CN117382290A - Resealable heat seal laminate and resealable packaging container - Google Patents

Abstract

The present invention provides a resealable heat-seal laminate which, when a lid material is peeled off from a container, is less likely to remain in a heat-seal portion on the lid material side or to be pulled into a thread (string) shape to exhibit sufficient initial unsealing strength, and which, even after unsealing, can be resealed with practically sufficient strength by pressing the lid material and the container, and which, further, is free from bleeding of liquid components on the laminate surface with the lapse of time, and is free from a decrease in the unsealing strength, and a resealable packaging container. The above object is achieved by a resealable heat-seal laminate comprising a base material (A), an adhesive layer (B) and a heat-seal resin layer (C) arranged in this order, wherein the adhesive layer (B) contains an acrylic copolymer (D), and the heat-seal resin layer (C) contains a polyethylene resin and further contains at least one of a polypropylene resin and a polybutylene resin.

Description

Resealable heat seal laminate and resealable packaging container

Technical Field

The present invention relates to a resealable heat seal laminate. Further relates to a resealable packaging container having the resealable heat seal laminate.

Background

Conventionally, as packaging containers for ice foods such as cupped noodles, cupped soups, snack foods, chocolate, jelly and the like, plastic containers such as polyethylene containers, polypropylene containers and polystyrene containers, paper containers coated with polyethylene resins, and metal containers such as iron and aluminum have been used. As a lid material of these containers, a laminate using an adhesive resin layer (heat-seal resin layer) exhibiting adhesiveness by heat-sealing on a surface to be bonded to a container body is generally used. Examples of the structure of the laminate include a paper/polyethylene film/aluminum foil/polyethylene film/heat-seal resin layer, a polyethylene terephthalate (PET) film/aluminum foil/polyethylene film/heat-seal resin layer, and the like. In the lid material of the above configuration example, the heat-seal resin layer is bonded to the container body by heat sealing (heat fusion), and therefore cannot be bonded again to the container body once peeled off.

In the market, there are demanded a lid material and a packaging container having a property (hereinafter also referred to as resealability) that the lid material can be temporarily unsealed and a need for the purpose of saving the food left after eating again, and active researches have been made. A cover material is disclosed which can be resealed by using a multilayer film provided with a layer having resealability.

Specifically, patent document 1 discloses a cover material for a multilayer film composed of a base material, a hot-melt adhesive, and a hot-melt adhesive. There is proposed a cover material which is sealed by heat-sealing a paper container obtained by coating the cover material of the multilayer film with a polyethylene resin, and which can be resealed without breaking or stringing when the cover material is peeled off, with the hot-melt adhesive layer exposed.

Patent document 2 proposes a high-strength cap material having excellent productivity by coextrusion lamination of a base material in the order of an adhesive layer and a sealant layer composed of a styrene monomer, a styrene block copolymer, and a tackifier.

However, the cover materials described in patent documents 1 and 2 contain liquid components such as mineral oil and styrene monomer, and thus have problems in that bleeding out to the hot-melt adhesive layer and the sealant layer and a decrease in re-opening strength occur with the passage of time due to the storage environment.

Patent document 1: japanese patent application laid-open No. 2013-082914

Patent document 2: japanese patent application laid-open No. 2018-051926

Disclosure of Invention

Problems to be solved by the invention

The present invention has been made in view of the above-described problems, and an object thereof is to provide a resealable heat-seal laminate which, when a lid material is peeled from a container, is less likely to remain in a heat-seal portion of a heat-seal resin layer on the lid material side or is less likely to be pulled into a wire shape (drawn) to exhibit sufficient initial unsealing strength, and which, even after unsealing, can be resealed with practically sufficient strength by pressing the lid material and the container, and further, which does not cause bleeding of liquid components on the laminate surface with the lapse of time, and which is free from a decrease in the unsealing strength, and a resealable packaging container.

Means for solving the problems

As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by producing a resealable heat seal laminate as follows:

the resealable heat-sealed laminate is a laminate comprising a base material (A), an adhesive layer (B) and a heat-sealed resin layer (C) arranged in this order, wherein the adhesive layer (B) contains an acrylic copolymer (D),

the heat-sealing resin layer (C) contains a polyethylene-based resin and further contains at least one of a polypropylene-based resin and a polybutylene-based resin.

That is, the present invention relates to a resealable heat-seal laminate comprising a base material (A), an adhesive layer (B) and a heat-seal resin layer (C) arranged in this order,

the adhesive layer (B) contains an acrylic copolymer (D),

the heat-sealing resin layer (C) contains a polyethylene-based resin and further contains at least one of a polypropylene-based resin and a polybutylene-based resin.

The present invention relates to a resealable heat-sealed laminate in which the adhesive layer (B) further contains a curing agent (E).

The present invention relates to a resealable heat-sealed laminate wherein the adhesive layer (B) further contains a tackifier (F).

The present invention relates to a resealable heat-sealed laminate in which the tackifier (F) contains a rosin-based tackifier (F1) or a terpene-based tackifier (F2).

The present invention relates to a resealable packaging container having the resealable heat seal laminate and a container body as described above.

Effects of the invention

The laminate of the present invention can provide a resealable heat-seal laminate and a resealable packaging container, wherein a part of the heat-seal resin layer is less likely to remain in a heat-seal portion on the side of the lid material or less likely to be pulled into a thread (wire) when the lid material is peeled off from the container, thereby exhibiting sufficient initial unsealing strength, and the laminate can be resealed with practically sufficient strength by pressing the lid material and the container even after unsealing, and further, liquid components are not oozed from the laminate surface with the lapse of time, and the unsealing strength is not lowered.

Detailed Description

Before describing the present invention in detail, terms will be defined. Sheets, films and tapes are synonymous. (meth) acrylic acid includes acrylic acid and methacrylic acid. (meth) acrylates include acrylates and methacrylates. The monomer is a monomer containing an ethylenically unsaturated double bond.

In the present specification, a numerical range specified by "to" includes a range in which numerical values described before and after "to" are set as a lower limit value and an upper limit value.

The resealable heat-seal laminate of the present invention is formed by arranging a base material (A), an adhesive layer (B) and a heat-seal resin layer (C) in this order. The heat-sealing resin layer (C) can be bonded to the container body by exhibiting adhesiveness by heating. The laminate of the present invention can then be torn off from the container to be unsealed. At this time, the heat-bonded portion of the heat-seal resin layer (C) is designed so as to be transferred to the container side and peeled from the adhesive layer (B) between layers. Therefore, in the peeled laminate, the adhesive layer (B) is exposed (but only the portion heat-sealed with the container), and the heat-sealed resin layer (C) is transferred to the container. When the container is sealed again, the exposed adhesive layer (B) is brought into contact with the heat-sealing resin layer (C) transferred to the container, and the adhesive layer (B) and the heat-sealing resin layer (C) exhibit an appropriate adhesion between them. The laminate of the present invention has a resealability function by such a mechanism.

Substrate (A) >, substrate

The base material (a) of the present invention may be any material as long as it can support the adhesive layer (B) and the heat-sealing resin layer (C), and paper, plastic film, metal foil, or the like can be used. Examples of the plastic film include: polyester resin films such as polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate, fluorine films such as polyvinyl fluoride, polyvinylidene fluoride films, polytetrafluoroethylene films and ethylene-tetrafluoroethylene copolymer films, and cellulose films such as acrylic films and triacetyl cellulose films. Among them, from the viewpoints of film rigidity, water vapor barrier property, oxygen barrier property, and cost, a polyester resin film is preferable, and a polyethylene terephthalate (also referred to as "PET") film is more preferable. Examples of the metal foil include aluminum foil. These substrates may be used as a single layer or may be laminated with 2 or more layers using an adhesive or the like. The substrate may have a structure having an inorganic layer formed by vapor deposition or sputtering of a metal oxide or a non-metal inorganic oxide.

The thickness of the base material (a) is not particularly limited as long as it is in a range usable as a cover material, and is preferably 10 to 1000 μm.

< adhesive layer (B) >)

The adhesive layer (B) of the present invention can be formed by applying an adhesive containing the acrylic copolymer (D) to the substrate (a) and optionally drying a dissolution medium such as water or a solvent. The adhesive and the acrylic copolymer (D) may or may not contain water or a solvent as a dissolution medium.

Acrylic copolymer (D)

The acrylic copolymer (D) can be obtained by polymerizing monomers with a radical polymerization initiator by a conventional method. The polymerization method is not particularly limited, and when a solvent is used as a dissolution medium, solution polymerization is preferably used. When water is used as the dissolution medium, emulsion polymerization is preferably used in view of easiness in obtaining a resin dispersion having a high molecular weight, a low viscosity and a high solid content. Examples of the monomer include (meth) acrylate monomers, hydroxyl group-containing monomers, carboxyl group-containing monomers, amide group-containing monomers, amino group-containing monomers, epoxy group-containing monomers, aromatic ring-containing monomers, alicyclic hydrocarbon group-containing monomers, and vinyl esters.

Examples of the (meth) acrylic acid ester monomer include (meth) acrylic acid alkyl ester monomers having a linear or branched alkyl group such as methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, isobutyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, n-dodecyl (meth) acrylate, n-tridecyl (meth) acrylate, and n-tetradecyl (meth) acrylate. Among them, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate are preferable.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate.

Examples of the carboxyl group-containing monomer include maleic acid, fumaric acid, itaconic acid, citraconic acid, and alkyl or alkenyl monoesters thereof, acrylic acid, methacrylic acid, crotonic acid, and cinnamic acid.

Examples of the amide group-containing monomer include (meth) acrylamide, N-methyl (meth) acrylamide, N-dimethyl (meth) acrylamide, N-diethyl (meth) acrylamide, N' -methylenebisacrylamide, N-methylol (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, N-methoxyethyl (meth) acrylamide, N-vinylpyrrolidone, diacetone acrylamide, N-dimethylaminopropyl (meth) acrylamide, and (meth) acryloylmorpholine.

Examples of the amino group-containing monomer include N, N-dimethylaminoethyl (meth) acrylate and N, N-dimethylaminopropyl (meth) acrylate.

Examples of the epoxy group-containing monomer include glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, allyl glycidyl ether, and the like.

Examples of the aromatic ring-containing monomer include phenyl acrylate, phenoxyethyl (meth) acrylate, benzyl (meth) acrylate, biphenyl (meth) acrylate, styrene, vinyl toluene, and α -methylstyrene.

Examples of the alicyclic hydrocarbon group-containing monomer include cyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, and isobornyl (meth) acrylate.

Examples of vinyl esters include vinyl acetate, vinyl propionate, and vinyl laurate.

The monomer constituting the acrylic copolymer (D) may be one kind, or two or more kinds may be used in combination. Among them, at least any one of a monomer containing an alkyl (meth) acrylate monomer and further containing a hydroxyl group-containing monomer and a carboxyl group-containing monomer is preferable. When the alkyl (meth) acrylate monomer is contained, it is preferably contained in an amount of 30 to 99 parts by mass based on 100 parts by mass of the total mass of the monomer. When at least one of the hydroxyl group-containing monomer and the carboxyl group-containing monomer is contained, the total amount of these monomers is preferably 0.1 to 10 parts by mass based on 100 parts by mass of the total mass of the monomers.

As the radical polymerization initiator used in the polymerization reaction, known oil-soluble polymerization initiators and water-soluble polymerization initiators may be used, and one kind of them may be used alone or two or more kinds of them may be used in combination.

The oil-soluble polymerization initiator is not particularly limited, and examples thereof include: organic peroxides such as benzoyl peroxide, t-butyl peroxybenzoate, t-butyl hydroperoxide, t-butyl peroxy (2-ethylhexanoate), t-butyl peroxy-3, 5-trimethylhexanoate, di-t-butyl peroxide, dilauryl peroxide, etc.,

Azodicarbonitrile such as 2,2 '-azobisisobutyronitrile, 2' -azobis-2, 4-dimethylvaleronitrile, 2 '-azobis (4-methoxy-2, 4-dimethylvaleronitrile), and 1,1' -azobis-cyclohexane-1-carbonitrile.

The emulsion polymerization is preferably performed using a water-soluble polymerization initiator, and as the water-soluble polymerization initiator, for example, conventionally known initiators such as Ammonium Persulfate (APS), sodium persulfate (NPS), potassium persulfate (KPS), hydrogen peroxide, and 2,2' -azobis (2-methylpropionamidine) dihydrochloride can be preferably used.

[ reducing agent ]

In the emulsion polymerization, a reducing agent may be used in combination with the polymerization initiator. By using the reducing agent in combination, the acceleration of the emulsion polymerization rate and the emulsion polymerization at low temperature are facilitated. Examples of the reducing agent include: reducing organic compounds such as metal salts of ascorbic acid, isoascorbic acid, tartaric acid, citric acid, glucose, formaldehydesulfoxylate, rongalite, thiourea dioxide, etc., and reducing inorganic compounds such as sodium thiosulfate, sodium sulfite, sodium bisulfite, sodium metabisulfite, ferrous chloride, etc.

[ basic Compound ]

In the polymerization of the monomer, a basic compound may be used as a neutralizing agent in order to improve the stability of the acrylic copolymer (D). Examples of the basic compound include: ammonia water, various organic amines such as dimethylaminoethanol, diethanolamine and triethanolamine, and inorganic alkaline agents such as hydroxides of alkali metals such as sodium hydroxide, lithium hydroxide and potassium hydroxide; from the viewpoint of water resistance, ammonia is preferable.

The glass transition temperature (Tg) of the acrylic copolymer (D) is preferably-80 to-10 ℃, more preferably-75 to-20 ℃, and still more preferably-70 to-30 ℃. When the glass transition temperature is within this range, the adhesive strength of the adhesive can be improved. The glass transition temperature may be two or more, and preferably at least one or more in the above range.

The glass transition temperature in the present invention is a glass transition temperature measured by Differential Scanning Calorimetry (DSC) for a resin having 100 mass% of a nonvolatile component obtained after drying.

For example, the glass transition temperature is: sample-filled aluminum pans and unfilled aluminum pans, in which about 10mg of the samples were weighed, were placed in a DSC apparatus, quenched with liquid nitrogen in a nitrogen stream to-100℃and then warmed to 200℃at 20℃per minute, and the DSC curves were plotted. The following can be obtained: the extrapolated glass transition initiation temperature (Tig) is obtained from the intersection point of a straight line obtained by extending the base line of the DSC curve on the low temperature side (the DSC curve portion in the temperature region where transition to the test piece and reaction do not occur) toward the high temperature side and a tangent line drawn from the point where the curve slope of the stepwise change portion of the glass transition is maximum, and is taken as the glass transition temperature.

The weight average molecular weight (Mw) of the acrylic copolymer (D) is preferably 50,000 ～ 2,000,000, more preferably 100,000 ～ 1,500,000, and further preferably 300,000 ～ 1,000,000. By having the weight average molecular weight within this range, the adhesion of the adhesive becomes higher.

The weight average molecular weight is a polystyrene equivalent obtained by Gel Permeation Chromatography (GPC) of a resin. For example, the following measurement can be made: the temperature of the column (KF-805L, KF-803L and KF-802 manufactured by Showa electric Co., ltd.) was 40 ℃, THF (tetrahydrofuran) was used as an eluent, the flow rate was 0.2ml/min, the detection was RI, the sample concentration was 0.02 mass%, and polystyrene was used as a standard sample.

If the weight average molecular weight of the acrylic copolymer (D) is large, it may not be dissolved in THF as an eluent. In this case, the measurement cannot be performed, and therefore the weight average molecular weight is determined to be more than 2,000,000.

When a solvent is used for the adhesive or the acrylic copolymer (D), examples of the solvent include: alcohols such as methanol, ethanol, propanol, butanol, ethylene glycol methyl ether, and diethylene glycol methyl ether, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, ethers such as tetrahydrofuran, dioxane, ethylene glycol dimethyl ether, and diethylene glycol dimethyl ether, hydrocarbons such as hexane, heptane, and octane, aromatics such as benzene, toluene, xylene, and cumene, and esters such as ethyl acetate, and butyl acetate.

The acrylic copolymer (D) may be a water-free or solvent-free one, and in this case, the acrylic copolymer (D) is preferably a block copolymer. For example, an acrylic copolymer having a polymer block containing a structural unit derived from an alkyl methacrylate having 1 to 3 carbon atoms in the alkyl group and a polymer block containing a structural unit derived from an alkyl acrylate having 1 to 8 carbon atoms in the alkyl group can be used as the block copolymer. By using such a block copolymer, the cohesive force in the acrylic copolymer (D) is improved, and the effect of improving the adhesive force can be expected.

The block copolymer includes a triblock polymer comprising a hard segment (AH) formed from an alkyl methacrylate having 1 to 3 carbon atoms in the alkyl group and a soft segment (AS) formed from an alkyl acrylate having 1 to 8 carbon atoms in the alkyl group, the triblock polymer being formed by combining the hard segment (AH) with the soft segment (AS) in the form of-AH-AS-AH-, and a diblock polymer being formed by combining the hard segment (AH) with the soft segment (AS). The triblock polymer and the diblock polymer may be used in combination.

The alkyl methacrylate having 1 to 3 carbon atoms in the alkyl group, which is used to form the hard segment of the block copolymer, is preferably methyl methacrylate, ethyl methacrylate, n-propyl methacrylate or isopropyl methacrylate.

Examples of the alkyl acrylate having 1 to 8 carbon atoms in the alkyl group which is used to form the soft block of the block copolymer include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, isopentyl acrylate, hexyl acrylate, and 2 ethylhexyl acrylate.

Specific examples of the block copolymer include kuraritiy LA2140E, kuraritiy LA2250, kuraritiy LA2330, kuraritiy LA3320, kuraritiy LA3170, kuraritiy LA2270, kuraritiy LA4285, kuraritiy LA1892, kuraritiy LK9243, kuraritiy KL-LK9333, and the like.

The adhesive layer (B) contains the acrylic copolymer (D), and may contain a curing agent (E) and/or a tackifier (F) as required.

[ curing agent (E) ]

Examples of the curing agent (E) include isocyanate curing agents, epoxy curing agents, aziridine curing agents, chelate curing agents, and the like.

The isocyanate curing agent is preferably a diisocyanate or a polyisocyanate having 3 or more isocyanate groups, which is obtained by modifying a diisocyanate.

Examples of the diisocyanate include aromatic diisocyanate, aliphatic diisocyanate, and alicyclic diisocyanate.

Examples of the aromatic diisocyanate include 1, 5-naphthylene diisocyanate, 4 '-diphenylmethane diisocyanate, 4' -dibenzyl isocyanate, dialkyldiphenylmethane diisocyanate, tetraalkyl diphenylmethane diisocyanate, 1, 3-phenylene diisocyanate, 1, 4-phenylene diisocyanate, toluene diisocyanate and the like.

Examples of the aliphatic diisocyanate include butane-1, 4-diisocyanate, hexamethylene diisocyanate, isopropenyl diisocyanate, methylene diisocyanate, 2, 4-trimethylhexamethylene diisocyanate, xylylene diisocyanate, and m-tetramethylxylylene diisocyanate.

Examples of the alicyclic diisocyanate include cyclohexane-1, 4-diisocyanate, isophorone diisocyanate, lysine diisocyanate, dicyclohexylmethane-4, 4' -diisocyanate, 1, 3-bis (isocyanatomethyl) cyclohexane, methylcyclohexane diisocyanate, and norbornane diisocyanate.

The polyisocyanate is preferably a so-called adduct obtained by modifying a diisocyanate with a 3-functional polyol component, a biuret obtained by reacting a diisocyanate with water, or a trimer having an isocyanurate ring (isocyanurate) formed from 3-molecule diisocyanate. Examples of the polyisocyanate include trimethylolpropane adduct of xylylene diisocyanate, trimethylolpropane adduct of toluene diisocyanate, biuret of hexamethylene diisocyanate, allophanate of hexamethylene diisocyanate, isocyanurate of isophorone diisocyanate, and the like.

Examples of the epoxy curing agent include 1, 3-bis (N, N ' -diglycidyl aminomethyl) cyclohexane, N, N, N ', N ' -tetraglycidyl-m-xylylenediamine, ethylene glycol diglycidyl ether, 1, 6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidyl aniline, diglycidyl amine, and the like.

Examples of the aziridine curing agent include diphenylmethane-4, 4' -bis (1-aziridine carboxamide), trimethylolpropane tri- β -aziridinyl propionate, tetramethylolmethane tri- β -aziridinyl propionate, toluene-2, 4-bis (1-aziridine carboxamide), triethylenemelamine, bis-m-phthaloyl-1- (2-methylaziridine), tri-1- (2-methylaziridine) phosphine, trimethylolpropane tri- β - (2-methylaziridine) propionate, and the like.

Examples of the chelate-type curing agent include compounds composed of polyvalent metals and ligands, and examples of the polyvalent metals include nickel, aluminum, chromium, iron, titanium, zinc, cobalt, manganese, and zirconium. Examples of the ligand include acetylacetone and acetoacetate.

When the curing agent is used, the content thereof is preferably 0.01 to 10 parts by mass, more preferably 0.1 to 7.5 parts by mass, and even more preferably 0.5 to 5 parts by mass, relative to 100 parts by mass of the nonvolatile component of the adhesive layer. In these ranges, the effect of improving the adhesion, durability, and the like can be expected.

[ tackifier (F) ]

Examples of the tackifier (F) include rosin-based tackifiers (F1), terpene-based tackifiers (F2), coumarin-based tackifiers, styrene-based tackifiers, and petroleum-based tackifiers.

The rosin-based tackifier (F1) includes rosin-based resins, polymerized rosin-based resins, rosin ester-based resins, polymerized rosin ester-based resins, and the like. The terpene-based tackifier (F2) includes terpene-based resins, terpene-phenolic resins, and the like. When the tackifier (F) is used, it is preferably a rosin-based tackifier (F1) or a terpene-based tackifier (F2), and more preferably a rosin-based tackifier (F1). By using these tackifiers (F), an effect of improving the adhesion can be expected.

When the tackifier (F) is used, the content thereof is preferably 1 to 40 parts by mass, more preferably 5 to 40 parts by mass, and even more preferably 15 to 30 parts by mass, relative to 100 parts by mass of the nonvolatile component of the adhesive layer. In these ranges, the adhesion is more easily improved, and a laminate excellent in resealability can be produced.

The adhesive layer of the present invention may further contain, as optional components, flame retardants, heat stabilizers, weather stabilizers, aging inhibitors, ultraviolet absorbers, leveling agents, antistatic agents, slipping agents, antiblocking agents, antifogging agents, lubricants, dyes, waxes, and the like.

< Heat sealing resin layer (C) >)

The heat-sealing resin layer (C) contains a polyethylene-based resin and further contains at least one of a polypropylene-based resin and a polybutylene-based resin. Since the polyethylene resin is incompatible with the polypropylene resin and the polybutylene resin, the incompatible resins coexist in the heat-seal resin layer (C).

Further, as described above, after the heat-seal resin layer (C) is bonded to the container by thermocompression bonding, the heat-seal portion is transferred to the container after the laminate is unsealed. That is, the heat-seal resin layer (C) tears at the heat-seal portion and other portions during unsealing, and if the tearability of the layer is insufficient, the heat-seal resin layer (C) remains at either one of the laminate side and the container side or stringiness in which thread elongation occurs. The polyethylene resin and at least one of the polypropylene resin and the polybutylene resin which are not compatible with the polyethylene resin are contained, whereby the tearing property is improved, and such a phenomenon is less likely to occur.

As the polyethylene resin, for example, low density polyethylene, high density polyethylene, ethylene-vinyl acetate copolymer (EVA) and a copolymer composed of ethylene and at least 1 selected from the group consisting of propylene, butene, pentene, hexene and olefins having carbon chains thereon mixed at an arbitrary ratio can be used. In the copolymer of ethylene and propylene and the copolymer of ethylene and butene, a substance having a propylene or butene content of less than 50 mass% in the total 100 mass% of the monomers is included in the polyethylene-based resin. Among them, from the viewpoint of extrusion lamination processability, low density polyethylene and ethylene-vinyl acetate copolymer (EVA) are preferable, and low density polyethylene is more preferable. Particularly preferred are low density polyethylenes produced by a high pressure process. The ethylene content in the total of 100% by mass of the monomers of the polyethylene resin is preferably 60% or more, more preferably 70% or more.

The polypropylene resin may be a homopolymer of propylene or a copolymer of propylene and at least 1 selected from the group consisting of ethylene, butene, pentene, hexene and olefins having a carbon chain thereon. In the copolymer of ethylene and propylene, a polypropylene resin contains 50 mass% or more of propylene in the total of 100 mass% of monomers. Among them, polypropylene-ethylene copolymer is preferable from the viewpoint of coatability by extrusion lamination. The propylene content in the total of 100% by mass of the monomers of the polypropylene resin is preferably 60% or more, more preferably 70% or more.

The polybutene-based resin may be a homopolymer of 1-butene, 2-butene or isobutylene or a polymer obtained by copolymerization. Further, a copolymer composed of these monomers mixed with at least 1 selected from the group consisting of ethylene, propylene, pentene, hexene or olefins with carbon chains thereon in an arbitrary ratio may be used. In the copolymer of ethylene and butene, a substance having a butene content of 50 mass% or more in 100 mass% of the total of monomers is included in the polybutene-based resin. Among them, 1-butene-ethylene copolymer is preferable from the viewpoint of coatability based on extrusion lamination. The content of butene in the total of 100% by mass of the monomers of the polybutene resin is preferably 60% or more, more preferably 70% or more.

The melt flow rate (hereinafter referred to as MFR) of the polyethylene resin is preferably 0.1 to 30g/10 min, more preferably 0.1 to 20g/10 min, and still more preferably 0.1 to 10g/10 min. If the amount is within the above range, coating can be performed more stably by extrusion lamination. The MFR of the polyethylene resin was measured at 190℃and 21.168N in accordance with JIS K7210.

The MFR of the polypropylene resin or the polybutene resin is preferably 0.1 to 10g/10 min, more preferably 0.5 to 8g/10 min. If the amount is within the above range, coating can be performed more stably by extrusion lamination. The MFR of the polypropylene resin and the polybutylene resin were measured at 230℃and 21.168N in accordance with JIS K7210.

The content of the polyethylene resin is preferably 35 to 70% by mass, more preferably 40 to 65% by mass, and even more preferably 45 to 60% by mass, based on 100% by mass of the heat-sealing resin layer (C). When the polyethylene resin content is 35% by mass or more, coating by extrusion lamination can be performed more stably. In addition, by being 70 mass% or less, the tearability and adhesion of the heat-seal resin layer (C) are easily maintained.

The total content of the polypropylene resin and the polybutene resin is preferably 15 to 40% by mass, more preferably 18 to 35% by mass, and even more preferably 20 to 30% by mass, based on 100% by mass of the heat-sealing resin layer (C). If the ratio is within the above range, it is preferable in terms of tearability of the heat-sealing resin layer (C).

The heat-sealing resin layer (C) may contain other resins and tackifiers as far as the properties thereof are not impaired. Specific examples of the other resins include various elastomers such as maleic acid modified products, ethylene-unsaturated monocarboxylic acid copolymers such as ethylene-acrylic acid copolymers and ethylene- (meth) acrylic acid copolymers, metal salts thereof, styrene-butadiene copolymer elastomers, and hydrogen adducts thereof. The tackifier may be the same as the tackifier (F) which may be contained in the adhesive layer (B). The content of the other resin and the tackifier is preferably 15 mass% or less, more preferably 10 mass% or less, and still more preferably 5 mass% or less in 100 mass% of the heat-seal resin layer (C).

In the heat-sealing resin layer (C), wax may be further added for improving the adhesion to the adhesive layer (B) and improving stringing. Examples of the wax include polyethylene wax, polypropylene wax, ethylene-vinyl acetate copolymer wax, fischer-Tropsch (Fischer-Tropsch) wax, paraffin wax, acidified wax, and maleic acid modified wax. Among them, polyethylene wax is preferable. In the case of containing wax, the content thereof is preferably 8 to 40% by mass, more preferably 12 to 30% by mass, and even more preferably 15 to 25% by mass, in 100% by mass of the heat-sealing resin layer (C). The viscosity of the wax at 140℃is preferably 50 to 10000 mPas, more preferably 60 to 8000 mPas. The viscosity was measured using a B-type viscometer (measurement conditions: 140 ℃ C., no.3 spindle, 12rpm, 30 seconds).

The heat-sealing resin layer (C) may further use additives in order to prevent thermal degradation, thermal decomposition, blocking, proper film processing, extrusion lamination processing, within a range not impairing the performance thereof. Examples of the additives include organic lubricants such as erucamide, inorganic lubricants such as calcium carbonate, antioxidants such as hindered phenol, other antiblocking agents, antistatic agents, fillers, pigments, and the like. The compounding of the additives is carried out, for example, by the following method: the components used in the heat-sealing resin layer (C) are put into a mixing device such as a Henschel mixer or a tumbler mixer, mixed for 5 to 20 minutes, put into an extruder, heated and kneaded, and extruded. The extrudate is typically in the form of pellets that are utilized in subsequent processing steps. Examples of the extruder include, but are not limited to, twin screw extruders and the like. In addition, extrusion is generally carried out at 140 to 200 ℃.

Resealable heat sealed laminate

The resealable heat-seal laminate of the present invention can be obtained, for example, by laminating a heat-seal resin layer (C) or the like on the adhesive layer (B) of the base material (a) on which the adhesive layer (B) is laminated.

The adhesive layer (B) can be formed by applying an adhesive to the substrate (a) by a conventionally known application method, and further performing a drying step in the presence of water and a solvent. As the coating method, for example, a known coating method such as spin coating, spray coating, bar coating, blade coating, roll blade coating, die coating, or gravure coating can be used. The drying step may be performed using a known apparatus such as a hot air oven, an electric oven, or an infrared heater. When the adhesive does not contain water or a solvent, for example, a method in which the adhesive is heated to reduce the viscosity, the adhesive is applied to the substrate (a) by a coating method such as a die coating method, and then the adhesive layer (B) is formed by a cooling step is exemplified. After the adhesive layer (B) is formed, the adhesive layer (B) may be transferred to the subsequent step directly on the same production line, or the release paper and the release film may be laminated on the adhesive layer (B) and wound, and the release paper and the release film may be peeled off on another production line to expose the adhesive layer (B) and then transferred to the subsequent step.

As a method of laminating the heat-seal resin layer (C) on the adhesive layer (B), for example, the following methods are cited: the components used in the heat-seal resin layer (C) are mixed, kneaded by heating with an extruder, extruded, cut into pieces, granulated, and using the granules, a single-layer film is produced by a inflation method, a casting method, or the like, and then the single-layer film is laminated on the adhesive layer (B). Alternatively, the pellets may be melted and directly coated on the adhesive layer (B) using a T-die extrusion apparatus.

Resealable packaging container

The resealable packaging container of the present invention is produced by using the resealable heat-seal laminate of the present invention as a lid material, cutting the container according to the shape of the opening of the container body, and sealing the container body by heat-press-bonding with the opening of the container body. That is, the heat-sealing resin layer (C) of the resealable heat-sealing laminate of the present invention is brought into contact with the bonding surface (also referred to as a flange) of the opening portion of the sealed container, and the two are bonded by heating (heat-sealing). The bonding conditions are preferably 130 to 170 ℃.

The container body is preferably a container body made of polyethylene resin and a container body having an inner surface covered with polyethylene resin.

When the container body is a PET container, the container body and the lid material are preferably thermally bonded at a thermal bonding temperature of 130 to 170 ℃, and the seal strength at normal temperature is preferably in the range of 10 to 20N. The resealable packaging container of the present invention may be, for example, packaged jelly, pudding, yogurt, frozen food, dry snack, cupped brew, and the like.

Examples

The present invention will be described below based on examples, but the present invention is not limited to these examples. In the examples, "part" and "%" represent "part by mass" and "% by mass", respectively.

The glass transition temperature and the weight average molecular weight of the acrylic copolymer (D) were measured as follows.

< determination of glass transition temperature (Tg) ]

The glass transition temperature was measured by the Differential Scanning Calorimetry (DSC) method.

The sample for Tg measurement was obtained by heating the measured resin solution at 150 ℃ for about 15 minutes and drying and solidifying the resin solution.

< determination of weight average molecular weight >

The weight average molecular weight was measured by the method described above, and a polystyrene equivalent obtained by Gel Permeation Chromatography (GPC) was used.

Synthesis of acrylic copolymer (D1)

To 3.15 parts of methyl methacrylate, 32 parts of 2-ethylhexyl acrylate, 64 parts of butyl acrylate and 0.85 part of acrylic acid as monomers were added 1.0 part of Aqualon KH-10 (polyoxyethylene-1- (allyloxymethyl) alkyl ether sulfate ammonium salt, manufactured by first Industrial pharmaceutical Co., ltd.) and 25.1 parts of deionized water as anionic reactive emulsifiers, and the mixture was stirred to obtain an emulsion. The resulting emulsion was placed in a dropping funnel.

45.6 parts of deionized water and 1.0 part of the emulsified product were put into a 4-neck flask equipped with a stirrer, a condenser, a thermometer and the dropping funnel, and the inside of the flask was replaced with nitrogen gas, and the flask was heated to 70℃with stirring. Then, ammonium persulfate was added at a concentration of 10% to start the reaction. After the emulsion was added dropwise over 180 minutes while maintaining the internal temperature at 70 ℃, the internal temperature was further maintained at 70 ℃ with stirring, and the reaction was continued for 1 hour in this state. Then, the mixture was cooled to 65℃and 1.0 part of a 10% aqueous solution of the oxidizing agent "PERBUTYL H-69" (manufactured by Japanese fat and oil Co., ltd.) and 1.0 part of a 10% aqueous solution of the reducing agent "Elbit N" (manufactured by Hibiscus rosacea chemical industry Co., ltd.) were added every 10 minutes, followed by three times of addition, and the reaction was continued for 1 hour. Then, the mixture was cooled and neutralized by adding 25% aqueous ammonia at 30℃to obtain an acrylic copolymer (D1) solution having a nonvolatile content of 50% and a Tg of-45 ℃. The acrylic copolymer (D1) was not dissolved in THF, and thus the weight average molecular weight was judged to be more than 2,000,000.

Synthesis of acrylic copolymer (D2)

An acrylic copolymer (D1) solution having a nonvolatile content of 50% and a Tg of-46℃was synthesized in the same manner as in the acrylic copolymer (D1), except that 5 parts of methyl methacrylate, 90.5 parts of 2-ethylhexyl acrylate and 4.5 parts of acrylic acid were used as monomers, and "HITENOL NF-08" (polyoxyethylene alkyl ether sulfate, manufactured by first Industrial pharmaceutical Co., ltd.) was used as an emulsifier. The acrylic copolymer (D1) was not dissolved in THF, and thus the weight average molecular weight was judged to be more than 2,000,000.

Synthesis of acrylic copolymer (D3)

A polymerization apparatus equipped with a stirrer, a thermometer, a dropper and a reflux condenser was used, and a half of a raw material mixture containing 1 part of methyl methacrylate, 4 parts of isobutyl methacrylate, 4 parts of vinyl acetate, 85.3 parts of butyl acrylate, 5 parts of 2-methoxyethyl acrylate, 0.7 part of 2-hydroxyethyl acrylate, 10 parts of methyl ethyl ketone, 60 parts of ethyl acetate and 0.1 part of benzoyl peroxide was charged into a reaction vessel under a nitrogen atmosphere. In addition, the remaining half of the raw material mixture was added to the dropping layer. Next, heating of the reaction tank was started. After confirming the start of the polymerization reaction, the raw material mixture was added dropwise from a dropper over 1 hour. After the completion of the dropwise addition, the solution polymerization was further continued under reflux for 7 hours. After the completion of the reaction, the mixture was cooled to obtain a 58.8% non-volatile acrylic copolymer (D3) solution. The Tg of the obtained acrylic copolymer (D3) was-47℃and the weight-average molecular weight was 708,000.

Synthesis of acrylic copolymer (D4) and (D5)

The same procedure as for the synthesis of the acrylic copolymer (D3) was repeated except that the composition of the monomer was changed to table 1, to obtain an acrylic copolymer (D4) and (D5) solution having a nonvolatile content of 58.8%. The Tg and weight average molecular weight of the obtained polymer are shown in Table 1.

Synthesis of acrylic copolymer (D6)

The same procedure as for the synthesis of the acrylic copolymer (D3) was repeated except that the composition of the monomer was changed to table 1, the amount of methyl ethyl ketone used was changed to 7 parts, and the amount of ethyl acetate used was changed to 63 parts, to obtain an acrylic copolymer (D6) solution having a nonvolatile content of 58.8%. Tg and weight average molecular weight are shown in Table 1.

Acrylic copolymer (D7), (D8) >

The acrylic copolymers (D7) and (D8) were each prepared as follows.

Acrylic copolymer (D7): kuraritiy LK9243 (methyl methacrylate-2 ethylhexyl acrylate-methyl methacrylate block copolymer, MFR93g/10min, manufactured by colali corporation)

Acrylic copolymer (D8): kuraritiy LA3320 (methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer, MFR6g/10min, manufactured by colali corporation)

The MFR was 190℃and the load of 2.16 kg.

TABLE 1

The abbreviations in table 1 are as follows.

MMA: methyl methacrylate

EA: acrylic acid ethyl ester

2EHA: 2-ethylhexyl acrylate

IBMA: isobutyl methacrylate

VAc: vinyl acetate

BA: acrylic acid n-butyl ester

2MTA: acrylic acid 2-methoxyethyl ester

AA: acrylic acid

2HEA: acrylic acid 2-hydroxy ethyl ester

Example 1: production of laminate

< production of adhesive >

As the solid content, 79.1 parts of the acrylic copolymer D3, 1.1 parts of the curing agent E1, and 19.8 parts of the tackifier F1-1 were blended to prepare an adhesive. The ratio in table 2 shows the solid content ratio.

Production of Single film of Heat-sealing resin layer (C)

53 parts of polyethylene-based resin PE1, 26 parts of polypropylene-based resin PP1 and 21 parts of additive C1 were mixed and premixed in a Henschel mixer for 5 minutes. The premix was fed into a hopper, and fed into an extruder described below using a screw feeder, to produce a resin mixture for the heat-seal resin layer (C).

Extruder Condition

And (3) an extruder: IKG company co-rotating double screw extruder PMT32-40.5

Barrel temperature: 180 ℃ (160 ℃ C. Of supply port)

Screw rotation speed: 200rpm

Feed rate: 10kg/hr

The obtained mixture was subjected to inflation molding by a Labtech inflation molding machine (die diameter: 40 mm. Phi., molding temperature: 130 ℃ C.) to prepare a single-layer film of the heat-seal resin layer (C) having a thickness of 20. Mu.m.

Single layer Forming Condition

Inflation molding machine: manufactured by Labtech

Resin temperature: 130 DEG C

Barrel temperature: 180 ℃ (170 ℃ C. Of supply port)

Screw rotation speed: 60rpm

Stretching speed: 5 m/min

Chill roll surface temperature: 20 DEG C

< manufacturing of laminate >

The obtained adhesive was applied to a corona-treated surface of a 12 μm biaxially stretched PET film as a base material (A) by a roll coater, and the solvent was removed by an oven at 100℃to form an adhesive layer (B) having a thickness of 20. Mu.m. Next, a single-layer film of the heat-seal resin layer (C) was laminated on the surface of the adhesive layer (B), to obtain a laminate of example 1 in which the base material (a)/the adhesive layer (B)/the heat-seal resin layer (C) were laminated in this order.

TABLE 2

TABLE 3

Styrene copolymer (S)

S1: kraton G-1657 (styrene-ethylene butadiene-styrene Block copolymer, manufactured by Japanese Korea Polymer Co., ltd., MFR22g/10 min)

S2: kraton G-1652 (styrene-ethylene butadiene-styrene Block copolymer, manufactured by Japanese Kort Polymer Co., ltd., MFR5g/10 min)

The MFR was set at 230℃and 5 kg.

Curing agent (E) >)

E1: the trimethylolpropane adduct of xylylene diisocyanate was diluted with ethyl acetate to a nonvolatile content of 50%: isocyanate curing agent

E2: the trimethylolpropane adduct of toluene diisocyanate was diluted with ethyl acetate to a nonvolatile content of 40%: isocyanate curing agent

E3: tetra d-X (multifunctional epoxy resin manufactured by mitsubishi gas chemical company) was diluted with MEK to a nonvolatile content of 10%: epoxy curing agent

< tackifier (F) >)

F1-1: PINECRYSTAL KE-359 (rosin derivative, manufactured by Sichuan chemical Co., ltd.)

F1-2: PENSEL D-125 (rosin ester manufactured by Sichuan chemical Co., ltd.)

F2-1: YS RESIN PX-1000 (terpene RESIN manufactured by Yasuhara Chemical Co., ltd.)

F3: alcon P-100 (hydrogenated Petroleum resin manufactured by Sichuan chemical Co., ltd.)

F4: kristalex F-100 (styrene-alpha methyl styrene copolymer manufactured by Islaman chemical Co., ltd.)

< liquid component (L) >)

L1: DIANA PROCESS PW-32 (mineral oil manufactured by Kui-Zhou Xing Co., ltd.)

L2: styrene monomer (manufactured by Kanto chemical Co., ltd.)

< other additives (P) >)

P1: MS-P (inorganic substance, manufactured by Japanese talc Co., ltd., average particle size of 14 μm)

Polyethylene resin >, and

PE1: PETROTHENE 213 (Low Density polyethylene, manufactured by Tosoh Co., ltd., MFR8g/10 min)

PE2: urutoasen 526 (ethylene-vinyl acetate copolymer, manufactured by Tosoh Co., ltd., vinyl acetate content 7%, MFR25g/10 min)

The MFR was 190℃and the load of 2.16 kg.

Polypropylene resin and polybutene resin

PP1: SB-520 (polypropylene-polyethylene copolymer, manufactured by LOTTE Co., ltd., MFR1.8g/10 min)

PB1: TAFMER BL-4000 (butene-ethylene copolymer, MFR1.8g/10min, manufactured by Mitsui chemical Co., ltd.)

The MFR was 190℃and the load of 2.16 kg.

Additive (C) >, of

C1: L-C121N (polyethylene wax, manufactured by LIONCHEMTECH Co., ltd., melting point 109 ℃ C.)

Example 1: manufacturing of resealable packaging Container

After being overlapped with a flange portion (width: about 4 mm) around the opening portion of a cylindrical paper container (outer diameter: 95 mm. Phi.) having a polyethylene film laminated inside, the laminate obtained in example 1 was heat-sealed at a sealing temperature of 150℃under a sealing pressure of 100kgf/cup for 1 second using MODEL2005 (manufactured by Towa Techno Co.).

(1) Unsealing strength

The adhesive strength of the resealable packaging container was measured by using a tensile tester (Autograph AGS-X, manufactured by Shimadzu corporation) at a temperature of 23℃and a relative humidity of 65% (65% RH), and the maximum value was read when the laminate was peeled off by about 50% at an opening angle of 90 degrees and an opening speed of 300 mm/min.

And (3) the following materials: 12N or more and less than 20N: very good

O: 9N or more and less than 12N, or 20N or more and less than 23N: good quality

Delta: 6N or more and less than 9N, or 23N or more and less than 26N: can be used

X: less than 6N, or 26N or more: can not be used

(2) Wire drawing

The peeled portion of the laminate from the container after the measurement of the unsealing strength of the resealable packaging container was visually observed, and the occurrence of stringiness was confirmed.

And (3) the following materials: no stringing (0% of the area of the peeled portion where stringing occurs): very good

O: the area of the peeling portion is greater than 0% and less than 10% of the area of the wire drawing portion: good quality

Delta: the area of the peeling portion is greater than 10% and less than 30% of the area of the portion where the wire drawing occurs: can be used

X: of the areas of the peeling portions, the area of the portion where the wire drawing occurs is greater than 30%: can not be used

(3) Cracking (zipper)

Confirming the occurrence of zipper in the measurement of the opening strength of the resealable packaging container.

And (3) the following materials: no cracking (the area of the peeled portion was 0%) was found: very good

O: the area of the peeled portion is greater than 0% and 10% or less of the area of the portion where cracking occurs: good quality

Delta: the area of the peeled portion is greater than 10% and 30% or less of the area of the portion where cracking occurs: can be used

X: of the areas of the peeled portions, the area of the portion where cracking occurred was greater than 30%: can not be used

(4) Resealing

The laminate after the measurement of the unsealing strength of the resealable packaging container is overlapped with the peeled portion of the container, and the sealed laminate is repeatedly pressed with fingers twice to measure the unsealing strength again. This operation was repeated 5 times, and the maximum value of the 5 th time was read.

And (3) the following materials: 4N or more and less than 7N: very good

O: 2N or more and less than 4N, 7N or more and less than 10N: good quality

Delta: 1N or more and less than 2N, 10N or more and less than 13N: can be used

X: less than 1N, or 13N or more: can not be used

(5) Bleeding out to the surface of the heat-sealing resin layer (C) with time

After 40 to 24 hours elapsed, the laminate was visually inspected and compared with the laminate before the elapsed time to confirm the change in the surface state.

O: no change was made: good quality

X: surface wetting, tackiness: can not be used

(6) Resealing after time

A resealable packaging container was obtained by heat-sealing the laminate and a cylindrical paper container having a polyethylene film laminated inside in the same manner as described above, except that the laminate was used after 40 to 24 hours. The resealable packaging container was peeled off by about 50% at an opening angle of 90 degrees and an opening speed of 300 mm/min using a tensile tester (Autograph AGS-X, shimadzu corporation) at 23℃under a relative humidity of 65% (65% RH). Next, the unsealed laminate of the resealable packaging container was overlapped with the peeled portion of the container, and the laminate was sealed by repeatedly pressing with fingers twice, and then the unsealing strength was measured again. This operation was repeated 5 times, and the maximum value of the 5 th time was read. Using this value and the reseal evaluation value when the stack was used without time, the following relative ratio was obtained and evaluated as follows.

Relative ratio (%) =100× (evaluation value of resealing when using a laminate without time)/(evaluation value of resealing when using a laminate after 40-24 hours elapsed)

O: the relative ratio is more than 70 percent: can be used

X: the relative ratio is less than 70%: can not be used

Examples 2 to 15

A laminate and a resealable packaging container were produced and evaluated in the same manner as in example 1, except that the compositions and ratios of the adhesives were changed as shown in tables 2 and 3 in examples 2 to 15.

Example 16: production of laminate

< production of adhesive >

65 parts of the acrylic copolymer D7, 15 parts of the tackifier F3 and 20 parts of the tackifier F4 were mixed by a Henschel mixer and premixed for 5 minutes. The premix was charged into a hopper, and fed to an extruder described below using a screw feeder, to produce an adhesive.

Extruder Condition

And (3) an extruder: IKG company co-rotating double screw extruder PMT32-40.5

Barrel temperature: 180 ℃ (160 ℃ C. Of supply port)

Screw rotation speed: 200rpm

Feed rate: 10kg/hr

< manufacturing of laminate >

On the corona-treated surface of a 12 μm biaxially stretched PET film as a base material layer, an adhesive was extruded from a T die so as to have a thickness of 20 μm, and a single-layer film of a heat-seal resin layer (C) was laminated on the surface of an adhesive layer (B), whereby a laminate was obtained by the above sandwich lamination method, in which the base material (a)/the adhesive layer (B)/the heat-seal resin layer (C) were laminated in this order.

Example 16: manufacturing of resealable packaging Container

In the same manner as in example 1, a resealable packaging container was produced and evaluated.

Example 17

A laminate and a resealable packaging container were produced and evaluated in the same manner as in example 16, except that the composition and the ratio of the adhesive agent in example 17 were changed to those in table 3.

Examples 18 to 20

A laminate and a resealable packaging container were produced and evaluated in the same manner as in example 1, except that the compositions and ratios of the adhesive and the heat-sealing resin layer (C) were changed to those shown in table 3 in examples 18 to 20.

Comparative example 1: production of laminate

< production of adhesive >

35 parts of liquid component L1 (mineral oil) was mixed in a stainless steel beaker equipped with a stirrer, and the mixture was heated and stirred to 160 ℃. While stirring, 1.30 parts of a styrene-based elastomer S and a tackifier F3 were mixed, and stirred for 3 hours to obtain a hot-melt adhesive.

< manufacturing of adhesive layer >

The hot-melt adhesive heated to 160℃was applied to the corona-treated surface of a 12 μm biaxially stretched PET film as the substrate (A) by a hand coater to form an adhesive layer (B) having a thickness of 30 μm, thereby obtaining a substrate (A)/adhesive layer (B) laminate.

< manufacturing of laminate >

A single-layer film of the heat-seal resin layer (C) was laminated on the surface of the adhesive layer (B) of the substrate (a)/adhesive layer (B) laminate, to obtain a laminate in which the substrate (a)/adhesive layer (B)/heat-seal resin layer (C) were laminated in this order.

Comparative example 1: manufacturing of resealable packaging Container

In the same manner as in example 1, a cup seal was produced and evaluated.

Comparative example 2

A laminate and a cup seal were produced and evaluated in the same manner as in example 16 except that the composition and the ratio of the adhesive were changed to those of table 3.

Comparative example 3, 4

A laminate and a cup seal were produced and evaluated in the same manner as in example 1 except that the compositions and ratios of the adhesive and the heat-seal resin layer (C) were changed to those shown in table 3 in comparative examples 3 and 4.

As shown in tables 2 and 3, examples 1 to 20 in which the adhesive layer (B) contains the acrylic copolymer (D) and the heat-sealing resin layer (C) contains the polyethylene resin and further contains at least one of the polypropylene resin and the polybutylene resin, respectively, show that: when the lid material is peeled from the container, a part of the heat-seal resin layer (C) is not likely to remain in the heat-seal portion on the lid material side or is not likely to be pulled into a wire shape (drawn) to exhibit sufficient initial unsealing strength, and even after unsealing, the lid material and the container can be pressed to reseal with practically sufficient strength, and further, bleeding of liquid components on the surface of the laminate with the lapse of time is prevented.

Claims (5)

1. A resealable heat-seal laminate comprising a base material (A), an adhesive layer (B) and a heat-seal resin layer (C) arranged in this order,

the adhesive layer (B) contains an acrylic copolymer (D),

the heat-sealing resin layer (C) contains a polyethylene-based resin and further contains at least one of a polypropylene-based resin and a polybutylene-based resin.

2. The resealable heat seal laminate according to claim 1, the adhesive layer (B) further comprising a curing agent (E).

3. The resealable heat seal laminate according to claim 1, the adhesive layer (B) further comprising a tackifier (F).

4. A resealable heat seal laminate according to claim 3, wherein the tackifier (F) comprises a rosin-based tackifier (F1) or a terpene-based tackifier (F2).

5. A resealable packaging container having the resealable heat seal laminate and container body of any one of claims 1-4.