JP7620869B2 - Containers and preforms 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 the environmental burden, such as by cutting carbon dioxide emissions. Recycling must be done with the same type of material, so for example, when recycling used PET bottles, the collected PET bottles must be separated into the label, cap, and bottle body. Furthermore, if the bottle body has a multi-layer structure, for example, if it has a support and a coating layer provided on the surface of the support, it must be separated into the support 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 the polyvinyl alcohol coating. Since 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, and as a result, the support, barrier layer, and protective layer can be separated.

Patent No. 6037879

However, in containers that have a polyvinyl alcohol coating as a barrier layer, the support and protective layer may not be completely separated when recycling the container, leaving room for improvement in terms of recyclability.

Therefore, the object of the present invention is to provide a container with excellent recyclability and a preform for such a container.

The present invention provides a container comprising a support, a protective layer provided on at least one surface side 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 a container containing a carboxyl group-containing resin and a polyvinyl alcohol-based resin.

In the container according to the present invention, the carboxyl group-containing resin may be polyacrylic acid.

In the container according to the present invention, the content of the carboxyl group-containing resin may be 1% by mass or more and 80% by mass or less based on the total components contained in the barrier layer.

In the container according to the present invention, the mass ratio of the carboxyl group-containing resin to the polyvinyl alcohol resin may be 1/20 or more and 10/1 or less.

In the container according to the present invention, the thickness of the barrier layer of the preform 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 at least one selected from the group including polyesters and polyolefins.

The present invention is a preform of the container.

The present invention provides a container with excellent recyclability and a preform for this container.

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

<Container>
The container of the present invention comprises a support, a protective layer provided on at least one surface side 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 body that contains an article. Examples of the container include molded bodies such as compression molded bodies, injection molded bodies, blow molded bodies, and thermoformed bodies. Specific examples of the container include bottles, vials, cups, trays, and packs.

Below, we will explain each component that the container of the present invention may have.

(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 the thermoplastic resin 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. From the viewpoint of moldability, the thermoplastic resin is preferably at least one selected from the group including polyesters and polyolefins.
The thermoplastic resin is preferably a polyester from the viewpoints of gas barrier properties, strength, and adhesion to the barrier layer, whereas the thermoplastic resin is preferably a polyolefin from the viewpoint of flexibility of the container.

In this specification, the term "polyester" refers to a polymer that is polymerized through ester bonds. Such polyesters are usually obtained by polycondensation of a dicarboxylic acid compound and a diol compound.
Examples of the dicarboxylic acid compound 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 the diol compound 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 a modified polyethylene terephthalate obtained by polymerizing a raw material monomer of polyethylene terephthalate and a copolymerizable monomer.

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.

The support may contain additives to the extent that the properties of the present invention are not impaired. Examples of additives include oxygen absorbers, plasticizers, UV stabilizers, antioxidants, matting agents, deodorants, flame retardants, weather resistance agents, antistatic agents, friction reducers, slip agents, release agents, antioxidants, and ion exchange agents. These additives may be used alone or in combination of two or more.

The support may be a single-layer structure or a multi-layer structure of two or more layers. In addition, when the support is a multi-layer structure, each layer may have the same composition or different compositions as long as the characteristics 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 the thinnest.

The support is preferably subjected to a surface treatment. Examples of surface treatments include corona treatment, low-temperature plasma treatment, and flame treatment. By performing such a surface treatment, the wettability of the support surface is improved, and the adhesion between the support and the layer in contact with the support can be improved.

(Barrier Layer)
In the container according to the present invention, the barrier layer contains a carboxyl group-containing resin and a polyvinyl alcohol-based resin. By providing such a barrier layer, the polyester container according to the present invention can improve recyclability while maintaining its barrier properties. The reason for this will be described below.

In recycling used containers, the containers are first crushed into flakes, and then washed with liquids such as water and an alkaline solution. If a water-soluble or alkaline-soluble layer is present between the support and the protective layer, this layer dissolves in the washing process, and the protective layer can be peeled off from the support to separate the support. Therefore, such containers have excellent recyclability.
Although polyvinyl alcohol resins are generally water-soluble resins, a layer consisting of only polyvinyl alcohol resins has insufficient solubility to separate the support and the protective layer in the washing step of recycling. In the container according to the present invention, the solubility of the layer can be improved by using a carboxyl group-containing resin, i.e., a resin having a functional group with higher polarity than a hydroxyl group, together with the polyvinyl alcohol resin in the barrier layer. As a result, the container according to the present invention has excellent recyclability.
In addition, polyvinyl alcohol resins have a high cohesive force and therefore have a high effect of blocking oxygen and water vapor. Therefore, a layer containing a polyvinyl alcohol resin has gas barrier properties. Since a carboxyl group-containing resin has excellent compatibility with a polyvinyl alcohol resin, even when used together with a polyvinyl alcohol resin, the gas barrier properties of the barrier layer can be prevented from being reduced.
As described above, by forming the barrier layer as a layer containing a carboxy group-containing resin and a polyvinyl alcohol-based resin, it is possible to obtain a container that has excellent recyclability while maintaining gas barrier properties.
Furthermore, by using a carboxyl group-containing resin, the carboxyl group of the carboxyl group-containing resin forms a hydrogen bond with the "-OH" of the polyvinyl alcohol resin or the solvent of the coating liquid used to form the barrier layer (e.g., water or an organic solvent having a hydroxyl group), 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 polyvinyl alcohol resin and carboxyl group-containing resin contained in the barrier layer are described below.

Polyvinyl alcohol resins (also called "PVA resins") are resins that contain alcoholic hydroxyl groups in the polymer structure. PVA resins are usually obtained by saponifying vinyl ester polymers.

Vinyl ester polymers are usually 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.

The vinyl ester polymer 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; 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; itaconic acid alkyl esters, and the like. 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 polymerization degree 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 further 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.

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

When the PVA-based resin is dissolved in pure water to give a concentration of 4 mass %, the viscosity of the resulting aqueous solution is preferably 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.
The viscosity of the aqueous solution 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 may be an existing carboxyl group-containing resin. The carboxyl group-containing resin is a general term for resins that contain a carboxyl group in the structure of the polymer. The carboxyl group-containing resin may be a homopolymer of a carboxyl group-containing unsaturated monomer, a copolymer of a carboxyl group-containing unsaturated monomer, a copolymer of a carboxyl group-containing unsaturated monomer and another polymerizable monomer, or a polysaccharide (also called an "acidic polysaccharide") that contains a carboxyl group in the molecule. These carboxyl group-containing resins may 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 become a carboxy group. In the carboxy group-containing resin, a part of the carboxy group may be neutralized with an alkali.

The carboxy group-containing unsaturated monomer is preferably an α,β-monoethylenically unsaturated carboxylic acid. Thus, the carboxy group-containing resin includes a homopolymer of an α,β-monoethylenically unsaturated carboxylic acid, a copolymer of two or more kinds of α,β-monoethylenically unsaturated carboxylic acids, and a copolymer of an α,β-monoethylenically unsaturated carboxylic acid and another polymerizable monomer. Examples of the other polymerizable monomer include an ethylenically unsaturated monomer.

Examples of the α,β-monoethylenically unsaturated carboxylic acid include unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, etc., unsaturated dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid, etc., unsaturated dicarboxylic anhydrides such as maleic anhydride, itaconic anhydride, etc. These acids can be used alone or in combination of two or more kinds.
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.

Examples of other polymerizable monomers, particularly ethylenically unsaturated monomers, copolymerizable with α,β-monoethylenically unsaturated carboxylic acids include ethylene; α-olefins such as propylene, 1-butene, 1-pentene, 1-hexene, and 1-octene; saturated carboxylic acid vinyl esters such as vinyl acetate; acrylic acid alkyl esters such as methyl acrylate and ethyl acrylate; 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; itaconic acid alkyl esters, etc. These monomers can be used alone or in combination of two or more.

Examples of carboxyl group-containing polysaccharides include acidic polysaccharides having a carboxyl group in the molecule, such as alginic acid, carboxymethylcellulose, and pectin. These acidic polysaccharides can be used alone or in combination of two or more. Acidic polysaccharides can 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 α,β-monoethylenically unsaturated carboxylic acid and other ethylenically unsaturated monomers, the composition of the copolymer is such that the composition of α,β-monoethylenically unsaturated carboxylic acid monomers is preferably 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.

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.
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 content of the carboxy group-containing resin is preferably from 1 mass % to 80 mass %, more preferably from 2 mass % to 70 mass %, and even more preferably from 5 mass % to 60 mass %, 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 property of the container can be further improved.

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 property 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.

The barrier layer may contain additives to the extent that the properties of the present invention are not impaired. Examples of additives include oxygen absorbers, plasticizers, UV stabilizers, antioxidants, matting agents, deodorants, flame retardants, weather resistance agents, antistatic agents, thread friction reducers, slip agents, release agents, antioxidants, and ion exchange agents. These additives may be used alone or in combination of two or more.

The barrier layer may be a single layer or a multi-layer of two or more layers. If the barrier layer is a multi-layer, 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 part where the thickness is the thinnest. When 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, dark brown, orange, black, and white, and may be transparent or opaque. The colored barrier layer can absorb visible light entering the container from the outside, such as sunlight, and suppress changes in the taste and color of the contents of the container. In particular, when the contents are beer, a container with such a barrier layer makes it difficult for visible light with a wavelength of 400 nm to 500 nm to pass through the container, suppressing the problem that the bitter components in the beer are decomposed by sunlight and 3-methyl-2-butene-1-thiol, which is a sunlight odor component, is generated. Since the barrier layer can effectively absorb visible light with a wavelength of 400 nm to 500 nm, it is preferably colored dark brown or orange. For example, a coloring agent can be used to color the barrier layer.

(Protective Layer)
In the container according to the present invention, the protective layer is for protecting 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 one embodiment, the protective layer contains a thermoplastic resin. Examples of the thermoplastic resin contained in the protective layer include polyolefins such as polyethylene and polypropylene, polyvinyl chloride, polystyrene, polyvinyl acetate, acrylic resins, polyacetal, polyester, polyurethane, and polyvinyl acetal. These thermoplastic resins can be used alone or in combination of two or more.

In one embodiment, the thermoplastic resin contained in the protective layer is preferably polyvinyl acetal from the viewpoint of adhesion to the barrier layer. The polyvinyl acetal is particularly preferably polybutyl butyral. Polyvinyl butyral is a polymer having a structural unit having a vinyl butyral group in the molecule. Among them, a polymer having at least a structural unit having a vinyl butyral group and a structural unit having a hydroxyl group, as represented by the following chemical formula (I), is preferable.

（化学式（Ｉ）において、「ｌ」は、ビニルブチラール基を有する構成単位のモル％であり、ブチラール化されたビニルアルコール由来の構成単位の合計のモル％で表される。「ｍ」はビニルアルコール由来の構成単位のモル％を表し、「ｎ」は、酢酸ビニル由来の構成単位のモル％を表す。ｌ及びｍはいずれも０よりも大きい数であり、ｎは０でもよい。）

(In chemical formula (I), "l" is the mol % of the constituent units having a vinyl butyral group, and is expressed as the mol % of the total of the constituent units derived from butyralized vinyl alcohol. "m" represents the mol % of the constituent units derived from vinyl alcohol, and "n" represents the mol % of the constituent units derived from vinyl acetate. Both l and m are numbers greater than 0, and n may be 0.)

Polyvinyl butyral is obtained by reacting polyvinyl alcohol (also called "PVA") with butyraldehyde to acetalize it. When acetalizing PVA, it is difficult to completely acetalize PVA, and hydroxyl groups remain partially irreversibly. Therefore, polyvinyl butyral resin contains hydroxyl groups.
In addition, PVA is usually produced by saponifying polyvinyl acetate, but since a small amount of acetyl group often remains during the saponification process in the production process of polyvinyl alcohol, polyvinyl butyral generally has some acetyl group or hydroxy group remaining irreversibly. Therefore, polyvinyl butyral usually contains acetyl group, and a polymer having a structural unit having a vinyl butyral group, a structural unit having an acetyl group, and a structural unit having a hydroxy group is preferably used.

From the viewpoint of durability of the protective layer, the polyvinyl butyral preferably has a butyralization degree of 50 mol % or more and 90 mol % or less, more preferably 60 mol % or more and 85 mol % or less, and even more preferably 65 mol % or more and 75 mol % or less.
The butyralization degree herein means a molar fraction obtained by dividing the amount of ethylene groups to which butyral groups are bonded by the total amount of ethylene groups in the main chain, and corresponds to the mole % (l) of the constituent units having a vinyl butyral group in chemical formula (I).

From the viewpoint of durability of the protective layer, the polyvinyl butyral preferably contains 10 mol % or more and 40 mol % or less of structural units having a hydroxyl group, i.e., structural units (m) derived from vinyl alcohol, more preferably 14.9 mol % or more and 34 mol % or less, and even more preferably 24.5 mol % or more and 31 mol % or less.

In polyvinyl butyral, the content of structural units having an acetyl group, i.e., structural units (n) derived from vinyl acetate, is preferably 10 mol % or less, more preferably 0.1 mol % or more and 6 mol % or less, and even more preferably 0.5 mol % or more and 4 mol % or less.

Polyvinyl butyral may further contain structural units obtained by reacting vinyl alcohol with an aldehyde other than butyraldehyde to form acetalized vinyl alcohol. The amount of such structural units is preferably 10 mol % or less.
In the chemical formula (I), the sum of l, m, and n is preferably 100 mol %.

From the viewpoint of durability of the protective layer, the number average molecular weight of the polyvinyl butyral is preferably 15,000 to 90,000, more preferably 20,000 to 70,000, and even more preferably 25,000 to 65,000.

When polyvinyl butyral is dissolved in 5% by mass aqueous ethanol to give a concentration of 10% by mass, the viscosity of the resulting aqueous solution is preferably 3 mPa·s or more and 300 mPa·s or less, more preferably 10 mPa·s or more and 280 mPa·s or less, and even more preferably 20 mPa·s or more and 260 mPa·s or less.
The viscosity of the aqueous solution can be measured using a falling ball viscometer at a temperature of 20° C. in accordance with JIS Z 8803:2011.

The glass transition temperature (Tg) of polyvinyl butyral is preferably 50° C. or more and 100° C. or less, and more preferably 60° C. or more and 80° C. or less, from the viewpoint of durability of the protective layer.
The glass transition temperature (Tg) can be obtained by measuring the change in heat quantity by DSC (differential scanning calorimetry) (DSC method).

In another embodiment, the thermoplastic resin contained in the protective layer is preferably polyurethane from the viewpoint of heat resistance and water resistance. Polyurethane can be obtained by a known method, and the manufacturing method is not limited. Polyurethane is, for example, a reaction product generated by reacting an organic polyol with an organic polyisocyanate (urethanization reaction).

The organic polyol may be a compound having a functional group number in one molecule of preferably 2 to 6, more preferably 2 to 4, and a number average molecular weight of preferably 500 to 100,000, more preferably 1,000 to 30,000. More specifically, polyester polyol, polyether polyol, polyether ester polyol, polyester amide polyol, acrylic polyol, polycarbonate polyol, polyhydroxyl alkane, polyurethane polyol, castor oil, or a mixture thereof (hereinafter, these may be referred to as organic polyol (1)). Among these, the organic polyol is preferably polyurethane polyol.
In the present specification, the number average molecular weight can be measured by gel permeation chromatography (GPC). In GPC measurement, the number average molecular weight of a polymer is generally measured in terms of standard polystyrene.

Examples of polyester polyols include polyester polyols obtained by reacting dibasic acids such as terephthalic acid, isophthalic acid, adipic acid, azelaic acid, and sebacic acid, or their dialkyl esters, or mixtures thereof, with glycols such as ethylene glycol, propylene glycol, diethylene glycol, butylene glycol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 3,3'-dimethylolheptane, polyoxyethylene glycol, polyoxypropylene glycol, and polytetramethylene ether glycol, or mixtures thereof. Examples of polyester polyols include polyester polyols obtained by ring-opening polymerization of lactones such as polycaprolactone, polyvalerolactone, and poly(β-methyl-γ-valerolactone).

Examples of polyether polyols include polyether polyols obtained by polymerizing oxirane compounds such as ethylene oxide, propylene oxide, butylene oxide, and tetrahydrofuran with low molecular weight polyols such as water, ethylene glycol, propylene glycol, trimethylolpropane, and glycerin as an initiator.

Examples of polyether ester polyols include polyether ester polyols obtained by reacting the above-mentioned polyether polyols with dibasic acids such as terephthalic acid, isophthalic acid, adipic acid, azelaic acid, and sebacic acid, or their dialkyl esters, or mixtures thereof.

Examples of polyesteramide polyols include polyesteramide polyols obtained by mixing an aliphatic diamine having an amino group, such as ethylenediamine, propylenediamine, or hexamethylenediamine, with the raw materials during the esterification reaction.

Examples of acrylic polyols include hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, etc., which contain one or more hydroxyl groups in one molecule, or acrylic polyols obtained by copolymerizing the corresponding methacrylic acid derivatives, etc., with, for example, acrylic acid, methacrylic acid, or their esters.

Examples of polycarbonate polyols include polycarbonate polyols obtained by reacting one or more glycols selected from ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,9-nonanediol, 1,8-nonanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, bisphenol A, and hydrogenated bisphenol A with dimethyl carbonate, diphenyl carbonate, ethylene carbonate, phosgene, etc.

The polyhydroxyalkane may be a liquid rubber obtained by copolymerizing butadiene or butadiene with acrylamide or the like.

The polyurethane polyol is a polyol having a urethane bond in one molecule, and examples thereof include polyurethane polyols obtained by reacting a polyol such as a polyether polyol, a polyester polyol, or a polyether ester polyol having a number average molecular weight of 200 to 20,000 with an organic polyisocyanate such that the ratio of isocyanate groups to hydroxyl groups (NCO/OH) is less than 1, preferably 0.9 or less.
In the polyurethane polyol, the polyol used is preferably a polyester polyol having a number average molecular weight of 200 to 20,000. Such a polyurethane polyol may be referred to as a polyester polyurethane polyol.

As the organic polyol, one having a carboxy group in its molecule (inside the molecule or at the molecular end) (hereinafter referred to as organic polyol (2)) can be used. The organic polyol (2) is preferably obtained by reacting the above organic polyol (1) with a polybasic acid or anhydride thereof. The organic polyol (1) used in this case contains two or more hydroxyl groups at the molecular end and has a number average molecular weight of preferably 1,000 to 100,000, more preferably 3,000 to 15,000.

Examples of polybasic acids or their anhydrides include aromatic polybasic acids such as phthalic acid, trimellitic acid, and pyromellitic acid, and their anhydrides, with their anhydrides, such as phthalic anhydride, trimellitic anhydride, and pyromellitic anhydride, being particularly suitable. In addition, derivatives derived from these anhydrides, such as ethylene glycol bisanhydrotrimellitate, glycerol trisanhydrotrimellitate, ethylene glycol bisanhydropyromellitate, and glycerol trisanhydropyromellitate, as well as abietic acid, a rosin component, and derivatives obtained by addition reaction of maleic anhydride with a C10H16 diene compound or a mixture thereof, can be used.

The synthesis of organic polyol (2) is carried out by adding a polybasic acid or its anhydride, preferably a polybasic acid anhydride, under heating after the synthesis of organic polyol (1). During the synthesis of the organic polyol, it is possible to obtain an organic polyol containing a carboxyl group inside or at the molecular end in one step from a polybasic carboxylic acid and a polyhydric alcohol.

The organic polyisocyanate has two or more isocyanate groups in one molecule. Examples of the organic polyisocyanate include aliphatic diisocyanates such as linear alkylene diisocyanates such as trimethylene diisocyanate, tetramethylene diisocyanate, and hexamethylene diisocyanate, and branched alkylene diisocyanates such as 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, and 2,2,4-trimethylhexamethylene diisocyanate. Isocyanates: alicyclic diisocyanates such as 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), methyl 2,4-cyclohexane diisocyanate, methyl 2,6-cyclohexane diisocyanate, 1,4-bis(isocyanatomethyl)cyclohexane, and 1,3-bis(isocyanatomethyl)cyclohexane; m-phenyl aromatic diisocyanates such as 1,3- or 1,4-xylylene diisocyanate or mixtures thereof, ω,ω'-diisocyanate, 1,5-naphthalene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4- or 2,6-tolylene diisocyanate or mixtures thereof, 4,4'-toluidine diisocyanate, dianisidine diisocyanate, 4,4'-diphenylether diisocyanate, etc.; aromatic aliphatic diisocyanates such as 1,4-diethylbenzene, 1,3- or 1,4-bis(1-isocyanato-1-methylethyl)benzene or mixtures thereof; organic triisocyanates such as triphenylmethane-4,4',4"-triisocyanate, 1,3,5-triisocyanatobenzene, 2,4,6-triisocyanatotoluene, and polyisocyanate monomers such as organic tetraisocyanates such as 4,4'-diphenyldimethylmethane-2,2'-5,5'-tetraisocyanate.
In addition to the above monomers, examples of organic polyisocyanates include dimers, trimers, biurets, and allophanates derived from the above polyisocyanate monomers; polyisocyanates having a 2,4,6-oxadiazinetrione ring obtained from carbon dioxide gas and the above polyisocyanate monomers; ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 3,3'-dimethylolpropane, cyclohexanedimethanol, diethylene glycol, triethylene glycol, and the like. Examples of the polyisocyanate monomer include adducts of low-molecular-weight polyols having a molecular weight of less than 200, such as ethylene glycol, dipropylene glycol, glycerol, trimethylolpropane, pentaerythritol, and sorbitol, and the above-mentioned polyisocyanate monomers; and adducts of polyester polyols, polyether ester polyols, polyester amide polyols, polycaprolactone polyols, polyvalerolactone polyols, acrylic polyols, polycarbonate polyols, polyhydroxy alkanes, castor oil, polyurethane polyols, and the like having a molecular weight of 200 or more and 20,000 or less, and the above-mentioned polyisocyanate monomers.
The organic polyisocyanates described above may be used alone or as a mixture of two or more kinds.
In one embodiment, the organic polyisocyanate is preferably an adduct as described above, more preferably an adduct of a monomeric polyisocyanate with a polyurethane polyol.

In the urethane reaction, at least one selected from the group including a silane coupling agent, a phosphorus oxyacid, and a derivative of a phosphorus oxyacid may be further used.

As the silane coupling agent, for example, those represented by the following chemical formula (II) or (III) can be used.
R-Si≡(X) ₃ ...(II)
R-Si≡(R')(X) ₂ ...(III)
In formulas (II) and (III), R represents an organic group having a vinyl group, an epoxy group, an amino group, an imino group or a mercapto group, R' represents a lower alkyl group, and X represents a methoxy group, an ethoxy group or a chlorine atom.
Examples of the silane coupling agent include chlorosilanes such as vinyltrichlorosilane, aminosilanes such as N-(dimethoxymethylsilylpropyl)ethylenediamine and N-(triethoxysilylpropyl)ethylenediamine, epoxysilanes such as γ-glycidoxypropyltrimethoxysilane and γ-glycidoxypropyltriethoxysilane, vinylsilanes such as vinyltriethoxysilane, etc. The amount of the silane coupling agent added is preferably 0.1% by mass or more and 5% by mass or less based on the polyurethane to be obtained.

Among the phosphorus oxygen acids or their derivatives, the phosphorus oxygen acid may be any one having at least one free oxygen acid, and examples thereof include phosphoric acids such as hypophosphorous acid, phosphorous acid, orthophosphoric acid, and hypophosphoric acid, and condensed phosphoric acids such as metaphosphoric acid, pyrophosphoric acid, tripolyphosphoric acid, polyphosphoric acid, and ultraphosphoric acid. Examples of derivatives of phosphorus oxygen acids include those obtained by partially esterifying the above phosphorus oxygen acids with alcohols while leaving at least one free oxygen acid. Examples of these alcohols include aliphatic alcohols such as methanol, ethanol, ethylene glycol, and glycerin, and aromatic alcohols such as phenol, xylenol, hydroquinone, catechol, and phloroglucinol. One or more types of phosphorus oxygen acids or their derivatives may be used. The amount of phosphorus oxygen acid or its derivative added is preferably 0.01% by mass to 10% by mass, more preferably 0.05% by mass to 5% by mass, and even more preferably 0.1% by mass to 1% by mass, based on the polyurethane obtained.

In one embodiment, the polyurethane is a polyurethane polyol, preferably a reaction product of a polyurethane polyol having a carboxy group in the molecule and an organic polyisocyanate. The organic polyisocyanate is preferably an adduct of a polyisocyanate monomer and a polyurethane polyol. By making the polyurethane into such a reaction product, the heat resistance of the container can be further improved.

In one embodiment, the polyurethane may be a reaction product of a polyester polyol and two or more organic polyisocyanates. At least one of the two or more organic polyisocyanates may be a linear alkylene diisocyanate. The linear alkylene diisocyanate may be hexamethylene diisocyanate.

The protective layer may contain additives to the extent that the properties of the present invention are not impaired. Examples of additives include oxygen absorbers, plasticizers, UV stabilizers, antioxidants, coloring inhibitors, matting agents, deodorants, flame retardants, weather resistance agents, antistatic agents, thread friction reducers, slip agents, release agents, antioxidants, ion exchange agents, and colorants. These additives may be used alone or in combination of two or more.

The protective layer may be a single layer or a multi-layer of two or more layers. If the barrier layer is a multi-layer, 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, and more preferably 0.7 μm or more and 500 μm or less, so that the deterioration resistance of the barrier layer can be further improved.
The thickness of the protective layer can be measured, for example, at the body of the container, and means the thinnest point. When 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 coloring the protective layer, it is possible to absorb light that enters the container from the outside, such as sunlight, as in the case of coloring the barrier layer, and to suppress changes in the taste and color of the contents of the container. The protective layer is preferably colored in reddish brown or orange, etc., since it can effectively absorb visible light with a wavelength of 400 nm or more and 500 nm or less. The protective layer can be colored, for example, using a coloring agent.

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

Examples of the vapor-deposited film include vapor-deposited films composed 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 DLC (Diamond Like Carbon) 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 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 a conventional method, for example, physical vapor deposition methods (PVD method) such as vacuum deposition, sputtering, and ion plating, as well as chemical vapor deposition methods (CVD method) such as plasma chemical vapor deposition, thermal chemical vapor deposition, and photochemical vapor deposition.

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 provided below the mouth 11, a shoulder 13 provided below the neck 12, a body 14 provided below the shoulder 13, and a bottom 15 provided below the body 14.

The mouth portion 11 includes a threaded portion 16 to 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 a 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 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 rectangular cylindrical shape or an octagonal cylindrical shape. Alternatively, the body 14 may have a cylindrical shape with a horizontal cross section that is not uniform 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.

The bottom 15 has a recess 19 located in the center and a grounding portion 20 provided around 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 shape, a rounded bottom shape, etc.).

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. In addition, 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 of a support 21, and a neck 12, a shoulder 13, a body 14, and a bottom 15 formed of a support 21, a barrier layer 22, and a protective layer 23. As shown in FIG. 1, in the neck 12, the shoulder 13, the body 14, and the bottom 15, the barrier layer 22 is provided on the entire outer area 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 area of the barrier layer 22 so as to surround the barrier layer 22.

In one embodiment, as shown in FIG. 2, the mouth 11 and neck 12 of the bottle 10 are formed by the support 21, and the shoulder 13, body 14, and bottom 15 are formed by the support 21, the barrier layer 22, and the 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 area 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 area 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 gripping failure. A bottle that does not have barrier layer 22 and protective layer 23 provided in a range of 1 mm to 10 mm below the lower end of support ring 18 can prevent such gripping failure. This range is preferably 2 mm to 5 mm.
It should be noted that this range is the distance from the lower end of the support ring 18 in a direction perpendicular to a plane when the bottle 10 is standing 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 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 area 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 area of the shoulder 13 and body 14.

In one embodiment, as shown in Fig. 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. With this configuration, when the barrier layer 22 is a barrier layer, the gas barrier property can be efficiently improved.
The bottle 10 is preferably provided with 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 provided with 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 the 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 has a cylindrical shape with a generally uniform diameter overall, but is not limited to this, and may have a polygonal cylindrical shape such as a square cylindrical shape or an octagonal cylindrical shape. Alternatively, the body 32 may have a cylindrical shape with a horizontal cross section that is not uniform from top to bottom. Also, the body 32 in FIG. 4 has a generally flat surface without any irregularities, but is not limited to this. For example, the body 32 may have irregularities such as panels or grooves.

The bottom 33 has a recess 34 located in the center 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 shape, etc.).

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 area 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 entirety or a portion of one or more areas 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 include a deposited film on at least one selected from the group including the inside and outside of the cup (not shown).

When placing an item in the cup 30, the cup 30 is sealed using a lid material with gas barrier properties (not shown). This makes the cup gas-barrier.

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

In the bottle, the oxygen permeability 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, product name, manufactured by MOCON Corporation) under conditions of 23°C and humidity of 40% RH, and is a value measured over the entire bottle with the mouth portion sealed with a jig and divided by the surface area of the entire bottle excluding the mouth portion.

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 a body portion 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 the thinnest.

The container of the present invention has a volume/mass of 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 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.
Furthermore, the container of the present invention may be a large one having a full filling 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 are 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 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 wavelength intervals of 0.5 nm 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 applied to the outer surface of the container.
Printing can be carried out by a known method, such as an inkjet method, a gravure printing method, an offset printing method, a flexographic printing method, a thermal transfer method, a silk screen method, a pad method, a hot stamp method, or a cold stamp method.
Furthermore, a printed container can be obtained by blow molding a preform on which a print has been applied.

<Container manufacturing method>
The method for producing a container of the present invention will be described below with reference to 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, the shoulder portion 13, the body portion 14 and the 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 polyurethane 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 to which the barrier layer coating fluid and the protective layer coating fluid are 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 described below. Blow molding can be performed by a conventionally known method.

The solvent used in the coating liquid for the barrier layer is one that can dissolve or emulsify and disperse the material that constitutes 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, 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 concentration of the solids 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 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 coating liquid for the barrier layer can be applied by a conventional method. Examples of the coating method include a method of applying the coating liquid by a brush, a method of immersing a container in the coating liquid for the barrier layer, and a method of spraying the coating liquid for the barrier layer on the surface of a container.

The drying temperature of the coating film formed from the coating liquid for the barrier layer 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 liquid is not particularly limited as long as it can dissolve and emulsify/disperse the protective layer forming material, and examples of the solvent that can be used include water, acetone, ethyl methyl ketone, methyl isobutyl ketone, ethyl acetate, methanol, ethanol, and isopropanol. When polyol, polyisocyanate, and polyurethane are used as the protective layer forming material, the solvent is preferably acetone, ethyl methyl ketone, methyl isobutyl ketone, ethyl acetate, and the like.

The protective layer coating liquid can be applied by a conventional method. Examples of the coating method include a method of applying the coating liquid by a brush, a method of immersing a container in the protective layer coating liquid, and a method of spraying the protective layer coating liquid on the surface of a container.

The drying temperature of 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 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 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 performed by a known method. Examples of printing methods include inkjet printing, gravure printing, offset printing, flexographic printing, thermal transfer printing, silk screen printing, pad printing, hot stamping, and cold stamping. For example, when printing is performed by the inkjet method, a UV-curable ink is applied to the container, and then irradiated with UV light to harden the ink. Printing may also be performed using a thermal transfer sheet.

<Preform>
As described above, the container of the present invention can 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. In particular, 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 be blow molded to produce a container. In this specification, the preform is 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.

Below, we will explain 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 be a single layer structure or a multilayer structure of two or more layers. If the support is a multilayer 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 portion of the preform, and refers to the location where the cross-sectional thickness is the thinnest.

The support of the preform is preferably subjected to a surface treatment. Examples of surface treatments include corona treatment, low-temperature plasma treatment, and flame treatment. By performing such a surface treatment, the wettability of the support surface is improved, and the adhesion between the support and the layer in contact with the support can be improved.

(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 in 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-shielding properties, glossiness, color, gas barrier properties, etc., depending on the application of the container produced from the preform.
The barrier layer is particularly preferably a barrier layer having gas barrier properties.

The barrier layer may be a single layer or a multi-layer of two or more layers. If the barrier layer is a multi-layer, 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 part where the thickness is the thinnest. When 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 or 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 barrier layer, a container having a colored barrier layer can be manufactured. The barrier layer can be colored, for example, using a coloring agent.

(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 in 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 a multi-layer of two or more layers. If the protective layer is a multi-layer, 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, and more preferably 0.7 μm or more and 500 μm or less.
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 part where the thickness is the thinnest. When 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 forming such a protective layer, a container having a colored protective layer can be manufactured. The protective layer can be colored, for example, using a coloring agent.

Below, we will explain one embodiment of the structure of the 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 approximately 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 an approximately cylindrical shape. The bottom 43 corresponds to the bottom 15 of the bottle 10, and has an approximately hemispherical shape.

The mouth portion 41 has a threaded portion 44 that corresponds to the threaded portion 16 of the bottle 10 (described below) to 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 a conventionally known 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. In addition, 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 area 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 area 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 part of a 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 area 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 area 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 FIG. 2, and "the remaining part of the body 42" refers to the parts corresponding to the shoulder 13, the body 14, and the bottom 15 of the bottle 10 shown in FIG. 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 makes it possible to manufacture a bottle that is less likely to be gripped during transportation when filling it 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 "0L" and the lower end of the bottom portion 43 is defined as "1L", the preform 40 has a barrier layer 48 and a protective layer 49 provided over the entire outer area of at least 0.4L to 0.6L. By configuring the preform in this way, when the barrier layer 48 is a barrier layer, a container with efficiently improved gas barrier properties can be obtained.
The preform 40 is preferably provided with 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 provided with 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 a body portion 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 the thinnest.

In the preform 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 makes it possible to produce a container in which changes in 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 wavelength intervals of 0.5 nm 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 portion 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 an inkjet method, a gravure printing method, an offset printing method, a flexographic printing method, a thermal transfer method, a silk screen method, a pad method, a hot stamp method, and a cold stamp method.

<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 depicted in FIG. 5 can be manufactured by the following procedure.
First, the material constituting the support is injection molded using a conventionally known device to produce support 47 having mouth portion 41, body portion 42, and 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 a barrier layer 48 .
Next, a coating liquid for the protective layer containing polyurethane 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 which the barrier layer coating fluid and the protective layer coating fluid are applied.

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

The coating liquid for the barrier layer and the coating liquid for the protective layer can be applied by a conventional method. Examples of the coating method include a method of applying the coating liquid by a brush, a method of immersing a preform in the coating liquid for the barrier layer, and a method of spraying the coating liquid for the barrier layer on the surface of a preform.

The method for producing a preform of the present invention may include a step of printing images such as patterns and characters on the surface of the preform.
Printing can be performed by a known method. Examples of printing methods include inkjet printing, gravure printing, offset printing, flexographic printing, thermal transfer printing, silk screen printing, pad printing, hot stamping, and cold stamping. For example, when printing is performed by the inkjet method, printing can be performed by applying a UV-curable ink to the preform, irradiating it with UV light, and curing it. Printing may also be performed using a thermal transfer sheet.

The present invention will now be described in more detail with reference to the following 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 has a screw portion, a cap, and a support ring in this order from above the mouth.

Next, 1.88 g of polyacrylic acid (manufactured by Nippon Shokubai Co., Ltd., product name: AS-58, number average molecular weight: 106,000) was dissolved in 43.5 g of water. Separately, 18.82 g of PVA (manufactured by Kuraray Co., Ltd., product name: PVA-124, polymerization degree: 2400, saponification degree: 98-99%) was dissolved in a mixed solvent of 414.0 g of water and 21.8 g of isopropyl alcohol (IPA). These solutions were mixed to prepare a coating liquid for the barrier layer (viscosity: 263.4 mPa·s (20°C)). This coating liquid for the barrier layer was applied to the body and bottom of the support to form a coating film, and the coating film was dried at 50°C for 10 minutes. This coating film formation and drying were performed a total of five times to form the barrier layer. The mass ratio (solid content ratio) of polyacrylic acid to PVA was 1/10.

Next, 42.1 parts by mass of a base material of a urethane-based coating material (product name: EL-540) manufactured by Toyo-Morton Co., Ltd., 7.9 parts by mass of a curing agent, and 50 parts by mass of ethyl acetate were mixed to prepare a coating liquid for a protective layer. This coating liquid for a protective layer was applied to the surface of the barrier layer to form a coating film, and the coating film was dried at 50° C. for 10 minutes. This formation and drying of the coating film was repeated three times in total to form a protective layer, and a preform as shown in FIG. 5 was obtained.
The cross-sectional thickness of the body of the preform was 3 mm, the barrier layer was 200 μm, and the protective layer was 100 μm. The weight of the preform was 20 g.

The preform was then heated to 110°C and biaxially stretched and blow molded in a blow molding die to obtain a bottle with a capacity of 500 mL and including 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 neck, shoulder, body, and bottom of the bottle. The cross-sectional thickness of the bottle body was 0.2 mm, the barrier layer was 20 μm, and the protective layer was 10 μm.

[Example 2]
A preform was obtained in the same manner as in Example 1, except that a solution of 3.45 g of polyacrylic acid dissolved in 79.9 g of water and a solution of 17.25 g of PVA dissolved in a mixed solvent of 379.4 g of water and 20.0 g of IPA were mixed to prepare a coating liquid for a barrier layer (viscosity: 256.4 mPa·s (20° C.)). The mass ratio of polyacrylic acid to PVA was 1/5.
Next, in the same manner as in Example 1, a bottle was obtained from the preform of this example.

[Example 3]
A preform was obtained in the same manner as in Example 1, except that a solution of 6.90 g of polyacrylic acid dissolved in 159.8 g of water and a solution of 13.80 g of PVA dissolved in a mixed solvent of 303.5 g of water and 16.0 g of IPA were mixed to prepare a coating liquid for a barrier layer (viscosity: 230.1 mPa·s (20° C.)). The mass ratio of polyacrylic acid to PVA was 1/2.
Next, in the same manner as in Example 1, a bottle was obtained from the preform of this example.

[Example 4]
A preform was obtained in the same manner as in Example 1, except that a solution in which 10.35 g of polyacrylic acid was dissolved in 239.7 g of water was mixed with a solution in which 10.35 g of PVA was dissolved in a mixed solvent of 227.7 g of water and 12.0 g of IPA to prepare a coating liquid for a barrier layer (viscosity: 195.5 mPa·s (20° C.)). The mass ratio of polyacrylic acid to PVA was 1/1.
Next, in the same manner as in Example 1, a bottle was obtained from the preform of this example.

[Example 5]
Polypropylene (PP) in pellet form was prepared.
The PP was melted and injected into an injection molding machine to produce a cup support having a mouth, a body, and a bottom.

Then, the outer surfaces of the body and bottom of the support were subjected to a corona treatment.

Next, a barrier layer was formed on the corona-treated surface of the support using the same barrier layer coating liquid as in Example 1, and a protective layer was formed on the surface of the barrier layer using the same protective layer coating liquid as in Example 1, to produce a cup as shown in Figure 4.

[Comparative Example 1]
A preform was obtained in the same manner as in Example 1, except that the barrier layer and the protective layer were not formed on the support.

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 bottle body was 0.2 mm.

[Comparative Example 2]
A preform was obtained in the same manner as in Example 1, except that a coating liquid for a barrier layer was prepared by dissolving only PVA in water, and a coating film was formed and dried using this coating liquid for a barrier layer, a total of seven times, to form a barrier layer.
The cross-sectional thickness of the body of the preform was 3 mm, the barrier layer was 200 μm, and the protective layer was 100 μm. The weight of the preform was 20 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 bottle body was 0.2 mm, the barrier layer was 20 μm thick, and the protective layer was 10 μm thick.

<<Recyclability evaluation>>
The bottles and cups obtained in the above Examples and Comparative Examples were crushed into flakes, and the flakes were then placed in a 1.5% by mass aqueous sodium hydroxide solution at 90°C and stirred for 15 minutes. The flakes were then filtered off, and the alkaline aqueous solution on the flake surfaces was washed away with distilled water at 20°C. The recyclability of the bottles and cups 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 flakes became colorless and transparent.
B: A colored protective layer remained on the flakes.

<<Gas barrier property evaluation>>
The oxygen transmission rate of the bottles obtained in the above examples and comparative examples was measured to evaluate the gas barrier properties of the bottles. The oxygen transmission rate was measured in accordance with JIS K 7126-2:2006 using an oxygen gas transmission rate measuring device (manufactured by MOCON, product name: OX-TRAN2/20) under conditions of 23°C and 40% RH. The oxygen transmission rate was measured over the entire bottle with the mouth closed with a jig, and the value was divided by the surface area of the entire bottle excluding the mouth. The measurement results are shown in Table 1.

As is clear from Table 1, the container of the present invention has excellent recyclability.
Furthermore, the container of the present invention has gas barrier properties equivalent to those of a container having a barrier layer made only of PVA.

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

Claims (6)

A container comprising a support, a protective layer provided on at least one surface side of the support, and a barrier layer provided between the support and the protective layer,
The support comprises a thermoplastic resin,
the protective layer contains one or more selected from the group consisting of polyvinyl chloride, polystyrene, polyacetal, polyester, polyurethane, and polyvinyl acetal;
the barrier layer contains a carboxyl group-containing resin and a polyvinyl alcohol-based resin,
The container , wherein the carboxyl group-containing resin is polyacrylic acid . The container according to claim 1 , wherein the content of the carboxyl group-containing resin is from 1% by mass to 80% by mass with respect to all components contained in the barrier layer. The container according to claim 1 or 2 , wherein a mass ratio of the carboxyl group-containing resin to the polyvinyl alcohol-based resin is 1/20 or more and 10/1 or less. The container according to any one of claims 1 to 3 , wherein the barrier layer has a thickness of 0.1 µm or more and 200 µm or less. The container according to any one of claims 1 to 4 , wherein the thermoplastic resin is at least one selected from the group consisting of polyesters and polyolefins. A preform for a container according to any one of claims 1 to 5 .