JP7571766B2 - Press-through package packaging, lid material for press-through package, and heat seal agent for press-through package - Google Patents

Description

The present invention relates to a press-through package (PTP: Press Through Package) that can be used for medical, food, daily necessities, etc., a lid material for the press-through package, and a heat sealant for the press-through package.

A PTP package, which has a base and a lid, is known as one of the packaging formats for medicines, food, etc. A PTP package is made by attaching (heat sealing) the lid to a container that holds the contents using heat and pressure, and various types of heat sealing agents are used.

The lid material of PTP packages consists of a metal foil such as aluminum foil (also called aluminium foil), a plastic film, a deposition film, a base material such as paper or nonwoven fabric, a heat seal layer and a coating layer. For example, aluminium foil and plastic film are the mainstream for packaging pharmaceuticals.

Meanwhile, various materials are selected for PTP packaging containers depending on the application of the packaging material, but for example, polyvinyl chloride is the mainstream for pharmaceutical packaging. In recent years, with the movement towards dechlorination due to the problem of dioxin generation when polyvinyl chloride is burned, the use of non-oriented polypropylene (CPP) and amorphous polyethylene terephthalate (A-PET) has been increasing.

As such, various materials are used for PTP packaging, so a heat sealant that is appropriate for each packaging material and application is selected. In particular, when packaging pharmaceuticals, it is necessary to prevent the contents from deteriorating for a long period of time, so selecting the most suitable heat sealant is important.

For example, Patent Document 1 shows that a heat seal coating used in food packaging bags or blister packaging of pharmaceuticals that contains a polyester having a specific glass transition temperature and softening point, an anti-tack additive, and an organic solvent is suitable for PET film and BOPP film. Patent Document 2 shows that a heat seal agent containing a polyester resin, a chlorinated polypropylene resin, and an organic solvent has excellent heat sealability between aluminum foil and a polypropylene sheet.

Special table 2017-512724 publication Japanese Patent Publication No. 55-92778

Although various heat seal agents are provided according to the application, from the viewpoint of workability, it is preferable that one type of heat seal agent can be applied to various substrates. In particular, in recent years, container materials have been reconsidered from the viewpoint of environmental impact and have become more diverse, so there is a great demand for heat seal agents that have excellent heat sealability for all materials. Also, from the viewpoint of reducing environmental impact, it is preferable that the heat seal agent is water-based rather than solvent-based.

The present invention has been made to solve at least some of these problems, and aims to provide a press-through package packaging body, a lid material for press-through packages, and a heat sealant for press-through packages that have excellent heat sealing properties for various containers.

The present invention is a press-through package comprising a base material, a lid material having a heat seal layer provided on the base material, and a container covered with the heat seal layer, the heat seal layer being a coating layer of an aqueous heat seal agent containing an ethylene-vinyl acetate copolymer resin and an aqueous medium, and the container being formed of a resin containing at least one of the group consisting of polyester-based resins, polyolefin-based resins, fluorine-based resins, polyvinyl chloride, and polyvinylidene chloride.

The present invention also relates to a lid material for press-through packaging, which has a substrate and a heat seal layer provided on the substrate, the heat seal layer being a coating layer of an aqueous heat seal agent containing an ethylene-vinyl acetate copolymer resin and an aqueous medium, and the container is formed of a resin containing at least one member of the group consisting of polyester-based resins, polyolefin-based resins, fluorine-based resins, polyvinyl chloride, and polyvinylidene chloride.

The present invention also relates to a heat seal agent for press-through packaging that is applied onto a substrate to form a heat seal layer for bonding the substrate to a container, the heat seal agent being an ethylene-vinyl acetate copolymer resin and an aqueous medium, and the container being formed from a resin containing at least one member of the group consisting of polyester-based resins, polyolefin-based resins, fluorine-based resins, polyvinyl chloride, and polyvinylidene chloride.

The present invention provides a press-through package, a lid material for press-through packages, and a heat sealant for press-through packages that have excellent heat sealability for various containers and have a low environmental impact.

The press-through package of the present invention has a base material, a lid material having a heat seal layer provided on the base material, and a container covered by the heat seal layer. Each configuration of the package of the present invention will be described below. Note that the present invention is not limited to the following embodiments.

<Heat seal layer>
The heat seal layer of the present invention is provided by applying an aqueous heat sealant containing an ethylene-vinyl acetate copolymer resin and an aqueous medium to a substrate.

The ethylene-vinyl acetate copolymer resin is a copolymer in which ethylene and vinyl acetate are copolymerized, and in some cases, the ester portion may be partially or completely hydrolyzed. In addition, the ethylene-vinyl acetate copolymer resin may further be copolymerized with other monomers, but the content of structural units derived from other monomers is preferably 30% by mass or less of the entire copolymer, more preferably 10% by mass or less, even more preferably 3% by mass or less, and even more preferably 1% by mass or less.

The proportion of ethylene in the ethylene-vinyl acetate copolymer is not particularly limited, but from the viewpoint of heat seal strength, the proportion of ethylene in the copolymer is preferably 5% by mass or more, more preferably 10% by mass or more. On the other hand, from the viewpoint of blocking resistance, the proportion of ethylene in the copolymer is preferably 50% by mass or less, preferably 40% by mass or less, more preferably 30% by mass or less.

The weight average molecular weight of the ethylene-vinyl acetate copolymer resin is not particularly limited, but from the viewpoint of blocking resistance, it is preferable that it is 200,000 or more. On the other hand, from the viewpoint of adhesion and low-temperature heat sealability, the weight average molecular weight is preferably 1,000,000 or less.

The glass transition temperature of the ethylene-vinyl acetate copolymer is preferably 30°C or lower, more preferably 20°C or lower, and even more preferably 10°C or lower, since this improves the heat sealability at low temperatures. On the other hand, the lower limit of the glass transition temperature is preferably -40°C or higher, more preferably -30°C or higher, and even more preferably -20°C or higher.

The ethylene-vinyl acetate copolymer resin (A) used in the present invention may be a known one, and a commercially available product may be used. Examples of commercially available products include Sumikaflex (registered trademark) and Sumielite (registered trademark) manufactured by Sumika Chemtex Co., Ltd., and Aquatex EC1200, EC1700, EC1800, and EC3700 manufactured by Japan Coating Resins Co., Ltd.

The aqueous heat-sealing agent of the present invention contains the above-mentioned ethylene-vinyl acetate copolymer and an aqueous medium. In the aqueous heat-sealing agent, it is preferable that the ethylene-vinyl acetate copolymer resin (A) has a solids concentration adjusted to 20 to 70% by weight.

As the aqueous medium, water, water-soluble organic solvents that dissolve in water, etc. can be used. As the water, pure water such as ion-exchanged water, ultrafiltered water, reverse osmosis water, distilled water, etc., or ultrapure water can be used. From the viewpoint of long-term storage, it is preferable to use water that has been sterilized by ultraviolet irradiation or addition of hydrogen peroxide, etc., in order to prevent the growth of mold or bacteria.

Examples of water-soluble organic solvents include glycols such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, polyethylene glycol, and polypropylene glycol; diols such as butanediol, pentanediol, and hexanediol; glycol esters such as propylene glycol laurate; diethylene glycol ethers such as diethylene glycol monoethyl, diethylene glycol monobutyl, diethylene glycol monohexyl, and carbitol; glycol ethers such as propylene glycol ether, dipropylene glycol ether, and cellosolve including triethylene glycol ether; alcohols such as methanol, ethanol, isopropyl alcohol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, butyl alcohol, and pentyl alcohol; lactones such as sulfolane, esters, ketones, and γ-butyrolactone; lactams such as N-(2-hydroxyethyl)pyrrolidone; and various other solvents known as aqueous organic solvents, such as glycerin and its polyalkylene oxide adducts. These aqueous organic solvents can be used alone or in combination of two or more. It is preferable to use water, but if the wettability of the substrate is insufficient with water alone, it is preferable to use water in combination with an alcohol. As the alcohol, ethanol and isopropanol are preferable.

The heat sealant of the present invention may contain additives in addition to the ethylene-vinyl acetate copolymer and the aqueous medium. Examples of additives include wax, filler, defoamer, viscosity modifier, leveling agent, emulsifier, dispersion stabilizer, surfactant, tackifier, preservative, antibacterial agent, rust inhibitor, antioxidant, crosslinking agent, curing agent, curing catalyst, light stabilizer, ultraviolet absorber, photocatalytic compound, dye, inorganic pigment, organic pigment, extender pigment, plasticizer, antistatic agent, etc.

However, in order to improve the heat sealability and moist heat resistance over a long period of time, it is preferable that the heat sealant does not contain any additives. It is also preferable that the heat sealant does not substantially contain any other resins than the ethylene-vinyl acetate copolymer, and that the resin component contained in the heat sealant consists of the ethylene-vinyl acetate copolymer. In other words, the heat sealant of the present invention preferably has a simple composition consisting of an ethylene-vinyl acetate copolymer and an aqueous medium, and the heat sealant consisting of an ethylene-vinyl acetate copolymer and an aqueous medium can achieve adhesion to various substrates, heat sealability, and moist heat resistance.

The term "substantially free" means that no resin other than the ethylene-vinyl acetate copolymer is intentionally contained.
<Substrate>
The base material used as the lid material of the press-through package is not particularly limited, and known films, papers, metal foils, etc. that are usually used for packaging materials are preferably used. In the case of packaging medicines, it is preferable to use metal foils such as aluminum foil or films.

Examples of metal foil include aluminum foil.

Films include those made from raw materials such as PET (polyethylene terephthalate), A-PET (amorphous polyethylene terephthalate), PBT (polybutylene terephthalate), BOPP (biaxially oriented polypropylene), PE (polyethylene), PVC (polyvinyl chloride), PS (polystyrene), Ny (nylon), and EVOH (ethylene-vinyl alcohol copolymer). These films may have a metal deposition layer such as aluminum, or a metal oxide deposition layer such as silica or alumina, or a binary deposition of these. When the base film of the lid material and the container are made of the same material, recyclability can be improved by making them mono-material.

Examples of paper include those made by using natural fibers for papermaking such as wood pulp on a known papermaking machine. Papermaking conditions are not particularly specified. Examples of natural fibers for papermaking include wood pulp such as softwood pulp and hardwood pulp, non-wood pulp such as Manila hemp pulp, sisal hemp pulp, and flax pulp, and pulps obtained by chemically modifying these pulps. Types of pulp that can be used include chemical pulp made by sulfate cooking, acidic/neutral/alkaline sulfite cooking, soda cooking, etc., ground pulp, chemi-ground pulp, thermomechanical pulp, etc.

More specifically, examples of such materials include uncoated papers such as various printing papers, gravure paper, kraft paper, Kent paper, copy paper, wood-burning paper, and newspaper; lightly coated papers; coated papers such as art paper, one-sided art paper, coated paper, one-sided coated paper, and light-weight coated paper; fine paper; heavy-duty, general-purpose, and special-purpose unglazed kraft paper; unbleached wrapping papers such as veined kraft paper and one-sided glossy kraft paper; pure white roll paper; bleached kraft papers such as both-sided bleached kraft paper and one-sided glossy bleached kraft paper; other bleached wrapping papers; resin-impregnated papers such as paraffin paper, cardboard and paperboard, vapor-deposited papers in which metals such as aluminum are vapor-deposited onto these papers, and laminated papers in which these papers are laminated with metal foils such as aluminum foil.

A printing layer may be provided on these substrates. The printing layer is formed by a general printing method that has been used for printing on polymer films in the past, using various printing inks such as gravure ink, flexographic ink, offset ink, stencil ink, and inkjet ink. The printing layer may be provided on the surface of the substrate on the side of the heat seal layer, or on the other surface.

It is also preferable that the substrate has an overcoat layer on the surface opposite to the surface on which the heat seal layer is provided, i.e., on the outer surface that is not attached to the container. The overcoat layer is provided by applying an overcoating agent to the substrate. When heat-sealing the package, heat of nearly 300°C is applied, which can easily cause problems such as bleeding of the printed layer or, for example, cracking of the metal layer when metal foil is used as the substrate. However, by providing a coating agent, functionality such as heat resistance and abrasion resistance can be improved.

Any known coating agent can be used, but those containing polyvinyl butyral resin are preferred. Coating agents containing polyvinyl butyral resin have excellent adhesion, heat resistance, and abrasion resistance, and also have a high function of protecting the metal foil or metal layer.

The weight-average molecular weight of the polyvinyl butyral resin used in the coating agent is preferably 5,000 to 150,000, more preferably 6,000 to 100,000, and even more preferably 7,000 to 50,000. By setting the weight-average molecular weight of the polyvinyl butyral resin within the above range, it is possible to obtain a coating agent that has an excellent balance between the fluidity and dispersibility of the coating composition and the strength of the coating film.

The glass transition temperature (hereinafter sometimes referred to as Tg) of the polyvinyl butyral resin is preferably in the range of 50°C to 120°C, more preferably in the range of 55°C to 115°C, and even more preferably in the range of 60°C to 90°C. In the present invention, the glass transition temperature is obtained by measurement using a differential scanning calorimeter.

The hydroxyl value of the polyvinyl butyral resin is preferably in the range of 10 to 50 mol/% and more preferably 30 to 40 mol/%. By setting the hydroxyl value of the polyvinyl butyral resin in the above range, it has excellent curing properties when reacted with a crosslinking agent, and can achieve both strength and appropriate flexibility of the coating film.

The polyvinyl butyral resin content (solid content of polyvinyl butyral resin) is preferably 10 to 50 mass% relative to 100 mass% of the coating agent, more preferably 15 to 40 mass%, and most preferably 20 to 30 mass%.

The coating agent may contain one type of polyvinyl butyral resin or two or more types of polyvinyl butyral resins.

The coating agent preferably contains a polyisocyanate compound together with the polyvinyl butyral resin. By containing polyvinyl butyral and a polyisocyanate compound, a crosslinked resin can be formed by the curing reaction between them. This allows for improved adhesion, abrasion resistance, and heat resistance.

The polyisocyanate is not particularly limited as long as it is an isocyanate compound having a plurality of isocyanate groups that can react with polyvinyl butyral. Examples include polyisocyanates such as tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, 1,6-hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-methylenebis(cyclohexylisocyanate), lysine diisocyanate, trimethylhexamethylene diisocyanate, 1,3-(isocyanatomethyl)cyclohexane, 1,5-naphthalene diisocyanate, and triphenylmethane triisocyanate; and derivatives (modified products) of polyisocyanates such as adducts of these polyisocyanates, biuret products of these polyisocyanates, and isocyanurates of these polyisocyanates.

The polyisocyanate compound acts as a curing agent and can be appropriately selected for use, and may be aromatic or aliphatic. Examples of polyisocyanate compounds preferably used in the present invention include polyisocyanates such as hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), xylylene diisocyanate (XDI), tolylene diisocyanate (TDI), and diphenylmethane diisocyanate (MDI).

Among these, xylylene diisocyanate (XDI) and tolylene diisocyanate (TDI) are preferred.

[Isocyanate group content (equivalent)]
The isocyanate group content (equivalent) of the polyisocyanate relative to the hydroxyl value of the polyvinyl butyral resin is preferably in the range of 0.1 to 5.0, more preferably in the range of 0.2 to 4.0, and even more preferably in the range of 0.3 to 3.0. By setting it in this range, it is possible to achieve both adhesion to the metal foil or metal layer and abrasion resistance. The isocyanate group content (equivalent) of the polyisocyanate relative to the hydroxyl value of the polyvinyl butyral resin was calculated by the following method.

Hydroxyl value of polyvinyl butyral resin: A (mgKOH/g)
Mass of polyvinyl butyral resin: B (g)
NCO% of polyisocyanate: C (%)
Mass of polyisocyanate: D (g)

NCO/OH ratio=C×D×561/(A×B×42)
D (g) = ((A x B) / C) x (42/561) x NCO/OH (equivalent ratio)
The coating agent may contain a general-purpose resin in addition to the polyvinyl butyral resin and polyisocyanate. For example, epoxy resin, cellulose resin, polyamide resin, vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-acrylic copolymer resin, rosin resin, ethylene-vinyl acetate copolymer resin, vinyl acetate resin, acrylic resin, styrene resin, dammar resin, styrene-maleic acid copolymer resin, polyester resin, alkyd resin, terpene resin, phenol-modified terpene resin, ketone resin, cyclized rubber, chlorinated rubber, polyacetal resin, petroleum resin, and modified resins thereof. These resins may be used alone or in combination of two or more. In the case of pharmaceutical or food applications, it is preferable not to use epoxy resin or chlorine-based resin from the viewpoint of safety and hygiene.

In addition, to improve abrasion resistance, anti-friction agents, slip agents, etc. may be added. Fatty acid amides, silicone, polyethylene, polypropylene, PTFE, etc. can be used alone or in combination of two or more.

A catalyst may be added to improve the curing property. Examples of the catalyst include organic tin compounds, tertiary amine compounds, organic titanium compounds, and organic zirconium compounds.

If necessary, it is preferable to use organic compound-based antiblocking agents other than those mentioned above, such as fatty acid amides, fatty acid esters, and higher fatty acids. These organic compound-based antiblocking agents prevent blocking by bleeding out onto the surface of the heat seal layer. For this reason, particle-based antiblocking agents and organic compound-based antiblocking agents may be used in combination. If a large amount of organic compound-based antiblocking agents are added, they can impair adhesion and easily cause poor adhesion, so it is preferable to limit the amount added to a small amount.

When actually applying the coating agent to a substrate, it is preferable to dissolve it in various organic solvents to a solid content of 20% by mass in order to improve application performance.

There are no particular limitations on the dilution solvents that can be used, but examples include various organic solvents such as aromatic hydrocarbons such as toluene, xylene, Solvesso #100, Solvesso #150, etc., aliphatic hydrocarbons such as hexane, heptane, octane, decane, etc., and esters such as methyl acetate, ethyl acetate, isopropyl acetate, butyl acetate, amyl acetate, ethyl formate, butyl propionate, etc. Examples of water-miscible organic solvents include alcohols such as methanol, ethanol, propanol, and butanol; ketones such as acetone, methyl ethyl ketone, and cyclohexanone; and glycol ethers such as ethylene glycol (mono, di) methyl ether, ethylene glycol (mono, di) ethyl ether, ethylene glycol monopropyl ether, ethylene glycol monoisopropyl ether, monobutyl ether, diethylene glycol (mono, di) methyl ether, diethylene glycol (mono, di) ethyl ether, diethylene glycol monoisopropyl ether, diethylene glycol monobutyl ether, triethylene glycol (mono, di) methyl ether, propylene glycol (mono, di) methyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, and dipropylene glycol (mono, di) methyl ether. Among these, it is preferable to use alcohols, ketones such as methyl ethyl ketone, and mixtures thereof. In recent years, from the viewpoint of the working environment, it is more preferable not to use aromatic solvents such as toluene and xylene, or ketone solvents.

The coating method for the substrate can be, for example, by using a bar coater, gravure coating, roll coating, knife coating, kiss coating, etc. In order to maximize the effects of the present invention, the coating amount for the metal foil or metal layer is preferably 0.5 to 5 g/ ^m2 , and the drying conditions are preferably in the range of 120 to 200°C for 5 to 100 seconds.

[Cover material]
The lid material of the present invention is obtained by applying a heat sealant to a substrate and drying it. A heat seal layer (a dried coating of the heat sealant of the present invention) may be provided directly on the substrate, or one or more primer layers may be provided on the substrate. When a primer layer is provided, the primer used to form the primer layer is not particularly limited, and a known primer may be used.

A known method can be used to apply the heat sealant. For example, a roll coater, gravure coater, flexo coater, air doctor coater, blade coater, air knife coater, squeeze coater, impregnation coater, transfer roll coater, kiss coater, curtain coater, cast coater, spray coater, die coater, offset printing machine, screen printing machine, etc. can be used. After coating, a drying process can be performed in an oven, etc.

As a drying method, conventionally known means such as hot air, electric heat, infrared rays, and electron beams can be used. The heating temperature is preferably 50 to 250°C, and the heating time is preferably 0.1 to 30 seconds.

The amount of the heat sealant applied is adjusted appropriately depending on the desired seal strength and the substrate, and is, for example, 1.0 g/m ² to 5.0 g/m ² .

[container]
The container of the press-through package has a pocket-shaped recess for accommodating the contents, and a flange provided at the end of the container is bonded to the lid material via a heat seal layer, so that the contents can be accommodated in a sealed state. A heat seal layer may be provided on the flange of the container.

The container is made of a transparent thermoplastic resin sheet formed from at least one resin selected from the group consisting of polyester resin, polyolefin resin, fluorine resin, polyvinyl chloride, and polyvinylidene chloride. It may also be a laminated sheet made by laminating two or more of these thermoplastic resin sheets.

In addition, a sheet laminated or coated with a resin containing at least one of the group consisting of polyester resin, polyolefin resin, fluorine resin, polyvinyl chloride, and polyvinylidene chloride may be used on a known PTP container or thermoplastic resin sheet. The layer in direct contact with the heat seal layer may be formed of a resin containing at least one of the group consisting of polyester resin, polyolefin resin, fluorine resin, polyvinyl chloride, and polyvinylidene chloride.

Examples of polyester resins include polyethylene terephthalate, polyethylene naphthalate, polyethylene isophthalate, polybutylene terephthalate, etc.

Examples of polyolefin resins include polyethylene resins, polypropylene resins, ethylene-vinyl alcohol copolymer resins, and resins made of cyclic olefins. Containers using polyolefin resins are preferred because they have excellent heat sealability with the heat sealing agent of the present invention, and resins containing polypropylene are particularly preferred.

Fluorine-based resins include polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether (EPA), tetrafluoroethylene-ethylene copolymer (ETFE), polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), chlorotrifluoroethylene-ethylene copolymer (ECTFE), etc.

Among them, polyethylene terephthalate, polypropylene, polyethylene, polyvinyl chloride, polyvinylidene chloride, and polychlorotrifluoroethylene (PCTFE) are preferred. Polychlorotrifluoroethylene (PCTFE) has excellent water vapor barrier properties and oxygen barrier properties, so that the container can be made thinner and lighter, providing a more sustainable package. Materials containing fluorine, such as PCTFE, generally have poor heat sealability, but by using the heat seal agent of the present invention, a container having excellent heat sealability can be realized even when a fluorine-based material is used.
These sheets can be molded into a desired shape by vacuum heating, pressure forming, or the like to obtain containers for press-through packages.

[Press-through package packaging]
The press-through package of the present invention is used by bonding the above-mentioned lid material and container with a heat seal layer. That is, the press-through package can be produced by a method in which a content such as a medicine is placed in a recess of the container, and the lid material is placed on the container with the heat seal layer facing the container and thermally bonded.

The press-through package of the present invention can be used as a packaging material for medicines, tablets, and foods such as candy and chocolate. It can also be used as a packaging material for blister packs of toothbrushes, dry batteries, toys, etc.

The present invention will be explained in more detail with reference to examples. In the following, "parts" and "%" are all based on mass.

In the present invention, the number average molecular weight and weight average molecular weight (converted into polystyrene) were measured by GPC using an HLC8220 system manufactured by Tosoh Corporation under the following conditions.
Separation column: Four TSKgel GMHHR-N columns manufactured by Tosoh Corporation were used. Column temperature: 40
° C. Mobile phase: tetrahydrofuran manufactured by Wako Pure Chemical Industries, Ltd. Flow rate: 1.0 ml/min. Sample concentration: 1.0 wt %. Sample injection amount: 100 microliters. Detector: differential refractometer.

The glass transition temperature (Tg) was measured in a differential atmosphere using a cooling device in the temperature range of -8
The DMA method was used under conditions of 0 to 450° C. and a temperature increase rate of 10° C./min.

[Preparation of heat sealant]
(Heat sealant 1)
A commercially available water dispersion of ethylene-vinyl acetate copolymer resin (solid content 50%) and water were adjusted to a mass ratio of ethylene-vinyl acetate copolymer resin dispersion/water = 80/20 to prepare heat sealing material 1 (HS1).

(Heat sealant 2)
A vinyl chloride-vinyl acetate copolymer resin (weight average molecular weight 50,000, vinyl chloride ratio 85%, glass transition point (Tg) 75°C, K value measured by ISO1628-2 45) was dissolved in a mixed solvent of methyl ethyl ketone and ethyl acetate to a solid content of 25%, to prepare heat sealing agent 2 (HS2). The mass ratio of methyl ethyl ketone and ethyl acetate in the mixed solvent was methyl ethyl ketone/ethyl acetate = 50/50.

(Heat sealant 3)
Vinyl chloride-vinyl acetate copolymer resin (weight average molecular weight 50,000, vinyl chloride ratio 85%, glass transition point (Tg) 75°C, K value measured by ISO1628-2 45) and polyester resin (number average molecular weight 30,000, glass transition point (Tg) -20°C) were dissolved in a mixed solvent of methyl ethyl ketone and ethyl acetate to a solid content of 16%, to prepare heat sealing agent 3 (HS3). The ratio of the chloride-vinyl acetate copolymer resin to the polyester resin was 1:1 by mass. The ratio of methyl ethyl ketone to ethyl acetate in the mixed solvent was methyl ethyl ketone/ethyl acetate = 60/40 by mass.

[Preparation of lid material]
Example 1
Heat sealant 1 (HS1) was applied to a hard aluminum foil (manufactured by Toyo Aluminum Co., Ltd.) using a bar coater (application amount 4 g/ ^m2 ), and after coating, it was dried at 180°C/10 seconds to form a heat seal layer, thereby producing lid material 1.

(Comparative Examples 1 and 2)
Heat seal agents 2 and 3 (HS2 and HS3) were applied to hard aluminum foil similar to that in Example 1 using a bar coater (application amount 4 g/ ^m2 ), and after coating, the coating was dried at 180°C/10 seconds to form a heat seal layer, thereby producing lid materials 2 and 3.

The following evaluations were carried out on the lid materials 1 to 3 that were created.

[Evaluation Criteria 1: Adhesion to Substrate]
The prepared lid material is placed on a flat table with the heat seal layer facing up, 24 mm wide cellophane tape from Nichiban is attached to the surface with the heat seal layer, and the cellophane tape is rubbed from above with a cloth or the like so that the cellophane tape is completely adhered to the coating film. While a frame about 2 mm larger than the attached cellophane tape is pressed firmly against the coating film on the outside of the cellophane tape, the cellophane tape attached to the coating film is forcefully peeled upward, and the degree of adhesion of the coating film to the aluminum foil is visually judged.

(Evaluation Criteria)
5: No peeling of the coating film was observed in the cellophane tape-attached area.
4: Less than 10% of the coating film in the cellophane tape-attached area peeled off. 3: 10% or more but less than 30% of the coating film in the cellophane tape-attached area peeled off. 2: 30% or more but less than 50% of the coating film in the cellophane tape-attached area peeled off.
1: Simple: 50% or more of the coating film at the cellophane tape-attached portion was peeled off.

[Evaluation Criteria 2: Blocking Property]
The coated surface of the heat seal agent of the prepared lid material and the uncoated glossy hard aluminum surface were overlapped for 24 hours in an atmosphere of 40°C under a pressure of 0.5 MPa (5.0 kgf/ ^cm2 ), and then the state of blocking when peeled off was evaluated by the feel when peeled off by hand. Each test was performed three times and evaluated.

A: No blocking at all.
△: Some blocking.
×: Strong blocking.
The results are shown in Table 1.

Next, test pieces were made using lid materials 1 to 3 as follows:

(Examples 2 to 5, 8)
The covering material 1 was laminated with various sheets shown in the table via a heat seal layer. Using a heat seal tester having a heat seal part for embossing, each was heat sealed at 100°C, 140°C, and 180°C (0.3 MPa for 1 second) to prepare test pieces.

Example 6
Polyvinyl butyral resin (weight average molecular weight 15,000, hydroxyl value approximately 35 mol/%, glass transition point 70°C) was dissolved in a mixed solvent of methyl ethyl ketone and isopropyl alcohol in a mass ratio of 45:55 to a solid content of 25% to prepare a polyvinyl butyral solution.

Next, 100 parts of the polyvinyl butyral solution was mixed and stirred with 12 parts of Takenate D-110NB (xylylene diisocyanate (XDI)) as a polyisocyanate so that the NCO group content (equivalent) of the isocyanate was 0.5 to 2.5 relative to the hydroxyl value of the polyvinyl butyral resin, to prepare an overcoating agent.

The prepared overcoating agent was applied to the opposite side of the heat seal layer of the lid material 1 using a gravure coater so that the coating amount after baking onto the hard aluminum foil would be 2 g/ ^m2 , and then dried at 180°C for 10 seconds to obtain the lid material 4.
A test piece of Example 6 was prepared in the same manner as in Examples 2 to 5 using the lid material 4.

(Example 7)
A commercially available industrial nitrocellulose (solid content 70%), a commercially available acrylic resin (solid content 50%), a commercially available melamine resin (solid content 98%), a mixed solvent, and an acid catalyst as an additive were mixed in a mass ratio of 15:11:4:69:1 to prepare an overcoating agent with a solid content of 20%. The mixed solvent used was a mixture of methyl ethyl ketone, ethyl acetate, and isopropyl alcohol in a mass ratio of 50:30:20.

The prepared overcoating agent was applied to the opposite side of the heat seal layer of the lid material 1 using a gravure coater so that the coating amount after baking onto the hard aluminum foil would be 2 g/ ^m2 , and then dried at 180°C for 10 seconds to obtain the lid material 5.
A test piece of Example 7 was prepared in the same manner as in Examples 2 to 6 using the lid material 5.

(Comparative Examples 2 to 9)
Test pieces were prepared in the same manner as in Examples 2 to 6 by using each of Lid Material 2 and Lid Material 3 and overlapping it with the various films shown in the table via a heat seal layer.
The test pieces thus prepared were subjected to the following evaluations.

[Evaluation Criteria 3: Heat Sealability]
For each test piece heat-sealed at 100° C., 140° C., and 180° C., the adhesive strength was measured at a peel speed of 100 mm/min, a peel direction of 180°, and a peel width of 15 mm using a small tabletop tester EZ test manufactured by Shimadzu Corporation. The evaluation criteria were 5-level evaluation as follows.

5: 9 (N/15mm) or more 4: 6 (N/15mm) or more but less than 9 (N/15mm) 3: 3 (N/15mm) or more but less than 6 (N/15mm) 2: Less than 3 (N/15mm) 1: No adhesion at all

[Evaluation Criteria 4: Moist Heat Resistance]
Each test piece heat-sealed at 180°C was left in a thermostatic chamber under a 40°C/75% humidity environment, and the heat sealability after 3 months was measured using a small tabletop tester EZ test manufactured by Shimadzu Corporation, at a peel speed of 100 mm/min, a peel direction of 180°, and a peel width of 15 mm. The evaluation criteria were as follows:

5: 90% or more of the initial adhesive strength is retained. 4: 70% or more but less than 90% of the initial adhesive strength is retained. 3: 50% or more but less than 70% of the initial adhesive strength is retained. 2: 30% or more but less than 50% of the initial adhesive strength is retained. 1: Less than 30% of the initial adhesive strength is retained. The results are shown in Tables 2 to 4.

"PET" in the table means polyethylene terephthalate sheet (film thickness 250 μm).
"CPP" is a non-oriented polypropylene sheet (film thickness 250 μm)
"PVC" is a hard polyvinyl chloride sheet (film thickness 250 μm),
"PVDC" is a sheet (film thickness 225 μm) made by coating a hard polyvinyl chloride sheet with polyvinylidene fluoride (PVDC).
"PCTFE" is a composite sheet of polychlorotrifluoroethylene (film thickness 350 μm) (heat seal surface is PCTFE side)
Represents.
In addition, "-" in the table means that no evaluation was performed.

The table shows that the packaging of the present invention has excellent heat sealability for various containers. In addition, since it can exhibit excellent heat sealability even at a relatively low temperature of 100°C, it is possible to reduce the damage that the packaging and contents suffer when exposed to high temperatures during heat sealing.

As shown in Examples 6 and 7, it was also confirmed that the composition with an overcoat layer had excellent properties. In particular, the overcoat layer of Example 6 showed no discoloration or blistering on the coating surface even after heat sealing, demonstrating excellent heat resistance.

Claims (10)

Substrate and
A heat seal layer is provided on the substrate,
the heat seal layer is a coating layer of an aqueous heat seal agent containing an ethylene-vinyl acetate copolymer resin and an aqueous medium;
the heat seal layer has a heat sealability with respect to any container formed of a resin containing at least one member of the group consisting of a polyester resin, a polyolefin resin, a fluorine resin, polyvinyl chloride, and polyvinylidene chloride;
The lid material for press-through packages is used as a press-through package package in which the lid material for press-through packages and the container are bonded via the heat seal layer . The lid material for press-through packages according to claim 1, wherein the substrate is a metal foil or a sheet having a metal layer. The press-through package lid material according to claim 2, wherein the metal foil is an aluminum foil. 3. The lid material for press-through packages according to claim 1, wherein the heat seal layer is substantially free of any resin other than an ethylene-vinyl acetate copolymer resin. 3. The lid material for press-through packaging according to claim 1, further comprising an overcoat layer on the surface of the substrate opposite to the surface on which the heat seal layer is provided. 6. The lid material for press-through packages according to claim 5, wherein the overcoat layer is a coating layer of an overcoating agent, and the overcoating agent contains a polyvinyl butyral resin and a polyisocyanate compound. The proportion of ethylene in the ethylene-vinyl acetate copolymer resin is 5% by mass or more and 50% by mass or less,
the content of structural units derived from other monomers in the ethylene-vinyl acetate copolymer resin is 30% by mass or less of the entire copolymer,
The weight average molecular weight of the ethylene-vinyl acetate copolymer resin is 200,000 or more and 1,000,000 or less,
The press-through package lid material according to claim 1, wherein the ethylene-vinyl acetate copolymer resin has a glass transition temperature of -20°C or higher and 30°C or lower. The amount of the heat sealant applied is 1.0 g/m ² to 5.0 g/m ² ;
2. The lid material for press-through packages according to claim 1, wherein the heat seal strength when the heat seal layer and the container are heat sealed at 100° C. and 0.3 MPa for 1 second (measured using a small tabletop tester EZ test manufactured by Shimadzu Corporation at a peel speed of 100 mm/min, a peel direction of 180° peeling, and a peel width of 15 mm) is 3 N/15 mm or more. A press-through package using the lid material for press-through packages according to claim 1. A heat sealant for press-through packaging that is applied onto a substrate to form a heat seal layer for bonding the substrate and a container,
The heat sealant is an ethylene-vinyl acetate copolymer resin and an aqueous medium,
The container is made of polyester resin, polyolefin resin, fluorine resin, polyvinyl chloride resin ,
The resin is formed from at least one member selected from the group consisting of vinyl, polyvinylidene chloride, and polyvinylidene chloride .
A heat-sealing agent for press-through packaging, characterized in that the heat-sealing layer has heat-sealing properties with respect to any of the containers .