Multilayer film with re-sealing function, multilayer body with re-sealing function, and package with re-sealing function

Abstract

To provide a multilayer film with a re-sealing function which is excellent in initial peeling strength when being opened and re-sealing strength when being re-opened.SOLUTION: There is provided a multilayer film with a re-sealing function in which an adhesive resin layer (A) and a peeling resin layer (B) are directly stacked, wherein the adhesive resin layer (A) contains a styrene-isobutylene-styrene copolymer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a resealable multilayer film, and more specifically to a resealable multilayer film that is suitable for packaging foods, medicines, etc., a resealable multilayer body using the same, and a resealable package. [Background technology]

[0002] BACKGROUND ART Conventionally, various types of resealable packaging have been used as packaging means for cosmetics and sanitary products that are repeatedly opened and resealed each time they are used, or for food and medicines in quantities that cannot be consumed in one go. Such packages can prevent the contents remaining after opening from deteriorating due to oxidation or deterioration due to moisture absorption or drying, and for example, zipper-type packages in which a plastic zipper is laminated are known. Although such packaging can be opened repeatedly and has excellent durability, it requires special equipment to attach accessories such as zippers to the packaging, and the associated processing steps are also required, which results in problems such as increased manufacturing costs and reduced production efficiency.

[0003] On the other hand, multilayer films have also been developed that can impart a resealable function to the packaging itself without the need for attachments such as zippers. For example, Patent Document 1 discloses a multilayer film comprising a surface resin layer, an adhesive resin layer containing a hydrogenated styrene-diene rubber block copolymer and a tackifier, and a heat-sealable resin layer, in which, when the multilayer film is peeled off from a base material, the adhesive resin layer is exposed in an adhesive state at the heat-sealed portion that allows for resealing.

[0004] Furthermore, Patent Document 2 discloses a package using, as a lid material for a container, a multilayer film comprising a surface resin layer, an adhesive resin layer containing a hydrogenated styrene-diene rubber block copolymer and a tackifier, and a heat-sealable resin layer, wherein when the heat-sealable resin layer and a heat-sealable thermoplastic resin layer are heat-sealed together and then peeled apart, the heat-sealable resin layer ruptures and the heat-sealable resin layer and the adhesive resin layer peel apart, exposing the adhesive resin layer in a resealable adhesive state at the heat-sealed portion.

[0005] Furthermore, Patent Document 3 discloses a package using a multilayer film as a base material, characterized in that a peel layer is provided between the heat seal layer and the adhesive resin layer to heat seal the heat seal resin layer and a heat-sealable thermoplastic resin layer, and when the layers are subsequently peeled away, the heat seal resin layer and the peel layer rupture and the peel layer and the adhesive resin layer peel away from each other, exposing the adhesive resin layer in an adhesive state at the heat seal portion that allows for resealing. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-175567 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-75181 [Patent Document 3] Japanese Patent Application Laid-Open No. 2008-200960 Summary of the Invention [Problem to be solved by the invention]

[0007] The multilayer films described in Patent Documents 1 to 3 have a resealing function, but the balance between the initial peel strength when opened and the resealing peel strength when resealed is insufficient, and there is room for further improvement.

[0008] The present invention has been made in consideration of the above-mentioned circumstances, and its object is to provide a multilayer film with a resealable function that has excellent initial peel strength when opened and resealable strength when resealed, and a resealable package using the same. [Means for solving the problem]

[0009] As a result of intensive research to solve the above-mentioned problems, the inventors have found that the above-mentioned problems can be solved by using a styrene-isobutylene-styrene copolymer in the adhesive resin layer of a multilayer film in which an adhesive resin layer and a release resin layer are laminated in that order, and have thus completed the present invention.

[0010] That is, the present invention has the following aspects. [1] A resealable multilayer film in which an adhesive resin layer (A) and a release resin layer (B) are directly laminated together, wherein the adhesive resin layer (A) contains a styrene-isobutylene-styrene copolymer. [2] The resealable multilayer film according to [1], wherein the glass transition temperature of the styrene-isobutylene-styrene copolymer is −35° C. or lower. [3] The resealable multilayer film according to [1] or [2], wherein the release resin layer (B) contains a polypropylene-based resin. [4] The resealable multilayer film according to any one of [1] to [3], further comprising a resin layer (C), the resin layer (C) containing at least one thermoplastic resin selected from polyolefin resins, polyamide resins, ethylene-vinyl alcohol copolymers, polyester resins, and polystyrene resins. [5] The resealable multilayer film according to [4], wherein the resin layer (C) has an ethylene-vinyl alcohol copolymer layer and / or a polyamide resin layer. [6] The resealable multilayer film according to any one of [1] to [5], further comprising a heat seal layer (D) on the surface side of either the adhesive resin layer (A) or the release resin layer (B). [7] A multilayer film with resealable function according to any one of [1] to [6], wherein when the resealable multilayer film and an object to be sealed are heat-sealed and the resealable multilayer film is peeled off from the object, interlayer delamination occurs between the adhesive resin layer (A) and the peelable resin layer (B), exposing the adhesive resin layer (A), thereby making the adhesive resin layer (A) and the peelable resin layer (B) resealable. [8] A resealable multilayer body obtained by heat-sealing the resealable multilayer film according to any one of [1] to [7] and an object to be sealed. [9] A multilayer body with resealable function described in [8], in which, when the resealable multilayer film is peeled from the resealable multilayer body, the adhesive resin layer (A) or the peelable resin layer (B) of the resealable multilayer film breaks and interlayer delamination occurs between the adhesive resin layer (A) and the peelable resin layer (B).

[10] A resealable package using the resealable multilayer body described in [8] or [9]. [Effects of the Invention]

[0011] The resealable multilayer film of the present invention has excellent initial peel strength when opened and excellent reseal strength when resealed. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a partial cross-sectional view of a package using the resealable multilayer film of the present invention as a lid material. [Figure 2] 2 is a partial cross-sectional view of the package shown in FIG. 1 with a portion of the lid peeled off from the container. [Figure 3] 2 is a partial cross-sectional view showing the state in which the lid and base members of the package shown in FIG. 1 have been resealed. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0013] The present invention will be described below based on examples of embodiments for carrying out the present invention, but the present invention is not limited to the embodiments described below.

[0014] In this specification, "X and / or Y (X and Y are any configurations)" means at least one of X and Y, and means three possibilities: X only, Y only, and X and Y. When expressed as "X to Y" (X and Y are any numbers), unless otherwise specified, it means "X or more and Y or less," as well as "preferably greater than X" or "preferably smaller than Y." When expressed as "X or more" (X is any number) or "Y or less" (Y is any number), it also means that "it is preferably greater than X" or "it is preferably less than Y." In the present specification, when numerical ranges are described in stages, the upper or lower limit of a certain numerical range can be arbitrarily combined with the upper or lower limit of another numerical range. In addition, in the numerical ranges described in this specification, the upper or lower limit of the numerical range can also be replaced with the values ​​shown in the examples. In this specification, the term "main component" means a component that has a significant effect on the properties of the target object, and the content of the component is usually 50% by mass or more in the target object, preferably 55% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, particularly preferably 80% by mass, and may be 100% by mass. In this specification, the term "film" encompasses a wide range of materials from thick sheets to thin films.

[0015] A multilayer film with resealable function according to one embodiment of the present invention (hereinafter sometimes referred to as "the multilayer film") comprises an adhesive resin layer (A) and a release resin layer (B) directly laminated together, and the adhesive resin layer (A) contains a styrene-isobutylene-styrene copolymer.

[0016] In addition to the adhesive resin layer (A) and the release resin layer (B), the present multilayer film may also have, for example, a resin layer (C), a heat seal layer (D), etc. The present multilayer film may have one of these layers or two or more layers.

[0017] When this multilayer film is heat-sealed to an object to be sealed and the heat-sealed portion is peeled off, delamination occurs between the adhesive resin layer (A) and the peelable resin layer (B), exposing the adhesive resin layer (A), making the adhesive resin layer (A) and the peelable resin layer (B) resealable. Each layer will be described below.

[0018] <Adhesive resin layer (A)> The adhesive resin layer (A) contains a styrene-isobutylene-styrene copolymer (SIBS), preferably containing SIBS as a main component. The SIBS may be used alone or in combination of two or more. Examples of the SIBS include "SIBS ATR" manufactured by Kaneka Corporation.

[0019] The styrene content of the SIBS is usually 30% by mass or less, preferably 25% by mass or less. If the styrene content is too high, the resealing strength tends to decrease. The lower limit of the styrene content is usually 1% by mass or more, preferably 3% by mass or more, and more preferably 5% by mass or more.

[0020] The glass transition temperature (ISO 11357-2) of the SIBS is preferably −35° C. or lower, more preferably −90 to −40° C., still more preferably −80 to −45° C., and particularly preferably −70 to −50° C. When the glass transition temperature of the SIBS is within the above range, the resealability tends to be better. Furthermore, when two or more types of SIBS are used, it is preferable that the glass transition temperature of the SIBS (or SIBSs) contained in the largest amount is within the above range, and it is more preferable that the glass transition temperatures of all the SIBSs contained are within the above range.

[0021] The melt flow rate [MFR] of the SIBS (JIS K7210, 230°C, load 2.16 kg) is usually 0.1 to 100 g / 10 min, preferably 0.2 to 50 g / 10 min. When the MFR of the SIBS is within the above range, film formability tends to be stable.

[0022] The weight average molecular weight of the SIBS is usually 50000 to 300000, and preferably 70000 to 260000. By setting the weight average molecular weight within the above range, film formability tends to be stable. The weight average molecular weight is determined by gel permeation chromatography in terms of the molecular weight of standard polystyrene.

[0023] The adhesive resin layer (A) may contain a thermoplastic elastomer other than the SIBS, such as a styrene-based thermoplastic elastomer or an olefin-based thermoplastic elastomer, in order to enhance the resealability. These may be used alone or in combination of two or more kinds.

[0024] Examples of the styrene-based thermoplastic elastomer include styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), and hydrogenated versions thereof such as styrene-ethylene-butadiene-styrene block copolymer (SEBS) and styrene-ethylene-propylene-styrene block copolymer (SEPS). Among these, SEBS and SEPS are preferred because of their excellent dispersibility with SIBS. Commercially available products of these styrene-based thermoplastic elastomers include "Tufprene," "Asaprene T," "Tuftec," "SOE," and "Asaflex" manufactured by Asahi Kasei Corporation, "Septon" and "Hybra" manufactured by Kuraray Co., Ltd., and "KRATON A," "KRATON D," and "KRATON G" manufactured by Kraton.

[0025] The styrene content of the styrene-based thermoplastic elastomer is usually 3 to 80 mass %, preferably 50 to 70 mass %, more preferably 5 to 50 mass %, and even more preferably 10 to 30 mass %. When the styrene content is within the above range, the resealing strength tends to be excellent.

[0026] The melt flow rate [MFR] (JIS K7210, 230°C, 2160g load) of the styrene-based thermoplastic elastomer is usually 0.1 to 100g / 10min, preferably 0.2 to 50g / 10min. When the MFR of the styrene-based thermoplastic elastomer is within the above range, film formability tends to be stable.

[0027] The olefin-based thermoplastic elastomer is a thermoplastic elastomer resin that uses polyolefin (polyethylene, polypropylene, etc.) as a hard segment and aliphatic rubber as a soft segment.

[0028] Examples of the aliphatic rubber include diene rubbers such as isoprene rubber, butadiene rubber, butyl rubber, propylene-butadiene rubber, acrylonitrile-butadiene rubber, and acrylonitrile-isoprene rubber; ethylene-propylene non-conjugated diene rubber; and ethylene-butadiene copolymer rubber.

[0029] The olefin-based thermoplastic elastomers include those synthesized by compounding polyolefins with aliphatic rubbers (compound type), or by introducing aliphatic rubbers during olefin polymerization (reactor type). The compound type includes simple blends (non-crosslinked types) and dynamically crosslinked products (fully crosslinked or partially crosslinked types). In addition, in this embodiment, polyolefins that do not contain a rubber component but have a certain degree of flexibility and have a relatively low density or a low degree of crystallinity are also included in the olefin-based thermoplastic resin elastomer. Examples of such polyolefins include low-crystalline ethylene-α-olefin random copolymers obtained by randomly copolymerizing two or more olefin monomers such as ethylene, propylene, and butene. Specific examples include the TAFMER series (product names) manufactured by Mitsui Chemicals, Inc., such as ethylene-based TAFMER, propylene-based TAFMER, and butene-based TAFMER. Among these, low-crystalline ethylene-α-olefin random copolymers are preferred as olefin-based thermoplastic elastomers.

[0030] The density of the olefin-based thermoplastic elastomer is usually 0.890 g / cm 3 or less, preferably 0.820 to 0.890 g / cm 3 It is preferable that:

[0031] The melt flow rate [MFR] (JIS K7210, 230°C, load 2160 g) of the olefin-based thermoplastic elastomer is usually 0.01 to 150 g / 10 min, preferably 0.1 to 50 g / 10 min, more preferably 1 to 25 g / 10 min, and even more preferably 2 to 10 g / 10 min.

[0032] When the adhesive resin layer (A) contains a thermoplastic elastomer, the content thereof is usually less than 50% by mass, preferably 40% by mass or less, and more preferably 30% by mass or less. If the content of the thermoplastic elastomer is within the above range, interfacial peeling with the release resin layer (B) tends to occur easily.

[0033] The adhesive resin layer (A) may contain a tackifier, which tends to improve the resealing strength.

[0034] The tackifier may be any natural or synthetic resin that is tacky at room temperature (25°C), including, for example, rosin-based resins such as natural resin rosin, polymerized rosin, hydrogenated rosin, pentaerythritol esters of rosin, and glycerin esters of rosin; terpene-based resins such as terpene-phenol resins, terpene resins (α-pinene resins, β-pinene resins), aromatic-modified terpene resins, and hydrogenated terpene resins; petroleum-based hydrocarbon resins such as aromatic hydrocarbon resins, aliphatic hydrocarbon resins, aliphatic cyclic hydrocarbon resins, aliphatic-alicyclic petroleum resins, aliphatic-aromatic petroleum resins, unsaturated hydrocarbon copolymers, and hydrogenated hydrocarbon resins; phenol-based resins such as phenol-formaldehyde resins and xylene-formaldehyde resins; and chroman resins such as chroman-indene resins. These may be used alone or in combination of two or more. Among these, from the viewpoint of compatibility with SIBS, rosin-based resins, terpene-based resins, and petroleum-based hydrocarbon resins are preferred, rosin-based resins are more preferred, and hydrogenated rosin is particularly preferred. Commercially available tackifiers include the "Haritack Series" manufactured by Harima Chemical Co., Ltd., the "YS Resin Series" manufactured by Yasuhara Chemical Co., Ltd., and the "Super Ester Series," "Ester Gum Series," "Persene Series," and "Arcon Series" manufactured by Arakawa Chemical Industries, Ltd.

[0035] The softening point (JIS K5902) of the tackifier is usually 20 to 180° C., preferably 50 to 140° C., and more preferably 70 to 110° C. When the softening point of the tackifier is within the above range, the resealing function tends to be more excellent.

[0036] When the adhesive resin layer (A) contains a tackifier, the content thereof is usually less than 40% by mass, preferably 1 to 30% by mass, and more preferably 5 to 25% by mass. When the content of the tackifier is within the above range, the resealing strength tends to be better.

[0037] Other components may be added to the adhesive resin layer (A) as appropriate within the scope of the present invention. Examples of the other components include softeners, oils (mineral oils), stabilizers (antioxidants, etc.), liquid paraffin, etc. These may be used alone or in combination of two or more.

[0038] The glass transition temperature (Tg) of the adhesive resin layer (A) is preferably −35° C. or lower from the viewpoint of resealing peel strength, more preferably −40° C. or lower, and particularly preferably −45° C. or lower. The lower limit is not particularly limited, but is usually −90° C., preferably −80° C. The glass transition temperature (Tg) of the adhesive resin layer (A) is measured by differential scanning calorimetry (DSC).

[0039] The adhesive resin layer (A) is a resin layer having a single layer configuration, and its thickness is not particularly limited, but is usually 3 to 100 μm, preferably 5 to 80 μm, and more preferably 10 to 70 μm. By setting the thickness of the adhesive resin layer (A) within the above range, film formability is stable and strength is also appropriate.

[0040] <Release Resin Layer (B)> The release resin layer (B) in the present embodiment is preferably a layer containing a thermoplastic resin, and more preferably contains a thermoplastic resin as a main component.

[0041] Examples of the thermoplastic resin include polyolefin resins, polyamide resins, polyester resins, etc. These may be used alone or in combination of two or more.

[0042] [Polyolefin resin] Examples of the polyolefin resin include polyethylene resin (PE), polypropylene resin (PP), α-olefin copolymer, cyclic polyolefin resin, and modified polyolefin resin.

[0043] [Polyethylene resin] Examples of the polyethylene resin include resins containing ethylene structural units as a main component, such as very low density polyethylene (VLDPE), linear low density polyethylene (LLDPE), low density polyethylene (LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), ethylene-vinyl acetate copolymer (EVA), etc. Among these, LLDPE, LDPE, MDPE, and HDPE are preferred, and MDPE and HDPE are more preferred, from the viewpoint of releasability from the adhesive resin layer.

[0044] The melting point (JIS K7121) of the polyethylene resin is usually 100°C or higher, preferably 110°C or higher, and more preferably 120°C or higher.

[0045] [Polypropylene resin] Examples of the polypropylene resin include resins containing propylene structural units as the main component, such as propylene homopolymers (homopolypropylenes) and copolymers of propylene with other α-olefins, such as ethylene and butene. Either random copolymers or block copolymers can be used as the copolymers. Furthermore, the stereoregularity may be any of an isotactic structure, a syndiotactic structure, an atactic structure, a stereoblock structure, etc. These may be used singly or in combination of two or more.

[0046] The melting point (JIS K7121) of the polypropylene resin is usually 120°C or higher, preferably 130°C or higher, and more preferably 140°C or higher.

[0047] [α-olefin copolymer] Examples of the α-olefin copolymer include copolymers of α-olefins having 2 to 10 carbon atoms, such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, and 1-octene. Specific examples include ethylene-α-olefin copolymers, propylene-α-olefin copolymers, and ethylene-propylene-α-olefin copolymers.

[0048] [Cyclic polyolefin resin] Examples of the cyclic polyolefin resin include random copolymers of ethylene and cyclic olefins such as norbornenes, tetracyclododecenes, and derivatives thereof, cyclic olefin ring-opening polymers, cyclic olefin ring-opening copolymers, hydrogenated cyclic olefin ring-opening polymers and cyclic olefin ring-opening copolymers, and graft-modified products of these polymers or copolymers. Here, in the case of random copolymers of ethylene and cyclic olefins, they may contain an α-olefin other than ethylene, or may contain butadiene, isoprene, or the like as a third component.

[0049] [Modified polyolefin resin] Examples of the modified polyolefin resin include the above-mentioned polyethylene resin, polypropylene resin, and resins obtained by modifying an α-olefin copolymer with an unsaturated carboxylic acid and / or an unsaturated carboxylic acid derivative.

[0050] Examples of the unsaturated carboxylic acid and / or unsaturated carboxylic acid derivative include unsaturated carboxylic acids such as maleic acid, fumaric acid, itaconic acid, acrylic acid, and methacrylic acid, and unsaturated carboxylic acid derivatives such as maleic anhydride, itaconic anhydride, methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-hydroxyethyl methacrylate, maleic acid monoethyl ester, maleic acid diethyl ester, fumaric acid monomethyl ester, fumaric acid dimethyl ester, acrylamide, methacrylamide, maleic acid monoamide, maleic acid diamide, fumaric acid monoamide, maleimide, N-butylmaleimide, and sodium methacrylate. Among these, acrylic acid, methacrylic acid, maleic acid, and maleic anhydride are preferred from the viewpoint of excellent adhesiveness.

[0051] Specific examples of modified polyolefin resins include ethylene-acrylic acid copolymer (EAA), ethylene-methacrylic acid copolymer (EMAA), ethylene-methyl acrylate copolymer (EMA), ethylene-methyl methacrylate copolymer (EMMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-glycidyl methacrylate copolymer (E-GMA), ethylene-vinyl acetate-glycidyl methacrylate copolymer (E-VA-GMA), ethylene-maleic anhydride copolymer (E-MAH), propylene-maleic anhydride copolymer, ethylene-ethyl acrylate-maleic anhydride copolymer (E-EA-MAH), metal-neutralized ethylene-acrylic acid copolymer, and metal-neutralized ethylene-methacrylic acid copolymer.

[0052] The density of the modified polyolefin resin (JIS K7121) is usually 0.870 g / cm 3 or more, preferably 0.880 to 0.950 g / cm 3 is. The melting point (JIS K7121) of the modified polyolefin resin is usually 100°C or higher, preferably 120°C or higher, and although there are no particular upper limits, it is usually 170°C or lower.

[0053] [Polyamide resin] Examples of the polyamide resin include aliphatic polyamide polymers and aromatic polyamide polymers.

[0054] Examples of the aliphatic polyamide polymer include ring-opening polymerization products of cyclic lactams, polycondensation products of aminocarboxylic acids, polycondensation products of dicarboxylic acids and diamines, etc. Specific examples include a homopolymer of ε-caprolactam called nylon 6, polyhexamethylene adipamide called nylon 66, and a copolymer thereof called nylon 6-66. Furthermore, examples of the aromatic polyamide polymer include resins containing, in the molecular chain, 70 mol% or more of polyamide structural units composed of xylylenediamine and an α,ω-aliphatic dicarboxylic acid having from 6 to 12 carbon atoms. Specific examples include homopolymers such as polymetaxylylene adipamide, polymetaxylylene pimelamide, polymetaxylylene azelamide, polyparaxylylene azelamide, and polyparaxylylene decanamide, and copolymers such as metaxylylene / paraxylylene adipamide copolymer, metaxylylene / paraxylylene pimelamide copolymer, metaxylylene / paraxylylene azelamide copolymer, and metaxylylene / paraxylylene sepacamide copolymer. These polyamide resins may be used singly or in combination of two or more.

[0055] [Polyester Resin] Examples of the polyester resin include polyethylene terephthalate resin, polypropylene terephthalate resin, polybutylene terephthalate resin, polyethylene isophthalate resin, polyethylene naphthalate resin, polybutylene naphthalate resin, polyethylene terephthalate / isophthalate copolymer resin, low-crystalline or amorphous polyethylene terephthalate resin containing 15 mol % to 50 mol % of 1,4-cyclohexanedimethanol structural units in total glycol monomer units, polyethylene / neopentyl terephthalate copolymer resin, and aliphatic polyester resins typified by polylactic acid resin.

[0056] The polyester resin also includes a thermoplastic polyester elastomer having a high melting point, highly crystalline aromatic polyester as a hard segment and an amorphous polyester or amorphous polyether as a soft segment.

[0057] Among these thermoplastic resins, resins that do not fuse with the adhesive resin layer (A) upon heat sealing are preferred, more preferably polyolefin-based resins, polyamide-based resins, and polyester-based resins, even more preferably polyethylene-based resins, polypropylene-based resins, and polyethylene terephthalate-based resins, particularly preferably polypropylene-based resins, and especially preferably homopolypropylene-based resins.

[0058] That is, in this embodiment, it is particularly preferable to use a polypropylene-based resin layer (a layer containing a polypropylene-based resin as a main component) as the release resin layer (B). By using a polypropylene-based resin layer as the release resin layer (B), good initial peel strength tends to be achieved.

[0059] Other resins and components may be added to the release resin layer (B) as appropriate within the scope of the present invention, but in order to achieve stable resealability between the release resin layer (B) and the adhesive resin layer (A), it is preferable to avoid mixing additives that tend to bleed onto the surface of the release resin layer (B) as much as possible. Examples of the other resins and components include low-crystalline or amorphous olefin resins, softeners, oils (mineral oils), stabilizers (antioxidants, etc.), liquid paraffin, etc. These may be used alone or in combination of two or more.

[0060] The release resin layer (B) is a single-layer resin layer, and its thickness is usually 1 to 1000 μm, preferably 10 to 500 μm, more preferably 20 to 300 μm or more, and even more preferably 3 to 200 μm. If the thickness of the release resin layer (B) is within the above range, the release resin layer (B) will not deform due to the heat-sealing pressure during heat-sealing and will tend to function satisfactorily as a release resin layer. Furthermore, even if a highly rigid resin such as a polyester resin is selected for the release resin layer (B), the layer will tend to easily break upon opening, and defects such as residual film will not easily occur.

[0061] <Resin layer (C)> The present multilayer film preferably has a resin layer (C) on the surface side of the adhesive resin layer (A) and / or the release resin layer (B). The resin layer (C) is a layer containing a thermoplastic resin, and preferably contains the thermoplastic resin as a main component. The resin layer (C) is not particularly limited as long as it has a layer configuration that results in an interlayer peel strength higher than that between the adhesive resin layer (A) and the release resin layer (B). The resin layer (C) may be a single layer or multiple layers.

[0062] The thermoplastic resin is preferably a thermoplastic resin that can be melt-extruded within a temperature range of 160 to 300°C.

[0063] Among these, from the viewpoints of moldability, transparency, and production costs, the thermoplastic resin is preferably at least one selected from the group consisting of polyolefin-based resins, polyamide-based resins, ethylene-vinyl alcohol-based copolymers, polyester-based resins, and polystyrene-based resins.

[0064] [Polyolefin resin] As the polyolefin-based resin, the polyolefin-based resins described above in connection with the release resin layer (B) can be used.

[0065] [Polyamide resin] As the polyamide-based resin, the polyamide-based resins described above in connection with the release resin layer (B) can be used.

[0066] [Ethylene vinyl alcohol copolymer] The ethylene vinyl alcohol copolymer (EVOH) is a resin obtained by saponifying a copolymer of ethylene and a vinyl ester monomer with an alkali catalyst or the like.

[0067] The content of ethylene structural units in the EVOH is not particularly limited, but from the viewpoint of film formation stability, it is usually 29 mol% or more, preferably 32 mol% or more, and from the viewpoint of gas barrier properties, it is usually 47 mol% or less, preferably 44 mol% or less. The saponification degree of EVOH is usually 90% or more, preferably 95% or more. By setting the content of ethylene structural units and the degree of saponification of EVOH within the above ranges, it tends to be possible to improve the gas barrier properties, mechanical strength, etc. These may be used alone or in combination of two or more.

[0068] It should be noted that the EVOH is not limited to those produced by saponification, as long as they have a similar chemical structure.

[0069] [Polyester Resin] As the polyester resin, the polyester resins described above in connection with the release resin layer (B) can be used.

[0070] [Polystyrene resin] Examples of the polystyrene resin include general-purpose polystyrene (GPPS), high-impact polystyrene (HIPS), styrene-(meth)acrylic acid ester copolymer, and resin containing 1 to 20 mass % of a rubber-like elastomer as dispersed particles in a continuous phase of a styrene copolymer consisting of a styrene-based monomer and a (meth)acrylic acid ester.

[0071] In particular, it is preferable to have an EVOH layer (a layer containing EVOH as the main component) and / or a polyamide-based resin layer (a layer containing a polyamide-based resin as the main component) in order to impart functions such as gas barrier properties and pinhole resistance to the present multilayer film.

[0072] In addition, the resin layer (C) may contain an adhesive resin so that the interlayer peel strength between the resin layer (C) and an adjacent layer is higher than the interlayer peel strength between the adhesive resin layer (A) and the release resin layer (B), or an adhesive resin layer may be disposed between the resin layer (C) and an adjacent layer to increase the interlayer peel strength between the resin layer (C) and the adjacent layer.

[0073] The adhesive resin can be the above-mentioned modified polyolefin resin, and among them, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, ethylene-maleic anhydride copolymer, and propylene-maleic anhydride copolymer are preferred in terms of excellent adhesiveness. Commercially available modified polyolefin resins that can be used as the adhesive resin include "Admer" manufactured by Mitsui Chemicals, Inc. and "Modic" manufactured by Mitsubishi Chemical Corporation.

[0074] The thickness (total) of the resin layer (C) is usually 1 to 1000 μm, preferably 10 to 600 μm, and more preferably 20 to 500 μm. When the thickness of the resin layer (A) is within the above range, it is easy to arrange a layer that imparts properties such as gas barrier property or pinhole resistance, or an adhesive resin layer, and also, during heat sealing, heat is easily transferred to the heat seal layer (D) described below, which tends to facilitate heat sealing with the sealed portion of the sealed object.

[0075] <Heat seal layer (D)> It is preferable from the viewpoint of heat sealing properties that the multilayer film has a heat seal layer (D) on the surface side of either the adhesive resin layer (A) or the release resin layer (B).

[0076] The heat seal layer (D) is not particularly limited as long as it has a layer structure that results in an interlayer peel strength higher than the interlayer peel strength between the adhesive resin layer (A) and the release resin layer (B), and may be a single layer or a multilayer.

[0077] The heat seal layer (D) contains a heat sealable thermoplastic resin, and preferably contains a thermoplastic resin as a main component.

[0078] The thermoplastic resin can be appropriately selected and used so as to provide an appropriate heat seal strength, taking into consideration the material of the sealing surface of the object to be sealed and the types of resins used in the adhesive resin layer (A), release resin layer (B), and resin layer (C) of the present multilayer film.

[0079] Specific examples of thermoplastic resins include the polyolefin resins, polystyrene resins, and polyester resins described above for the release resin layer (B), and the SIBS and styrene thermoplastic elastomers described above for the adhesive resin layer (A). These may be used alone or in combination of two or more. Among these, polyolefin resins are preferred because they are inexpensive, have excellent moldability, and can provide a higher interlayer peel strength than the interlayer peel strength between the adhesive resin layer (A) and the release resin layer (B) under heat sealing conditions (temperature: approximately 120 to 180°C) typically used for various multilayer films.

[0080] In addition, the heat seal layer (D) may contain an adhesive resin in the resin layer (C) so that the interlayer peel strength between the heat seal layer (D) and the adjacent layer is higher than the interlayer peel strength between the adhesive resin layer (A) and the release resin layer (B), or an adhesive resin layer may be disposed between the heat seal layer (D) and the adjacent layer to increase the interlayer peel strength between the heat seal layer (D) and the adjacent layer. As the adhesive resin, the adhesive resins explained in the resin layer (C) can be used.

[0081] It is preferable to add a lubricant or an anti-blocking agent to the heat seal layer (D) in order to improve processability during extrusion film formation and packaging suitability in a filling machine such as a deep drawing packaging machine.

[0082] Furthermore, other components may be appropriately added to the heat seal layer (D) within the scope of the present invention. Examples of the other components include antifogging agents, antistatic agents, heat stabilizers, nucleating agents, antioxidants, release agents, and ultraviolet absorbers. These may be used alone or in combination of two or more.

[0083] The thickness of the heat-sealable layer (D) is not particularly limited, but is usually 1 to 30 μm, preferably 3 to 25 μm, and more preferably 5 to 15 μm. If the thickness of the heat-sealable layer (D) is equal to or greater than the above-mentioned numerical value, problems such as deformation due to pressure from a heat-sealing hot plate during heat-sealing and deterioration of the functions of these layers tend to be prevented. On the other hand, if the thickness of the heat-sealable layer (D) is equal to or less than the above-mentioned numerical value, it tends to be possible to expose the adhesive resin layer (A) in a resealable state when peeling the adhesive resin layer (A) and the peelable resin layer (B) from each other.

[0084] Next, a method for producing the present multilayer film will be described. The method for producing the multilayer film in this embodiment is not particularly limited, but a co-extrusion method can be suitably used, which is excellent in terms of protecting the adhesive resin layer (A), productivity, hygiene, etc. For example, the various raw materials forming the adhesive resin layer (A), release resin layer (B), resin layer (C), and heat seal layer (D) described above can be heated and melted in separate extruders, laminated in the molten state by a known method such as a multi-manifold method or a feed block method, and then molded into the multilayer film by a T-die chill roll method, an inflation method, or the like.

[0085] The layer structure of the present multilayer film is not particularly limited as long as the adhesive resin layer (A) and the release resin layer (B) are directly laminated together, but the following layer structures are exemplified as preferred layer structures. (1) Resin layer (C) / Adhesive resin layer (A) / Peelable resin layer (B) / Heat seal layer (D) (2) Resin layer (C) / Peelable resin layer (B) / Adhesive resin layer (A) / Heat seal layer (D) (3) EVOH layer (C) / polyamide resin layer (C) ( / adhesive resin layer) / adhesive resin layer (A) / peelable resin layer (B) / heat seal layer (D) (4) Polyamide resin layer (C) / EVOH layer (C) ( / adhesive resin layer) / adhesive resin layer (A) / peelable resin layer (B) / heat seal layer (D) (5) EVOH layer (C) / polyamide resin layer (C) / peeling resin layer (B) / adhesive resin layer (A) ( / adhesive resin layer) / heat seal layer (D) (6) Polyamide resin layer (C) / EVOH layer (C) / peeling resin layer (B) / adhesive resin layer (A) ( / adhesive resin layer) / heat seal layer (D)

[0086] In order to improve the printability and lamination suitability of the present multilayer film, it is preferable to subject the surface of the outermost layer of the present multilayer film to a surface treatment. Examples of the surface treatment method include corona treatment, plasma treatment, chromic acid treatment, flame treatment, surface oxidation treatment such as hot air treatment, ozone or ultraviolet treatment, surface roughening treatment such as sandblasting, etc. Among these, corona treatment is preferred from the viewpoints of the effect of the surface treatment, productivity, and production costs.

[0087] Furthermore, a laminate substrate can be laminated on the outermost surface of the present multilayer film, if necessary, via an adhesive resin or adhesive, by a known method such as dry lamination or extrusion lamination, to form a laminate film or laminate sheet.

[0088] The laminate substrate is not particularly limited, and examples thereof include biaxially oriented polypropylene film, biaxially oriented nylon film, biaxially oriented polyethylene terephthalate film, unstretched polypropylene sheet, unstretched polyethylene terephthalate sheet, aluminum foil, paper, nonwoven fabric, etc. In the present invention, a dry lamination method is preferably used, and examples of adhesives used in this method include polyester-polyurethane adhesives, polyether-polyurethane adhesives, etc.

[0089] The multilayer film obtained in this manner is heat-sealed to an object to be sealed to form a multilayer body (packaging body), and when the multilayer film is then peeled off from the object to be sealed, delamination occurs between the adhesive resin layer (A) and the peelable resin layer (B), exposing the adhesive resin layer (A) in a resealable state, making it possible to reseal the film simply by applying pressure with hands or fingers.

[0090] For example, as shown in Figure 1, when the present multilayer film, which is composed of a resin layer (C) 3, an adhesive resin layer (A) 4, a release resin layer (B) 5, and a heat-seal layer (D) 6 in this order, is used as a lid material 1 and is heat-sealed to a base material 2, which is a sealed object and has a surface resin layer 7 and a heat-seal layer 8 laminated thereon, the heat-seal layer (D) 6 of the lid material 1 is heat-sealed to the heat-seal layer 8 of the base material 2, which is the sealed object. In other words, the lid material 1 and the base material 2 are bonded together at a heat-sealed portion 9 formed by heat sealing.

[0091] Thereafter, when the tab portion 10 provided on the lid material 1 is pinched and pulled, as shown in Figure 2, in the heat-sealed portion 9, first the release resin layer (B) 5 and the heat-seal layer (D) 6 on the tab portion 10 side are torn from the lid material 1, and peeling begins between the adhesive resin layer (A) 4 and the release resin layer (B) 5 in the lid material 1. When the peeling between the adhesive resin layer (A) 4 and the release resin layer (B) 5 reaches the heat-sealed portion 9 on the opposite side to the tab portion 10 side, the release resin layer (B) 5 and the heat-seal layer (D) 6 of the lid material 1 are torn. The torn release resin layer (B) 5 and the heat-seal layer (D) 6 of the lid material 1 move toward the base material 2, which is the sheet-receiving body, and exposed portions 11 of the adhesive resin layer (A) 4 and 12 of the release resin layer (B) 5 are formed.

[0092] When resealing, as shown in Figure 3, the peeled lid material 1 is placed over the base material 2, and the resin layer (C) 3 is pressed and bonded with hands or fingers, so that the exposed portion 11 of the adhesive resin layer (A) 4 of the lid material 1 overlaps with the exposed portion 12 of the peeled resin layer (B) 5 of the lid material 1 that has transferred to the base material 2, thereby resealing the lid material 1 and the base material 2.

[0093] Furthermore, although not shown, when the heat seal layer (D) 6 of the lid material 1, which is composed of a resin layer (C) 3, a peelable resin layer (B) 5, an adhesive resin layer (A) 4, and a heat seal layer (D) 6 in this order, is heat sealed to the heat seal layer 8 of the base material 2, when the tab portion 10 provided on the lid material 1 is pinched and pulled, the adhesive resin layer (A) 4 and the heat seal layer (D) 6 on the tab portion 10 side are first broken from the lid material 1 in the heat seal portion 9, and peeling begins between the adhesive resin layer (A) 4 and the peelable resin layer (B) 5 in the lid material 1. When the peeling between the adhesive resin layer (A) 4 and the peelable resin layer (B) 5 reaches the heat seal portion 9 opposite the tab portion 10 side, the adhesive resin layer (A) 4 and the heat seal layer (D) 6 of the lid material 1 are broken. The adhesive resin layer (A) 4 and heat seal layer (D) 6 of the ruptured lid material 1 move to the base material 2, which is the sheet-receiving body, forming exposed portions of the adhesive resin layer (A) 4 and the peelable resin layer (B) 5, making the package resealable.

[0094] In order to realize such a resealable function, it is necessary to have a layer structure in which the interlayer peel strength between the adhesive resin layer (A) and the release resin layer (B) is lower than the interlayer peel strength of the other layers. At the same time, it is also important to ensure that the interlayer peel strength is sufficient to maintain the functionality of the package so that the layers do not easily peel or are not opened by a slight impact, etc.

[0095] When the multilayer film is heat-sealed to a support and then peeled at 23°C, the lower limit of the peel strength (initial peel strength) is typically 100 gf / 15 mm width, preferably 300 gf / 15 mm width, and more preferably 1000 gf / 15 mm width. On the other hand, the upper limit of the peel strength (initial peel strength) is not particularly limited, but is equal to or lower than the interlayer peel strength between the adhesive resin layer (A) and the release resin layer (B), and is preferably 5000 gf / 15 mm width, more preferably 4000 gf / 15 mm width, and even more preferably 3500 gf / 15 mm width. If the peel strength (initial peel strength) is equal to or higher than the lower limit, problems such as the package being easily opened by slight impact are unlikely to occur. If it is equal to or lower than the upper limit, the package tends to be easily opened by hand (easy opening).

[0096] Regarding resealability after opening, the lower limit of the interlayer peel strength (resealing peel strength) when peeled at 23°C is usually 20 gf / 15 mm width, preferably 30 gf / 15 mm width, and more preferably 50 gf / 15 mm width. The upper limit of the resealing peel strength is not particularly limited, but is equal to or less than the peel strength (initial peel strength), preferably 1000 gf / 15 mm width, and more preferably 800 gf / 15 mm width. If the resealing peel strength is within the above range, practical resealability tends to be obtained.

[0097] The present multilayer film can be suitably used as a lid material for various packages. For example, when the present multilayer film is used as a lid material for a package (container), the heat seal layer (D) of the present multilayer film and the heat seal layer of the base material (sealed object) are overlapped and heat sealed to form a package (container) that has airtightness, practical initial peel strength, and a resealable function.

[0098] As mentioned above, the present multilayer film can be used as a lid material for various containers, and its use is not particularly limited, but it can be used, for example, as a container for packaging several items such as instant noodles, snacks, chocolate confectionery, processed meat products such as sliced ​​ham, wet tissues, sweat blotting paper, air fresheners, disposable diapers, etc., or as a container for packaging cosmetics that are opened and used each time, sanitary products, medicinal patches, first-aid adhesive bandages, throat lozenges, etc. In particular, it can be suitably used as a lid material for packages for storing items in which the remaining contents after opening are susceptible to deterioration due to oxidation, moisture absorption, drying, etc. [Example]

[0099] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples as long as it does not depart from the gist of the invention. In the examples, "parts" and "%" are by mass.

[0100] Prior to the examples, the following raw materials were prepared. [Styrene-isobutylene-styrene copolymer] SIBS1 (styrene-isobutylene-styrene copolymer, styrene content 23%, glass transition temperature -65°C, MFR (230°C) 6g / 10min) SIBS2 (styrene-isobutylene-styrene copolymer, styrene content 24%, glass transition temperature -65°C, MFR (230°C) 20g / 10min) [Thermoplastic elastomer] TPO (polyethylene-butene copolymer, density 0.864 g / cm 3 , melting point 38℃, SEBS1 (styrene-based thermoplastic elastomer, styrene content 12%, glass transition temperature -42°C) SEPS1 (styrene-based thermoplastic elastomer, styrene content 20%, glass transition temperature -17°C) [Tackifier] Tackifier 1 (aromatic modified terpene, softening temperature 125°C) Tackifier 2 (hydrogenated rosin ester, softening temperature 96°C) Tackifier 3 (hydrogenated rosin ester, softening temperature 85°C) [Polyolefin resin] hPP (homopolypropylene, melting point 163°C) AD1 (modified polyethylene resin, MFR (230°C) 4.1g / 10min, melting point 122°C) AD2 (modified polyethylene resin, MFR (230°C) 9.5g / 10min, melting point 123°C) [Polyester Resin] PET (oriented polyethylene terephthalate) [Anti-blocking agent] AB agent (polyethylene resin base, anti-blocking agent masterbatch) [Other materials] PE / ONy laminate film: A laminate film with a total thickness of 75 μm, made by bonding unstretched polyethylene film (Mitsui Chemicals Tohcello's "TUX" 60 μm) and biaxially oriented polypropylene film (Unitika Ltd.'s "Emblem" 15 μm) using the dry lamination method. hPP sheet: 100 μm thick non-oriented polypropylene (CPP) sheet Stretched PET film: 50 μm thick biaxially stretched polyethylene terephthalate (PET) sheet

[0101] <Examples 1 to 7, Comparative Examples 1 and 2> The raw materials for the adhesive resin layer (A) shown in Table 1 below were kneaded in a Labo Plastomill ("4C150" manufactured by Toyo Seiki Co., Ltd.) at 200°C x 60 rpm x 5 minutes, and then press-molded at 200°C to obtain an adhesive resin layer (A) with a thickness of 50 μm. The obtained adhesive resin layer (A) was stacked in the order of resin layer (C) / adhesive resin layer (A) / release resin layer (B) / [hPP sheet] using the raw materials for the release resin layer (B) and resin layer (C) shown in Table 1 below, and press-molded at 200°C to produce a four-layer multilayer film. The resin layer (C) side of each obtained multilayer film was heat-sealed to the PE side of a PE / ONy laminate film as the sealed object under conditions of 160°C x 3 seconds, pressure 500N, seal width 2mm x 100mm, to prepare samples (multilayer bodies) for peel tests.

[0102] Example 8 The raw materials for the adhesive resin layer (A) shown in Table 1 below were kneaded in a Labo Plastomill ("4C150" manufactured by Toyo Seiki Co., Ltd.) at 200°C x 60 rpm x 5 minutes, and then press-molded at 200°C to obtain an adhesive resin layer (A) with a thickness of 50 μm. The obtained adhesive resin layer (A) was stacked in the order of resin layer (C) / adhesive resin layer (B) / release resin layer (B) / [stretched PET film] using the raw materials for the release resin layer (B) and resin layer (C) shown in Table 1 below, and press-molded at 200°C to produce a four-layer multilayer film. The resin layer (C) side of the obtained multilayer film was heat-sealed to the PE side of a PE / ONy laminate film as the object to be sealed under the conditions of 200°C x 3 seconds, pressure 500N, seal width 2mm x 100mm, to prepare a sample (multilayer body) for peel testing.

[0103] <Examples 9 to 11, Comparative Example 3> The raw materials for the adhesive resin layer (A), release resin layer (B), and resin layer (C) shown in Table 1 below were each melt-extruded using a single-screw extruder, co-extruded using the T-die method at a die temperature of 240°C, and then cast using a cast roll at 90°C to produce a multilayer film. The PE side of a PE / ONy laminate film was heat-sealed to the resin layer (C) side of the obtained multilayer film under conditions of 160°C x 3 seconds, pressure 500N, seal width 2mm x 100mm, and an [hPP sheet] was placed on top of the peelable resin layer (C) side of the multilayer film and heat-sealed under conditions of 200°C x 3 seconds, pressure 500N, seal width 2mm x 100mm to prepare a sample (multilayer body) for peel tests.

[0104] [Glass transition temperature (Tg) of adhesive resin layer (A)] The raw materials for the adhesive resin layer (A) of Examples 8 to 11 and Comparative Example 3 shown in Table 1 below were kneaded in a Laboplastomill (Toyo Seiki Co., Ltd., "4C150") at 200°C x 60 rpm x 5 minutes, and then press-molded at 200°C to obtain a single-layer adhesive resin layer (A). The glass transition temperatures (Tg) of the adhesive resin layers (A) obtained in Examples 8 to 11 and Comparative Example 3, and the adhesive resin layers (A) prepared above in Examples 1 to 7 and Comparative Examples 1 and 2 were measured using a differential scanning calorimeter (TA Instruments, "DSC2500") at a temperature of -120°C to 200°C (10°C / min). The results are shown in Table 1 below.

[0105] The obtained sample (multilayer body) was subjected to the following evaluations, and the results are shown in Table 1 below.

[0106] [Peel test] The obtained sample (multilayer body) was cut into a strip with a width of 15 mm and peeled at room temperature at a peeling rate of 200 mm / min to measure the initial peel strength and evaluate it according to the following evaluation criteria. The peeled surface was also visually confirmed. Thereafter, the peeled surfaces of the measured samples were resealed by pressing together, and the peel test was conducted again to measure the resealing strength, which was evaluated according to the following evaluation criteria. [Initial strength] ◎: 1000gf / 15mm width or more 〇: 300gf / 15mm width or more, less than 1000gf / 15mm width ×: Less than 300gf / 15mm width or no peeling [Resealing strength] 〇: 50gf / 15mm width or more ×: Less than 50gf / 15mm width

[0107] 〔comprehensive evaluation〕 Based on the evaluation results of the peel test, a comprehensive evaluation was made according to the following criteria. [Evaluation criteria] 〇: Initial strength and resealing strength are all rated "〇" or above ×: Initial strength and resealing strength are evaluated as "×".

[0108] [Table 1]

[0109] The results in Table 1 show that the multilayer films of Examples 1 to 11 had good initial strength, and when peeled, interlayer delamination occurred between the adhesive resin layer (A) and the peelable resin layer (B), exposing the adhesive resin layer (A), thereby exhibiting good resealing strength. On the other hand, the multilayer films of Comparative Examples 1 and 2, which did not contain SIBS in the adhesive resin layer (B), had too high initial strength and could not be opened. Similarly, the multilayer film of Comparative Example 3, which did not contain SIBS in the adhesive resin layer (B), experienced interlayer delamination between the adhesive resin layer (A) and the resin layer (C) when peeled, preventing exposure of the adhesive resin layer (A), and thus failing to achieve resealability. [Industrial Applicability]

[0110] The multilayer film can be suitably used as a lid material for resealable packages. [Explanation of symbols]

[0111] 1 Lid material 2 Bottom material 3. Resin layer of lid material 4. Adhesive resin layer of lid material 5. Lid peeling resin layer 6 Heat seal layer of lid material 7. Surface resin layer of base material 8 Heat-seal layer of base material 9 Heat-sealed part of base material 10 Tab of lid 11 Exposed portion of adhesive resin layer when peeled off 12 Exposed portion of heat seal layer when peeled

Claims

1. A resealable multilayer film in which an adhesive resin layer (A) and a release resin layer (B) are directly laminated together, wherein the adhesive resin layer (A) contains a styrene-isobutylene-styrene copolymer.

2. 2. The resealable multilayer film according to claim 1, wherein the styrene-isobutylene-styrene copolymer has a glass transition temperature of −35° C. or lower.

3. The resealable multilayer film according to claim 1 , wherein the release resin layer (B) comprises a polypropylene-based resin.

4. 2. The resealable multilayer film according to claim 1, further comprising a resin layer (C), wherein the resin layer (C) contains at least one thermoplastic resin selected from the group consisting of polyolefin resins, polyamide resins, ethylene-vinyl alcohol copolymers, polyester resins, and polystyrene resins.

5. 5. The resealable multilayer film according to claim 4, wherein the resin layer (C) comprises an ethylene-vinyl alcohol copolymer layer and / or a polyamide resin layer.

6. The resealable multilayer film according to claim 5 , further comprising a heat seal layer (D) on the surface side of either the adhesive resin layer (A) or the release resin layer (B).

7. 2. The multilayer film with resealable function described in claim 1, wherein, when the resealable multilayer film and an object to be sealed are heat-sealed and the resealable multilayer film is peeled off from the object to be sealed, interlayer delamination occurs between the adhesive resin layer (A) and the peelable resin layer (B), exposing the adhesive resin layer (A), thereby making the adhesive resin layer (A) and the peelable resin layer (B) resealable.

8. A resealable multilayer body obtained by heat-sealing the resealable multilayer film according to any one of claims 1 to 7 to an article to be sealed.

9. 9. The resealable multilayer body according to claim 8, wherein, when the resealable multilayer film is peeled from the resealable multilayer body, the adhesive resin layer (A) or the peelable resin layer (B) of the resealable multilayer film breaks and interlayer delamination occurs between the adhesive resin layer (A) and the peelable resin layer (B).

10. A resealable package using the resealable multilayer body according to claim 8.

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