient, leaving room for improvement in the recyclability of the containers.

Accordingly, an object of the present invention is to provide a container with improved recyclability and a preform for such a container.

The inventors have now discovered that by using a specific material for the protective layer, the support and protective layer can be easily separated, improving the recyclability of the container.

Therefore, the present invention provides a container comprising a support, a protective layer provided on at least one surface of the support, and a barrier layer provided between the support and the protective layer,
the support comprises a thermoplastic resin;
the barrier layer is water-soluble or alkali-soluble;
The protective layer is a container containing a polymer component including an olefin-based monomer and an acrylic-based monomer.

In the container according to the present invention, the polymer component may further contain an aromatic vinyl monomer.

In the container according to the present invention, the olefin monomer may be one or more selected from the group consisting of ethylene and 2-methyl-1-butene.

In the container according to the present invention, the acrylic monomer may be one or more selected from the group consisting of n-butyl acrylate, methyl methacrylate, and n-butyl methacrylate.

In the container according to the present invention, the mass ratio of the acrylic monomer to the olefin monomer may be 1/2 or more and 3/1 or less.

In the container according to the present invention, the barrier layer may contain a polyvinyl alcohol-based resin.

In the container according to the present invention, the barrier layer may further contain a carboxyl group-containing resin.

In the container according to the present invention, the thickness of the protective layer may be 0.1 μm or more and 200 μm or less.

In the container according to the present invention, the thermoplastic resin may be polyester or polyolefin.

The present invention is a preform of the container.

The present invention provides a container with improved recyclability and a preform for such a container.

1 is a schematic half-sectional view showing one embodiment of a bottle, which is an example of a container of the present invention. 1 is a schematic half-sectional view showing one embodiment of a bottle, which is an example of a container of the present invention. 1 is a schematic half-sectional view showing one embodiment of a bottle, which is an example of a container of the present invention. 1 is a schematic half-sectional view showing an embodiment of a cup, which is an example of a container of the present invention. 1 is a schematic half-sectional view showing an embodiment of a preform, which is an example of a preformed article of the present invention. 1 is a schematic half-sectional view showing an embodiment of a preform, which is an example of a preformed article of the present invention. 1 is a schematic half-sectional view showing an embodiment of a preform, which is an example of a preformed article of the present invention.

<Container>
The container of the present invention comprises a support, a protective layer provided on at least one surface of the support, and a barrier layer provided between the support and the protective layer.
In this specification, the term "container" refers to a molded product that contains an article. Examples of containers include molded products such as compression molded products, injection molded products, blow molded products, and thermoformed products. Specific examples of containers include bottles, vials, cups, trays, and packs.

The following describes each component that may be included in the container of the present invention.

(Support)
In the container of the present invention, the support is capable of maintaining the shape of the container and contains a thermoplastic resin. Examples of thermoplastic resins contained in the support include polyolefins such as polyethylene and polypropylene, polyesters such as polycarbonate, polyvinyl chloride, and polyethylene terephthalate, polyamides such as nylon 6 and nylon 6,6, and mixtures thereof. Among these, polyesters and polyolefins are preferred from the viewpoint of moldability, and polyesters are particularly preferred from the viewpoints of gas barrier properties, strength, and adhesion to the barrier layer.

In this specification, the term "polyester" refers to a polymer formed by ester bonds. Such polyesters are generally 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, dodecanedioic acid, eicosanedioic acid, pimelic acid, azelaic acid, methylmalonic acid, ethylmalonic acid, adamantanedicarboxylic acid, norbornenedicarboxylic acid, cyclohexanedicarboxylic acid, decalindicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 5-sodiumsulfoisophthalic acid, phenylendanedicarboxylic acid, anthracenedicarboxylic acid, phenanthrenedicarboxylic acid, 9,9'-bis(4-carboxyphenyl)fluorene acid, and ester derivatives thereof.
Examples of diol compounds include ethylene glycol, 1,2-propanediol, 1,3-propanediol, butanediol, 2-methyl-1,3-propanediol, hexanediol, neopentyl glycol, cyclohexanedimethanol, cyclohexanediethanol, decahydronaphthalenedimethanol, decahydronaphthalenediethanol, norbornanedimethanol, norbornanediethanol, tricyclodecanedimethanol, tricyclodecaneethanol, tetracyclododecanedimethanol, tetracyclododecanediethanol, decalindimethanol, decalindiethanol, and 5-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, pentaerythritol, and bis-β-hydroxyethyl terephthalate (BHET).
The polyester is preferably polyethylene terephthalate or modified polyethylene terephthalate obtained by polymerizing raw material monomers of polyethylene terephthalate with copolymerizable monomers.

The polyester may contain monomers other than dicarboxylic acid compounds and diol compounds as long as the properties of the present invention are not impaired. However, the content of such monomers is preferably 10 mol % or less, more preferably 5 mol % or less, and even more preferably 3 mol % or less, based on the total structural units.

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

The polyester may be not only virgin polyester but also recycled polyester from the viewpoint of reducing the environmental load. In this specification, "virgin polyester" means polyester that has not been recycled, and "recycled polyester" means polyester that has been recycled by collecting used products such as containers that have been shipped to the market.
Examples of recycled polyester include polyester obtained by decomposing recovered 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 recovered used products to remove contaminants and foreign matter, obtaining flakes, and then further treating the flakes at high temperature and under reduced pressure for a certain period of time to remove contaminants from within the resin (hereinafter referred to as "mechanically recycled polyester"). Mechanically recycled polyester may contain two or more catalysts. In this case, the mechanically recycled polyester may contain, for example, two or more of Sb-catalyzed polyester, Mn-catalyzed polyester, Ti-catalyzed polyester, Al-catalyzed polyester, Li-catalyzed polyester, and Ge-catalyzed polyester.

It is known that mechanically recycled polyester differs from virgin polyester and chemically recycled polyester in the content of antimony (Sb), sodium (Na), calcium (Ca), and/or magnesium (Mg). Specifically, mechanically recycled polyester is known to contain Sb in a proportion of 20 mg/L to 54 mg/L, Na in a proportion of 12 mg/L or more, Ca in a proportion of 4 mg/L or more, and/or Mg in a proportion of 2.5 mg/L or more. Therefore, mechanically recycled polyester can be distinguished from virgin polyester and chemically recycled polyester depending on whether the polyester satisfies one or more of these content proportions.
In addition, in the mechanically recycled polyester, the Sb element content is preferably 25 mg/L or more and 50 mg/L or less, the Na element content is preferably 14 mg/L or more, the Ca element content is preferably 4.5 mg/L or more, and the Mg element content is preferably 3 mg/L or more.

When the support contains mechanically recycled polyester, 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, per 100 parts by mass of the total amount of resin materials contained in the support.

From the standpoint 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.

The support may contain additives as long as they do not impair the properties of the present invention. Examples of additives include oxygen absorbers, plasticizers, UV stabilizers, antioxidants, matting agents, deodorizers, flame retardants, weather resistance agents, antistatic agents, friction reducers, slip agents, mold release agents, antioxidants, and ion exchange agents. These additives can be used alone or in combination of two or more.

The support may have a single-layer structure or a multi-layer structure of two or more layers. Furthermore, if the support has a multi-layer structure, each layer may have the same composition or different compositions as long as the properties of the present invention are not impaired.

The cross-sectional thickness of the 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 cross-sectional thickness of the support can be measured, for example, at the body of the container. The cross-sectional thickness of the support means the point where the cross-sectional thickness is thinnest.

The support is preferably surface-treated. Examples of surface treatments include corona treatment, low-temperature plasma treatment, and flame treatment. Such surface treatments improve the wettability of the support surface, thereby improving adhesion between the support and the layer in contact with the support.

(Barrier layer)
The barrier layer is a layer that has gas barrier properties. A container having such a barrier layer can prevent the permeation of gases such as oxygen, thereby preventing deterioration of the contents.

In the container according to the present invention, the barrier layer is water-soluble or alkali-soluble. This allows the container to be highly recyclable. The reasons for this are as follows:

When recycling used containers, the containers are first crushed into flakes and then washed with a liquid such as water and an alkaline solution. If a water-soluble or alkali-soluble barrier layer is present between the support and the protective layer, the barrier layer dissolves during this washing process, allowing the protective layer to be peeled off from the support and the support to be separated. Therefore, such containers have excellent recyclability. The barrier layer may be a layer that is both water-soluble and alkali-soluble.
In this specification, "water-soluble" means that the barrier layer dissolves in distilled water at 20°C in an amount of 3% by mass or more, preferably 10% by mass or more, and more preferably 20% by mass or more.
In this specification, "alkali-soluble" means that the barrier layer dissolves in a 1.5% by mass aqueous solution of sodium hydroxide at 90°C to a degree of 3% by mass or more, preferably 10% by mass or more, and more preferably 20% by mass or more.

In one embodiment, the barrier layer contains a polyvinyl alcohol-based resin. Polyvinyl alcohol-based resins are water-soluble or alkali-soluble resins, and have high cohesive strength, making them highly effective at blocking oxygen and water vapor. By including a polyvinyl alcohol-based resin in the barrier layer, the barrier layer can be made water-soluble or alkali-soluble, and the gas barrier properties of the container can be improved.

In one embodiment, the barrier layer includes a carboxy group-containing resin and a polyvinyl alcohol-based resin.
As described above, by including a polyvinyl alcohol-based resin in the barrier layer, the barrier layer can be made water-soluble or alkali-soluble, and the gas barrier properties of the container can be improved.
Furthermore, by including a carboxy group-containing resin in the barrier layer, the water solubility or alkali solubility of the barrier layer is improved, thereby improving the recyclability of the container. Furthermore, the carboxy group of the carboxy group-containing resin forms hydrogen bonds with the "-OH" of the polyvinyl alcohol resin or the solvent of the coating liquid used to form the barrier layer (e.g., water, an organic solvent having a hydroxy group, etc.), thereby increasing the viscosity of the coating liquid. This allows the thickness of the barrier layer to be increased with fewer coating cycles, thereby improving the productivity of the container.

The following describes polyvinyl alcohol resins and carboxyl group-containing resins.

Polyvinyl alcohol resins (also known as "PVA resins") are resins that contain alcoholic hydroxy groups in the polymer structure. PVA resins are typically obtained by saponifying vinyl ester polymers.

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 alone or in combination of two or more.

Vinyl ester polymers may contain 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; methacrylic acid alkyl esters 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 itaconic acid alkyl esters. These monomers can be used alone or in combination of two or more.

The PVA-based resin may be one in which some of the vinyl alcohol units have been modified by reactions such as acetalization, etherification, acetoacetylation, and cationization.

The degree of polymerization of the PVA-based resin is preferably 1,000 or more and 4,000 or less, more preferably 1,500 or more and 3,500 or less, and even more preferably 2,000 or more and 3,000 or less.
The average degree of polymerization of the PVA resin can be measured in accordance with JIS K 6726:1994.

The saponification degree of the PVA-based resin is preferably 70 mol % or more and 99.9 mol % or less, more preferably 90 mol % or more and 99.5 mol % or less, and even more preferably 95 mol % or more and 99.5 mol % or less, from the viewpoints of excellent solubility in a solvent and excellent storage stability of the composition.
The degree of saponification of the PVA-based resin can be measured in accordance with JIS K 6726:1994.

The PVA-based resin preferably has an aqueous solution viscosity of 3 mPa·s or more and 70 mPa·s or less, more preferably 50 mPa·s or more and 68 mPa·s or less, and even more preferably 54 mPa·s or more and 66 mPa·s or less, when the PVA-based resin is dissolved in pure water to give a concentration of 4 mass %.
The viscosity of the coating liquid can be measured at a temperature of 20°C in accordance with JIS Z 8803:2011.

PVA-based resins can be used alone or in combination of two or more types.

The carboxyl group-containing resin can be an existing carboxyl group-containing resin. The existing carboxyl group-containing resin is a general term for resins containing a carboxyl group in the polymer structure. Examples of the carboxyl group-containing resin include homopolymers of carboxyl group-containing unsaturated monomers, copolymers of carboxyl group-containing unsaturated monomers, copolymers of carboxyl group-containing unsaturated monomers with other polymerizable monomers, and polysaccharides containing carboxyl groups in the molecule (also referred to as "acidic polysaccharides"). These carboxyl group-containing resins can be used alone or in combination of two or more.
The carboxy group includes not only a free carboxy group but also an acid anhydride group (specifically, a dicarboxylic acid anhydride group). The acid anhydride group may be partially ring-opened to form a carboxy group. In the carboxy group-containing resin, some of the carboxy groups may be neutralized with an alkali.

The carboxyl group-containing unsaturated monomer is preferably an α,β-monoethylenically unsaturated carboxylic acid. Therefore, carboxyl group-containing resins include 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. Examples of other polymerizable monomers include ethylenically unsaturated monomers.

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 anhydrides such as maleic anhydride and itaconic anhydride. These acids can be used alone 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.

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 carboxylic acid vinyl esters such as vinyl acetate; alkyl acrylate esters such as methyl acrylate and ethyl acrylate; alkyl methacrylate esters 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 itaconic acid esters. These monomers can be used alone or in combination of two or more.

Carboxy group-containing polysaccharides include, for example, acidic polysaccharides that have a carboxy group in the molecule, such as alginic acid, carboxymethyl cellulose, and pectin. These acidic polysaccharides can be used alone or in combination of two or more. Acidic polysaccharides can also be used in combination with (co)polymers of α,β-monoethylenically unsaturated carboxylic acids.

When the carboxyl group-containing resin used in the present invention is a copolymer of an α,β-monoethylenically unsaturated carboxylic acid and another ethylenically unsaturated monomer, the composition of the copolymer preferably contains α,β-monoethylenically unsaturated carboxylic acid monomers in an amount of 60 mol% or more, more preferably 80 mol% or more, and even more preferably 90 mol% or more.

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

The carboxyl group-containing resin is preferably selected from one or more of polyacrylic acid, polymethacrylic acid, and maleic acid polymer. The carboxyl group-containing resin is preferably polyacrylic acid, which is relatively easy to obtain and has good recyclability and gas barrier properties.

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.

In the barrier layer, the content of the polyvinyl alcohol-based resin is preferably 20% by mass or more and 99% by mass or less, more preferably 30% by mass or more and 98% by mass or less, and even more preferably 40% by mass or more and 95% by mass or less, based on all components contained in the barrier layer.
By setting the content of the polyvinyl alcohol-based resin to 20% by mass or more, the gas barrier properties of the container can be further improved.
By setting the content of the polyvinyl alcohol-based resin to 99% by mass or less, the recyclability of the container can be further improved.

[0044] When the barrier layer contains a carboxy group-containing resin and a vinyl alcohol-based resin, the content of the carboxy group-containing resin 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, based on all components contained in the barrier layer.
By setting the content of the carboxyl group-containing resin to 1% by mass or more, the recyclability of the container can be further improved.
By setting the content of the carboxyl group-containing resin to 80% by mass or less, the gas barrier properties of the container can be further improved.

When the barrier layer contains a carboxy group-containing resin and a vinyl alcohol-based resin, the mass ratio of the carboxy group-containing resin to the polyvinyl alcohol-based resin (carboxy 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 mass ratio to 1/20 or more, the recyclability of the container can be further improved, and by setting the mass ratio to 10/1 or less, the gas barrier properties of the container can be further improved.
The above mass ratio is a solid content ratio.

The barrier layer may contain additives as long as they do not impair the properties of the present invention. Examples of additives include oxygen absorbers, plasticizers, UV stabilizers, antioxidants, matting agents, deodorizers, flame retardants, weather resistance agents, antistatic agents, thread friction reducers, slip agents, mold release agents, antioxidants, and ion exchange agents. These additives can be used alone or in combination of two or more.

The barrier layer may be a single layer or a multi-layer consisting of two or more layers. Furthermore, if the barrier layer is multi-layered, each layer may have the same composition or different compositions.

The thickness of the barrier layer is preferably 0.1 μm or more and 200 μm or less, and more preferably 1 μm or more and 50 μm or less.
The thickness of the barrier layer can be measured, for example, at the body of the container. The thickness of the barrier layer means the thinnest part. If the barrier layer has multiple layers, the thickness of the barrier layer is the sum of the thicknesses of all the layers.

The barrier layer may be colored in colors such as red, blue, yellow, green, brown, reddish-brown, orange, black, and white, and may be transparent or opaque. By coloring the barrier layer, it can absorb light that enters the container from the outside, such as sunlight, and suppress changes in the taste and color of the contents of the container, just as it would if the barrier layer were colored. Because it can effectively absorb visible light with wavelengths of 400 nm or more and 500 nm or less, the barrier layer is preferably colored in colors such as reddish-brown or orange. The barrier layer can be colored using, for example, a colorant.

(protective layer)
The protective layer is intended to protect the barrier layer. By providing the protective layer to the container, deterioration of the barrier function due to physical factors such as damage or peeling of the barrier layer, or chemical factors such as moisture absorption or dissolution, can be suppressed during the manufacture and use of the container.

In the container according to the present invention, the protective layer contains a polymer component including an olefin-based monomer and an acrylic monomer. In the present invention, the "polymer component" may be a polymer in which the above-mentioned monomers are copolymerized, or a mixture containing polymers in which each monomer is polymerized. Furthermore, when the polymer is a copolymer of monomers, it may be a random copolymer or a block copolymer.

It is preferable that the polymer component further contains an aromatic vinyl monomer. For example, the polymer component constituting the protective layer may be a mixture of a homopolymer of an olefin monomer, a homopolymer of an acrylic monomer, and a homopolymer of an aromatic vinyl monomer, or a copolymer of an olefin monomer, an acrylic monomer, and an aromatic vinyl monomer. Alternatively, it may be a mixture of a homopolymer of an olefin monomer and a copolymer of an acrylic monomer and an aromatic vinyl monomer, a mixture of a homopolymer of an acrylic monomer and a copolymer of an olefin monomer and an aromatic vinyl monomer, or a mixture of a homopolymer of an aromatic vinyl monomer and a copolymer of an acrylic monomer and an olefin monomer.

The olefin-based monomers and acrylic-based monomers contained in the polymer components that make up the protective layer, as well as the aromatic vinyl-based monomers that may be included if desired, are described below.

The polymer component constituting the protective layer may contain two or more types of olefin-based monomers. In this case, the two or more types of olefin-based monomers may be contained in the same polymer or in different polymers.

Examples of the olefin monomer include α-olefins such as ethylene, propylene, 1-butene, 2-methyl-1-butene, 3-methyl-1-butene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-octene, 1-heptene, 1-hexene, 1-decene, and 1-dodecene. Among these, one or more selected from the group consisting of ethylene and 2-methyl-1-butene are preferred.
The polymer of an olefin-based monomer may be a homopolymer of one type of olefin-based monomer or a copolymer of two or more types of olefin-based monomers. Specific examples of the polymer of an olefin-based monomer include polyethylene such as low-density polyethylene, medium-density polyethylene, and high-density polyethylene, polypropylene, poly-1-butene, poly-3-methyl-1-butene, poly-4-methyl-1-pentene, poly-3-methyl-1-pentene, ethylene-propylene copolymer, ethylene-1-butene copolymer, propylene-1-butene copolymer, and propylene-1-butene-ethylene copolymer.
Other examples of polymers of olefin-based monomers include copolymers of α-olefins with conjugated or non-conjugated dienes, such as ethylene-butadiene copolymers and ethylene-ethylidenenorbornene copolymers.
Other examples of polymers of olefin-based monomers include copolymers of two or more α-olefins with conjugated or non-conjugated dienes, such as ethylene-propylene-butadiene terpolymer, ethylene-propylene-dicyclopentadiene terpolymer, ethylene-propylene-ethylidenenorbornene terpolymer, and ethylene-propylene-1,5-hexadiene terpolymer.
Other examples of polymers of olefin-based monomers include copolymers of olefin-based monomers with other thermoplastic monomers. Specific examples of these include ethylene-vinyl acetate copolymers, ethylene-vinyl alcohol copolymers, and ethylene-unsaturated carboxylic acid copolymers. Examples of unsaturated carboxylic acids include methacrylic acid, acrylic acid, maleic acid, itaconic acid, crotonic acid, and fumaric acid.

The acrylic monomer may be an acrylic monomer having a polar functional group, or may be any other acrylic monomer.
The polymer component constituting the protective layer may contain two or more types of acrylic monomers. In this case, the two or more types of acrylic monomers may be contained in the same polymer or different polymers.

Specific examples of acrylic monomers having a polar functional group include hydroxyalkyl acrylates such as hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, and 4-hydroxybutyl acrylate, which have a hydroxy group; acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, and maleic acid, which have a carboxy group; glycidyl acrylate and glycidyl methacrylate, which have a glycidyl group; mono(2-methacryloyloxyethyl) acid phosphate and mono(2-acryloyloxyethyl) acid phosphate, which have a phosphoric acid group; acrylamide and methacrylamide, which have an amide group; and monomers having other functional groups such as acrylonitrile and methacrylonitrile.

Other acrylic monomers include acrylic acid esters and methacrylic acid esters. Specific examples include methyl acrylate, ethyl acrylate, n-butyl acrylate, i-butyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, 2-ethylhexyl methacrylate, and lauryl methacrylate. Of these, one or more selected from the group consisting of n-butyl acrylate, methyl methacrylate, and n-butyl methacrylate are preferred.

The polymer component constituting the protective layer may contain two or more types of aromatic vinyl monomers. In this case, the two or more types of aromatic vinyl monomers may be contained in the same polymer or in different polymers.

Specific examples of aromatic vinyl monomers include styrene and α-methylstyrene. Of these, styrene is preferred.

The container according to the present invention has a protective layer containing the polymer component containing the above-mentioned olefin-based monomer and acrylic monomer, which improves recyclability compared to conventional containers. The reasons for this are believed to be as follows:

The barrier layer of the container according to the present invention is a water-soluble or alkali-soluble layer. The water-soluble or alkali-soluble layer contains a resin having a polar group. Therefore, in the present invention, bonds or intermolecular forces are generated between the polar groups of the acrylic monomer contained in the polymer component constituting the protective layer and the polar groups in the barrier layer. For example, when the barrier layer contains a polyvinyl alcohol resin and the protective layer contains methyl methacrylate, hydrogen bonds are formed between the hydroxy groups of the polyvinyl alcohol resin and the ester groups of the methyl methacrylate. Due to such bonds and intermolecular forces, the protective layer and the barrier layer adhere strongly to each other.
The polyvinyl butyral (PVB) used in the protective layer of conventional containers is obtained by acetalizing the hydroxyl groups of polyvinyl alcohol (PVA) with butyraldehyde, and therefore contains almost no polar groups. Therefore, the adhesion between the protective layer and the barrier layer in conventional containers is lower than that between the protective layer and the barrier layer in containers according to the present invention. When the protective layer is strongly adhered to the barrier layer, as in the present invention, during the cleaning process for recycling the container, simultaneously with dissolution of the barrier layer, cleaning liquids such as water and alkaline solutions penetrate between the support and the barrier layer, which have a relatively low adhesion strength, causing peeling between the support and the barrier layer. As a result, the protective layer is thought to separate from the support while still in close contact with the barrier layer. On the other hand, since the adhesion between the protective layer and the barrier layer in conventional containers is not high, the protective layer is thought to separate from the support while peeled from the barrier layer. This difference in peeling mechanism is thought to ultimately result in improved recyclability of the container according to the present invention compared to conventional containers.
Furthermore, in the present invention, the polymer component constituting the protective layer contains an olefinic monomer together with an acrylic monomer, thereby maintaining durability, particularly water resistance. Specifically, the deterioration of water resistance due to the presence of an acrylic monomer having a polar group is reduced by the presence of the olefinic monomer, thereby maintaining the durability of the protective layer, such as water resistance.
As described above, in the present invention, the polymer component constituting the protective layer contains an olefin-based monomer and an acrylic-based monomer, thereby maintaining the durability of the protective layer and improving the recyclability of the container.
When the barrier layer contains a carboxy group-containing resin and a polyvinyl alcohol-based resin, the barrier layer contains carboxy groups from the carboxy group-containing resin in addition to hydroxy groups from the polyvinyl alcohol-based resin, and therefore the adhesion between the protective layer and the barrier layer is considered to be particularly excellent.

In the protective layer, the mass ratio of the acrylic monomer to the olefin monomer (acrylic monomer/olefin monomer) is preferably 1/2 or more and 3/1 or less, and more preferably 1/1 or more and 2/1 or less.
By setting the mass ratio to 1/2 or more, the recyclability of the container can be further improved.
By setting the mass ratio to 3/1 or less, the durability of the container can be further improved.
The above mass ratio is a solid content ratio.

The protective layer may contain additives as long as they do not impair the properties of the present invention. Examples of additives include oxygen absorbers, 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, and colorants. These additives can be used alone or in combination of two or more.

The protective layer may be a single layer or multiple layers consisting of two or more layers. Furthermore, if the protective layer is multiple layers, each layer may have the same composition or different compositions.

The thickness of the protective layer is preferably 0.5 μm or more and 1000 μm or less, more preferably 0.7 μm or more and 500 μm or less, and even more preferably 1 μm or more and 100 μm or less, thereby further improving the deterioration resistance of the barrier layer.
The thickness of the protective layer can be measured, for example, at the body of the container, and means the thinnest point. If the protective layer has multiple layers, the thickness of the protective layer is the sum of the thicknesses of all the layers.

The protective layer may be colored in colors such as red, blue, yellow, green, brown, reddish-brown, orange, black, and white, and may be transparent or opaque. Similar to coloring the barrier layer, a colored protective layer can absorb light, such as sunlight, that enters the container from the outside, thereby preventing changes in the taste and color of the contents of the container. Because the protective layer can effectively absorb visible light with wavelengths of 400 nm or more and 500 nm or less, it is preferably colored reddish-brown or orange. The protective layer can be colored using, for example, a colorant.

(evaporated film)
The container of the present invention may have a vapor-deposited film to further improve the gas barrier properties.

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, organosilicon compounds such as hexamethyldisiloxane, and hard carbon films such as diamond-like carbon (DLC) films.
The hard carbon film made of DLC is a hard carbon film also called an i-carbon film or a hydrogenated amorphous carbon film (aC:H), which is an amorphous carbon film mainly composed of ^SP3 bonds.

The thickness of the vapor-deposited film is not particularly limited, and can be, for example, 1 nm or more and 150 nm or less.
The thickness of the deposited film can be measured, for example, at the body of the container, and refers to the location where the thickness is the thinnest.

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

Below, we will explain one embodiment of the container structure according to the present invention, using a bottle and a cup as examples.

Figures 1 to 3 are schematic half-sectional views showing one embodiment of a bottle, which is an example of a container of the present invention. As shown in Figures 1 to 3, the bottle 10 has a mouth 11, a neck 12 located below the mouth 11, a shoulder 13 located below the neck 12, a body 14 located below the shoulder 13, and a bottom 15 located below the body 14.

The mouth portion 11 includes a threaded portion 16 onto which a cap (not shown) is screwed, a cap 17 provided below the threaded portion 16, and a support ring 18 provided below the cap 17. The shape of the mouth portion 11 may be any conventionally known shape.
In this specification, "upper" and "lower" refer to the upper and lower sides, respectively, of the bottle 10 or cup 30 when the bottle 10 or cup 30 is held upright (FIGS. 1 to 4).

The neck 12 is located between the support ring 18 and the shoulder 13, and has a generally cylindrical shape with a generally uniform diameter. The shoulder 13 is located between the neck 12 and the body 14, and has a shape whose diameter gradually increases from the neck 12 side toward the body 14 side.

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

The bottom 15 has a central recess 19 and a grounding portion 20 surrounding the recess 19. The shape of the bottom 15 is not particularly limited, and may have any conventionally known bottom shape (e.g., a petaloid bottom or a rounded bottom).

As shown in Figures 1 to 3, the bottle 10 includes a support 21 and a protective layer 23 provided on one side of the support 21. Also, as shown in Figures 1 to 3, the bottle 10 includes a barrier layer 22 between the support 21 and the protective layer 23.

In one embodiment, as shown in FIG. 1, the bottle 10 has a mouth 11 formed by a support 21, and a neck 12, shoulder 13, body 14, and bottom 15 formed by a support 21, a barrier layer 22, and a protective layer 23. As shown in FIG. 1, in the neck 12, shoulder 13, body 14, and bottom 15, the barrier layer 22 is provided on the entire outer surface of the support 21 so as to surround the support 21. As shown in FIG. 1, the protective layer 23 is provided on the entire outer surface of the barrier layer 22 so as to surround the barrier layer 22.

In one embodiment, as shown in FIG. 2, the bottle 10 has a mouth 11 and neck 12 formed by a support 21, and a shoulder 13, body 14, and bottom 15 formed by a support 21, a barrier layer 22, and a protective layer 23. As shown in FIG. 2, in the shoulder 13, body 14, and bottom 15, the barrier layer 22 is provided on the entire outer surface of the support 21 so as to surround the support 21. As shown in FIG. 2, the protective layer 23 is provided on the entire outer surface of the barrier layer 22 so as to surround the barrier layer 22.

In one embodiment, bottle 10 may not have barrier layer 22 and protective layer 23 in a range of 1 mm to 10 mm below the lower end of support ring 18. When filling bottle 10 with contents, the portion below the lower end of support ring 18 (such as neck 12) is grasped and transported, and if barrier layer 22 and protective layer 23 are provided in this portion, there is a risk of poor gripping. A bottle that does not have barrier layer 22 and protective layer 23 in a range of 1 mm to 10 mm below the lower end of support ring 18 can prevent such poor gripping. This range is preferably 2 mm to 5 mm.
This range is the distance from the bottom end of the support ring 18 in a direction perpendicular to a plane when the bottle 10 is standing on its own on the plane.

In one embodiment, the barrier layer 22 and the protective layer 23 may be provided on the entire or partial area of one or more regions selected from the neck portion 12 , the shoulder portion 13 , the body portion 14 and the bottom portion 15 .
In one embodiment, the bottle 10 is preferably provided with a barrier layer 22 and a protective layer 23 over the entire exterior of the body 14. More preferably, the bottle 10 is provided with a barrier layer 22 and a protective layer 23 over the entire exterior of the shoulder 13 and body 14.

In one embodiment, as shown in Figure 3, when the bottom end of the mouth portion 11 is defined as "0 L" and the ground portion 20 is defined as "1 L", the bottle 10 has the barrier layer 22 and the protective layer 23 provided over the entire outer area of at least 0.4 L to 0.6 L. This configuration can efficiently improve the gas barrier properties.
The bottle 10 preferably has a barrier layer 22 and a protective layer 23 over the entire outer area of at least 0.1 L to 0.8 L, and more preferably has a barrier layer 22 and a protective layer 23 over the entire outer area of at least 0.05 L to 0.95 L.

A barrier layer 22 and a protective layer 23 may be provided on the inside of the bottle 10 (not shown).
The bottle 10 may have a vapor-deposited film on at least one selected from the group including the inside and outside of the bottle 10 (not shown).

Figure 4 is a schematic half-sectional view showing a cup, which is one embodiment of a container of the present invention. As shown in Figure 4, the cup 30 has a mouth 31, a body 32 provided below the mouth 31, and a bottom 33 provided below the body 32.

The mouth portion 31 has a flange shape, but the shape of the mouth portion 31 is not particularly limited and may be any conventional shape.

The body 32 in Figure 4 has a cylindrical shape with a generally uniform diameter overall, but this is not limited to this. The body 32 may have a polygonal cylindrical shape, such as a square or octagonal cylindrical shape. Alternatively, the body 32 may have a cylindrical shape with a non-uniform horizontal cross section from top to bottom. Also, the body 32 in Figure 4 has a generally flat surface without any irregularities, but this is not limited to this. For example, the body 32 may have irregularities such as panels or grooves formed thereon.

The bottom 33 has a central recess 34 and a grounding portion 35 provided around the recess 34. The shape of the bottom 33 is not particularly limited, and may have any conventional bottom shape (e.g., a rounded bottom).

As shown in Fig. 4, the cup 30 has a mouth 31 formed of a support 36, and a body 32 and a bottom 33 formed of the support 36, a barrier layer 37, and a protective layer 38. As shown in Fig. 4, in the body 32 and the bottom 33, the barrier layer 37 is provided on the entire outer surface of the support 36 so as to surround the support 36.
In one embodiment, the barrier layer 37 and the protective layer 38 may be provided on the entire or partial area of one or more selected from the mouth portion 31 , the body portion 32 and the bottom portion 33 .

A barrier layer 37 and a protective layer 38 may be provided on the inside of the cup 30 (not shown).
The cup 30 may have a vapor-deposited film on at least one selected from the group including the inside and outside of the cup (not shown).

When placing items in the cup 30, the cup 30 is sealed using a lid material with gas barrier properties (not shown). This allows the cup to have gas barrier properties.

In one embodiment, the container of the present invention may be a blow-molded product of a preform. The preform may be a preform of the present invention described below. When the container of the present invention is a bottle, a preform may be used as the preform.

When the bottle is a blow-molded preform, the volume increase rate of the bottle relative to the preform is preferably 2 or more and 45 or less, more preferably 5 or more and 40 or less, and even more preferably 8 or more and 35 or less.
The volume increase rate of the bottle relative to the preform means the volume increase rate of the blow-molded portion, for example, the volume increase rate " _V2 / _V1 " when the volume of the preform excluding the mouth portion is _V1 and the volume of the bottle excluding the mouth portion after blow molding is _V2 .

The oxygen permeability of the bottle is preferably 0.100 cc/day·bottle·0.21 atm or less, more preferably 0.070 cc/day·bottle·0.21 atm or less, even more preferably 0.050 cc/day·bottle·0.21 atm or less, and even more preferably 0.040 cc/day·bottle·0.21 atm or less.
In this specification, the oxygen permeability is a value measured in accordance with JIS K 7126-2:2006 using an oxygen permeability measuring device (for example, OX-TRAN 2/20, manufactured by MOCON) under conditions of 23°C and 40% RH, and is a value obtained by measuring the entire bottle with the mouth closed with a jig and dividing the measured value by the surface area of the entire bottle excluding the mouth.

The cross-sectional thickness of the container of the present invention 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 cross-sectional thickness of the container can be measured, for example, at the body of the container having at least the support, the barrier layer, and the protective layer. The cross-sectional thickness of the container means the point where the cross-sectional thickness is thinnest.

The container of the present invention preferably has a volume/mass of 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 volume/mass of the container to 5 mL/g or more, the weight of the container can be reduced.
Furthermore, by setting the volume/mass of the container to 50 mL/g or less, the strength of the container can be improved.

The container of the present invention may have a full capacity of, for example, 100 mL or more and 2000 mL or less. The full capacity of the container is preferably 280 mL or more and 750 mL or less.
The container of the present invention may also be a large container having a full capacity of, for example, 10 L or more and 60 L or less.

In the container of the present invention, the transmittance of visible light having a wavelength of 400 nm or more and 500 nm or less is preferably 20% or less. This can suppress changes in the taste and color of the contents. In particular, when the contents is beer, the problem of odor caused by sunlight can be suppressed. The transmittance is more preferably 15% or less, even more preferably 5% or less, and even more preferably 1% or less. Such transmittance can be adjusted by appropriately coloring at least one layer selected from the group including the protective layer and the barrier layer.
The transmittance of visible light having a wavelength of 400 nm or more and 500 nm or less can be obtained by measuring the light transmittance of visible light wavelengths at 0.5 nm wavelength intervals using a spectrophotometer. As the spectrophotometer, an ultraviolet-visible spectrophotometer manufactured by Shimadzu Corporation can be used.
The transmittance of the container is measured, for example, in the body of the container having at least the support, the barrier layer, and the protective layer.

The container of the present invention may be printed on its surface. The image formed by printing is not particularly limited, and examples thereof include patterns and letters. From the viewpoint of not being affected by the color tone of the container, the printing is preferably performed on the outer surface of the container.
Printing can be carried out by a known method, such as inkjet printing, gravure printing, offset printing, flexographic printing, thermal transfer printing, silkscreen printing, pad printing, hot stamping, and cold stamping.
Furthermore, a printed container can be obtained by blow molding a printed preform.

<Container manufacturing method>
The method for manufacturing a container of the present invention will be described below using a bottle as an example.

In one embodiment, the bottle 10 shown in FIG. 1 can be manufactured by the following procedure.
First, a support 21 having a mouth portion 11, a neck portion 12, a shoulder portion 13, a body portion 14, and a bottom portion 15 is prepared by a conventionally known method.
Next, a coating liquid for the barrier layer containing the material for forming the barrier layer 22 and a solvent is prepared.
Next, the coating liquid for the barrier layer is applied to the neck portion 12, shoulder portion 13, body portion 14 and bottom portion 15 of the support 21 to form a coating film.
The coated film is then dried to remove the solvent, thereby forming the barrier layer 22 .
Next, a coating liquid for the protective layer containing the material for forming the protective layer 23 and a solvent is prepared.
Next, the protective layer coating liquid is applied to the surface of the barrier layer 22 to form a coating film.
Next, the coating film is dried to remove the solvent, thereby forming the protective layer 23, and the bottle 10 shown in FIG. 1 can be manufactured.
The bottle 10 shown in FIGS. 2 and 3 can be manufactured by appropriately selecting the locations where the barrier layer coating liquid and the protective layer coating liquid are to be applied.

In one embodiment, the bottle 10 shown in Figures 1 to 3 can be manufactured by blow molding the preform 40 shown in Figures 5 to 7, which will be described later. Blow molding can be performed using a conventionally known method.

The solvent used in the coating solution for the barrier layer is one that can dissolve or emulsify and disperse the materials that make up the barrier layer. Examples of the solvent 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 alone or in combination of two or more.
The solvent is preferably water, an alcohol, or a mixture thereof, and more preferably a mixed solvent of water and isopropyl alcohol, which improves the viscosity of the coating solution for the barrier layer and reduces the number of coating cycles, thereby improving the productivity of the container.

In the coating solution for the barrier layer, the total solids concentration of 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 with a uniform thickness.

The viscosity of the coating liquid for the barrier layer is preferably 150 mPa·s or more and 4000 mPa·s or less, and more preferably 200 mPa·s or more and 2500 mPa·s or less, which can further improve the productivity of the container.
The viscosity of the coating liquid for the barrier layer can be measured using a rotational viscometer at a temperature of 20°C in accordance with JIS Z 8803:2011.

The barrier layer coating liquid can be applied by a conventional method. Examples of application methods include applying the coating liquid with a brush, immersing the container in the barrier layer coating liquid, and spraying the barrier layer coating liquid onto the surface of the container.

The drying temperature for the coating film formed from the barrier layer coating liquid is a temperature at which the solvent can be removed. The drying temperature is preferably 20°C or higher and 80°C or lower, more preferably 40°C or higher and 70°C or lower, and even more preferably 50°C or higher and 70°C or lower.

The solvent used in the protective layer coating solution is not particularly limited as long as it can dissolve or emulsify and disperse the protective layer-forming materials. For example, water, acetone, ethyl methyl ketone, methyl isobutyl ketone, ethyl acetate, n-propyl acetate, methanol, ethanol, isopropanol, hexane, heptane, cyclohexane, methylcyclohexane, etc. can be used. Of these, a mixed solvent of n-propyl acetate and methylcyclohexane is preferred as the solvent used in the protective layer coating solution, as it can dissolve or emulsify and disperse the polymer components well.

The protective layer coating liquid can be applied by a conventionally known method. Examples of application methods include applying the liquid using a brush, immersing the container in the protective layer coating liquid, and spraying the protective layer coating liquid onto the surface of the container.

The drying temperature for the coating film formed from the protective layer coating liquid is a temperature at which the solvent can be removed. The drying temperature is preferably 40°C or higher and 80°C or lower, and more preferably 50°C or higher and 70°C or lower.

The method for manufacturing a container of the present invention may include a step of printing images such as patterns and letters on the surface of the container.
Printing can be carried out by a known method. Examples of printing methods include inkjet printing, gravure printing, offset printing, flexographic printing, thermal transfer printing, silkscreen printing, pad printing, hot stamping, and cold stamping. For example, when printing by inkjet printing, UV-curable ink is applied to the container, and then irradiated with UV light to cure the ink. Alternatively, printing may be carried out using a thermal transfer sheet.

<Preform>
As described above, the container of the present invention can also be produced by forming a barrier layer and a protective layer on the surface of a support obtained by various methods such as compression molding, injection molding, blow molding, and thermoforming. However, particularly when the support is obtained by blow molding, a barrier layer and a protective layer can be formed on the surface of the support of a preform before blow molding, and the preform can then be blow molded to form a container. In this specification, the term "preform" refers to a molded body before blow molding the container of the present invention, and is used to produce the container of the present invention. The shape of the preform can be appropriately selected depending on the shape of the container after blow molding. The preform of the present invention comprises a support, a protective layer provided on at least one side of the support, and a barrier layer provided between the support and the protective layer.

The following describes each component of the preform of the present invention.

(Support)
In the preform of the present invention, the material constituting the support may be the same as the material constituting the support of the container of the present invention. By using such a material for the support, the container of the present invention can be obtained and a preform with excellent blow moldability can be obtained.

The support may have a single-layer structure or a multi-layer structure of two or more layers. If the support has a multi-layer structure, each layer may have the same composition or different compositions.

The cross-sectional thickness of the support is preferably 1.3 mm or more and 4.3 mm or less, and more preferably 1.9 mm or more and 2.9 mm or less.
The cross-sectional thickness of the support can be measured, for example, at the body of the preform, and refers to the location where the cross-sectional thickness is the thinnest.

The support of the preform is preferably surface-treated. Examples of surface treatments include corona treatment, low-temperature plasma treatment, and flame treatment. Such surface treatments improve the wettability of the support surface, thereby improving adhesion between the support and the layer in contact with the support.

(Barrier layer)
In the preform of the present invention, the material constituting the barrier layer can be the same as the material constituting the barrier layer of the container of the present invention. By using such a material for the barrier layer, the container of the present invention can be obtained and a preform with excellent blow moldability can be obtained.

The barrier layer is preferably a layer having light-blocking properties, gloss, color, gas barrier properties, etc., depending on the application of the container produced from the preform.
The barrier layer is particularly preferably a layer having gas barrier properties.

The barrier layer may be a single layer or two or more layers. Furthermore, if the barrier layer is multilayered, each layer may have the same composition or different compositions.

The thickness of the barrier layer is preferably 2 μm or more and 1000 μm or less, and more preferably 20 μm or more and 500 μm or less.
The thickness of the barrier layer can be measured, for example, at the body of the preform. The thickness of the barrier layer means the thinnest point. If the barrier layer has multiple layers, the thickness of the barrier layer is the sum of the thicknesses of all the layers.

The barrier layer may be colored in colors such as red, blue, yellow, green, brown, reddish-brown, orange, black, and white, and may be transparent or opaque. By using such a barrier layer, containers with a colored barrier layer can be manufactured. The barrier layer can be colored using, for example, a colorant.

(protective layer)
In the preform of the present invention, the material constituting the protective layer can be the same as the material constituting the protective layer of the container of the present invention. By using such a material for the protective layer, the container of the present invention can be obtained and a preform with excellent blow moldability can be obtained.

The protective layer may be a single layer or multiple layers consisting of two or more layers. Furthermore, if the protective layer is multiple layers, each layer may have the same composition or different compositions.

The thickness of the protective layer is preferably 0.5 μm or more and 1000 μm or less, more preferably 0.7 μm or more and 500 μm or less, and further preferably 10 μm or more and 300 μm or less from the viewpoint of blow moldability, such as being able to suppress cracking of the protective layer and barrier layer during blow molding.
The thickness of the protective layer can be measured, for example, at the body of the preform. The thickness of the protective layer means the thinnest point. If the protective layer has multiple layers, the thickness of the protective layer is the sum of the thicknesses of all the layers.

The protective layer may be colored in colors such as red, blue, yellow, green, brown, reddish-brown, orange, black, and white, and may be transparent or opaque. By using such a protective layer, containers with a colored protective layer can be manufactured. The protective layer can be colored using, for example, a colorant.

Below, we will explain one embodiment of the structure of a preform according to the present invention, using a preform as an example.

Figures 5 to 7 are schematic half-sectional views showing one embodiment of a preform according to the present invention. As shown in Figures 5 to 7, the preform 40 comprises a mouth 41, a body 42 connected to the mouth 41, and a bottom 43 connected to the body 42. Of these, the mouth 41 corresponds to the mouth 11 of the bottle 10 described below, and has substantially the same shape as the mouth 11. The body 42 corresponds to the neck 12, shoulder 13, and body 14 of the bottle 10, and has a substantially cylindrical shape. The bottom 43 corresponds to the bottom 15 of the bottle 10, and has a substantially hemispherical shape.

The mouth portion 41 includes a threaded portion 44 that corresponds to the threaded portion 16 of the bottle 10 (described below) onto which a cap (not shown) is screwed; a cap 45 that is provided below the threaded portion 44 and corresponds to the cap 17 of the bottle 10; and a support ring 46 that is provided below the cap 45 and corresponds to the support ring 18 of the bottle 10. The shape of the mouth portion 41 may be any conventional shape.

As shown in Figures 5 to 7, the preform 40 includes a support 47 and a protective layer 49 provided on one side of the support 47. Also, as shown in Figures 5 to 7, the preform 40 includes a barrier layer 48 between the support 47 and the protective layer 49.

In one embodiment, as shown in FIG. 5, the preform 40 has a mouth portion 41 formed by a support 47, and a body portion 42 and a bottom portion 43 formed by the support 47, a barrier layer 48, and a protective layer 49. As shown in FIG. 5, the barrier layer 48 is provided on the entire outer surface of the support 47 so as to surround the support 47. As shown in FIG. 5, the protective layer 49 is provided on the entire outer surface of the barrier layer 48 so as to surround the barrier layer 48.

In one embodiment, as shown in Fig. 6 , the preform 40 has a mouth portion 41 and a portion of the body portion 42 formed by a support 47, and the remaining portion of the body portion 42 and the bottom portion 43 formed by the support 47, a barrier layer 48, and a protective layer 49. As shown in Fig. 6 , the barrier layer 48 is provided on the entire outer surface of the support 47 so as to surround the support 47. As shown in Fig. 6 , the protective layer 49 is provided on the entire outer surface of the barrier layer 48 so as to surround the barrier layer 48.
In the above, "a part of the body 42" refers to the part corresponding to the neck 12 of the bottle 10 shown in Figure 2, and "the remaining part of the body 42" refers to the part corresponding to the shoulder 13, body 14, and bottom 15 of the bottle 10 shown in Figure 2.

In one embodiment, the preform 40 may not have a barrier layer 48 or a protective layer 49 in a range of 1 mm to 10 mm below the lower end of the support ring 46. This allows the manufacture of a bottle that is less likely to be gripped when transported while being filled with contents. This range is preferably 2 mm to 5 mm.

In one embodiment, the barrier layer 48 and the protective layer 49 may be provided over the entire or partial area in the vertical direction of at least one portion selected from the group including the body portion 42 and the bottom portion 43 .
7, when the lower end of the mouth portion 41 is defined as "0 L" and the lower end of the bottom portion 43 is defined as "1 L", the preform 40 has the barrier layer 48 and the protective layer 49 provided over the entire outer area of at least 0.4 L to 0.6 L. By configuring the preform in this way, a container with efficiently improved gas barrier properties can be obtained.
The preform 40 preferably has a barrier layer 48 and a protective layer 49 over the entire outer area of at least 0.2L to 0.7L, and more preferably has a barrier layer 48 and a protective layer 49 over the entire outer area of at least 0.1L to 0.9L.

A barrier layer 48 and a protective layer 49 may be provided on the inside of the preform 40 (not shown).

The cross-sectional thickness of the preform is preferably 1.4 mm or more and 4.5 mm or less, and more preferably 2 mm or more and 3 mm or less.
The cross-sectional thickness of the preform can be measured, for example, at the body of the preform having at least the support, the barrier layer, and the protective layer. The cross-sectional thickness of the preform means the point where the cross-sectional thickness is thinnest.

The preform of the present invention preferably has a transmittance of 20% or less for visible light having a wavelength of 400 nm or more and 500 nm or less. This allows the production of a container in which changes in the taste and color of the contents of the container are suppressed. The transmittance is more preferably 15% or less, even more preferably 5% or less, and even more preferably 1% or less. Such a transmittance can be adjusted by appropriately coloring at least one layer selected from the group including the protective layer and the barrier layer.
The transmittance of visible light having a wavelength of 400 nm or more and 500 nm or less can be obtained by measuring the light transmittance of visible light wavelengths at 0.5 nm wavelength intervals using a spectrophotometer. As the spectrophotometer, an ultraviolet-visible spectrophotometer manufactured by Shimadzu Corporation can be used.
The transmittance of the preform is measured, for example, in the body of the preform having at least the support, the barrier layer, and the protective layer.

The surface of the preform of the present invention may be printed. The image formed by printing is not particularly limited, and examples thereof include patterns and letters. From the viewpoint of not being affected by the color tone of the preform, the printing is preferably performed on the outer surface of the preform.
Printing can be carried out by a known method, such as inkjet printing, gravure printing, offset printing, flexographic printing, thermal transfer printing, silkscreen printing, pad printing, hot stamping, and cold stamping.

<Method of manufacturing preform>
The method for producing a preform according to the present invention will be described below with reference to an example of a preform.

In one embodiment, the preform 40 shown in FIG. 5 can be manufactured by the following procedure.
First, the material for forming the support is injection molded using a conventionally known device to produce the support 47 having the mouth portion 41, the body portion 42, and the bottom portion 43.
Next, a coating liquid for the barrier layer containing a material for forming the barrier layer 48 and a solvent is prepared.
Next, the coating liquid for the barrier layer is applied to the body portion 42 and the bottom portion 43 of the support 47 to form a coating film.
The coated film is then dried to remove the solvent, thereby forming the barrier layer 48 .
Next, a coating liquid for the protective layer containing the material for forming the protective layer 49 and a solvent is prepared.
Next, the protective layer coating liquid is applied to the surface of the barrier layer 48 to form a coating film.
Next, the coating film is dried to remove the solvent, thereby forming a protective layer 49, and the preform 40 shown in FIG. 5 can be manufactured.
The preform 40 shown in FIGS. 6 and 7 can be manufactured by appropriately selecting the locations to be coated with the barrier layer coating liquid and the protective layer coating liquid.

The coating fluid for the barrier layer and the coating fluid for the protective layer used in the method for manufacturing the preform can be the same as the coating fluid for the barrier layer and the coating fluid for the protective layer used in the method for manufacturing the container.

The coating fluid for the barrier layer and the coating fluid for the protective layer can be applied by conventional methods. Examples of coating methods include applying the coating fluid using a brush, immersing the preform in the coating fluid for the barrier layer, and spraying the coating fluid for the barrier layer onto the surface of the preform.

The method for producing a preform of the present invention may include a step of printing images such as patterns and letters on the surface of the preform.
Printing can be carried out by a known method. Examples of printing methods include inkjet printing, gravure printing, offset printing, flexographic printing, thermal transfer printing, silkscreen printing, pad printing, hot stamping, and cold stamping. For example, when printing by inkjet printing, UV-curable ink can be applied to the preform, and then irradiated with UV light to cure the ink. Alternatively, printing can be carried out using a thermal transfer sheet.

The present invention will now be described in more detail using examples, but the present invention is not limited to these examples.

[Example 1]
Pellets of polyethylene terephthalate (PET) were prepared.
The PET was melted and injected into an injection molding machine to produce a preform support having a mouth, a body, and a bottom. The mouth of the support had a screw portion, a cap, and a support ring in that order from above the mouth.

Next, 10.35 g of polyacrylic acid (manufactured by Nippon Shokubai Co., Ltd., product name: AS-58, number average molecular weight: 106,000) was dissolved in 239.7 g of water. Separately, 10.35 g of PVA (manufactured by Kuraray Co., Ltd., product name: PVA-124, degree of polymerization: 2400, degree of saponification: 98-99%) was dissolved in a mixed solvent of 227.7 g of water and 12.0 g of isopropyl alcohol (IPA). These solutions were mixed to prepare a barrier layer coating liquid (viscosity: 195.5 mPa·s (20°C)). This barrier layer coating liquid was applied to the body and bottom of the support to form a coating film, which was then dried at 50°C for 10 minutes. This coating film formation and drying process was repeated three times to form the barrier layer. The mass ratio (solids ratio) of polyacrylic acid to PVA was 1/1.

Next, a resin (polymer component) containing 26.7% by mass of ethylene, 11.0% by mass of 2-methyl-1-butene, 34.9% by mass of methyl methacrylate, 11.8% by mass of n-butyl acrylate and n-butyl methacrylate, and 15.6% by mass of styrene was dissolved in a mixed solvent of n-propyl acetate and methylcyclohexane to prepare a protective layer coating liquid. This protective layer coating liquid was applied to the surface of the barrier layer to form a coating film, which was then dried at 50°C for 10 minutes. This coating film formation and drying was repeated a total of three times to form a protective layer, resulting in a preform as shown in FIG. 5.
The cross-sectional thickness of the body of the preform was 3 mm, the barrier layer thickness was 50 μm, and the protective layer thickness was 110 μm. The weight of the preform was 18.3 g.

The preform was then heated to 110°C and biaxially stretched and blow-molded in a blow molding mold to produce a 500 mL bottle with a mouth, neck, shoulder, body, and bottom, as shown in Figure 1. The barrier layer and protective layer were formed on the outer surfaces of the bottle's neck, shoulder, body, and bottom. The cross-sectional thickness of the bottle's body was 0.2 mm, the barrier layer was 5 μm thick, and the protective layer was 10 μm thick.

[Comparative Example 1]
A preform was obtained in the same manner as in Example 1, except that a protective layer was formed by dissolving only polyvinyl butyral in ethyl acetate to prepare a protective layer coating liquid, and using this protective layer coating liquid, a coating film was formed and dried a total of seven times to form a protective layer.
The cross-sectional thickness of the body of the preform was 3 mm, the barrier layer was 50 μm thick, and the protective layer was 100 μm thick. The weight of the preform was 18.3 g.

Next, in the same manner as in Example 1, a bottle was obtained from the preform of this comparative example.
The cross-sectional thickness of the body of the bottle was 0.2 mm, the barrier layer was 5 μm thick, and the protective layer was 9 μm thick.

[Comparative Example 2]
A preform was obtained in the same manner as in Example 1, except that a protective layer was formed using a protective layer coating liquid (UNISTOR (registered trademark) XP04A manufactured by Mitsui Chemicals, Inc.) in which only an acid-modified polyolefin was dissolved in a mixed solvent of methylcyclohexane and ethyl acetate.
The cross-sectional thickness of the body of the preform was 3 mm, the barrier layer thickness was 50 μm, and the protective layer thickness was 110 μm. The weight of the preform was 18.3 g.

Next, in the same manner as in Example 1, a bottle was obtained from the preform of this comparative example.
The cross-sectional thickness of the body of the bottle was 0.2 mm, the barrier layer was 5 μm thick, and the protective layer was 10 μm thick.

<<Recyclability evaluation>>
The bottles obtained in the above Examples and Comparative Examples were crushed into flakes, which were then placed in a 1.5% by mass aqueous solution of sodium hydroxide at 90°C and stirred for 15 minutes. The recyclability of the bottles was evaluated based on the following criteria. The evaluation results are shown in Table 1. The recyclability evaluation was performed by mixing a small amount of red colorant into the protective layer coating liquid to color the protective layer.
(Evaluation criteria)
A: The support and the protective layer were completely separated in the aqueous solution.
B: In the aqueous solution, flakes were present in which the support and the protective layer were not separated.

10: Bottle 11: Mouth 12: Neck 13: Shoulder 14: Body 15: Bottom 16: Threaded portion 17: Turnip 18: Support ring 19: Recess 20: Ground portion 21: Support 22: Barrier layer 23: Protective layer 30: Cup 31: Mouth 32: Body 33: Bottom 34: Recess 35: Ground portion 36: Support 37: Barrier layer 38: Protective layer 40: Preform 41: Mouth 42: Body 43: Bottom 44: Threaded portion 45: Turnip 46: Support ring 47: Support 48: Barrier layer 49: Protective layer

Claims (7)

A container comprising a support, a protective layer provided on at least one surface of the support, and a barrier layer provided between the support and the protective layer,
the support comprises a thermoplastic resin;
the barrier layer is water-soluble or alkali-soluble;
the protective layer includes a polymer component including an olefin-based monomer and an acrylic-based monomer,
the olefin-based monomer is at least one selected from the group consisting of ethylene and 2-methyl-1-butene,
The thickness of the protective layer is 10 μm or more and 1000 μm or less . A container comprising a support, a protective layer provided on at least one surface of the support, and a barrier layer provided between the support and the protective layer,
the support comprises a thermoplastic resin;
the barrier layer is water-soluble or alkali-soluble;
the protective layer includes a polymer component including an olefin-based monomer and an acrylic-based monomer,
the acrylic monomer is at least one selected from the group consisting of n-butyl acrylate, methyl methacrylate, and n-butyl methacrylate;
The thickness of the protective layer is 10 μm or more and 1000 μm or less . 3. The container according to claim 1 , wherein a mass ratio of the acrylic monomer to the olefinic monomer is 1/2 or more and 3/1 or less. The container according to claim 1 , wherein the barrier layer comprises a polyvinyl alcohol-based resin. The container of claim 4 , wherein the barrier layer further comprises a carboxyl group-containing resin. 6. The container according to claim 1 , wherein the thermoplastic resin is a polyester or a polyolefin. A container preform according to any one of claims 1 to 6 .