Heat-sealable laminated film

Abstract

To provide a heat-fusible laminated film having high adhesion force at a laminated interface and a good bonding condition when heat fused and to provide a roll on which the same is wound.SOLUTION: There is provided a heat-fusible laminated film which comprises a layer B, a layer C, a layer A, the layer C and the layer B in this order in which at least the layer C, the layer A and the layer C are laminated by co-extrusion, wherein the layer A contains 100 to 70 mass% of a polymer A1 having 90 mol% or more and 100 mol% or less of a constitutional unit derived from 4-methyl-1-pentene based on the total constitutional unit, the layer B contains 100 to 70 mass% of a heat-fusible polyolefin B1 and the layer C contains 50 mass% or more of a copolymer C1 having 60 mol% or more and 99 mol% or less of a constitutional unit derived from 4-methyl-1-pentene and 1 mol% or more and 40 mol% or less of a constitutional unit derived from an α-olefin having 2 or more and 20 or less carbon atoms other than 4-methyl-1-pentene.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a heat-sealable laminated film in which a heat-sealable layer (hereinafter sometimes referred to as "layer B") is provided on both sides of a base layer (hereinafter sometimes referred to as "layer A") via an easy-adhesion layer (hereinafter sometimes referred to as "layer C"), and to a roll of the same wound up. [Background technology]

[0002] Films and sheets having heat-sealing properties are laminates in which a heat-sealing layer is provided on the outermost surface of at least one side of a substrate, and are used in a variety of applications for the purposes of packaging, reinforcement, etc., by laminating the heat-sealing layer to an adherend made of resin or metal. The substrate is selected depending on the purpose, but resin substrates are often used, and an appropriate resin is selected depending on the desired properties.

[0003] In order to obtain excellent adhesion to the adherend, not only is there required adhesion between the adherend and the heat-sealable layer, but there is also required high adhesion between the substrate and the heat-sealable layer. This is because the area with the weakest adhesion will be destroyed or peeled off when subjected to external stress that pulls the entire layer apart. be. As an example of such a heat-sealable laminate film, Patent Document 1 discloses a laminate film for tab leads, which has a heat-sealable resin layer (A) containing a modified polypropylene-based resin or the like and a similar heat-sealable resin layer (B) between which a heat-resistant resin layer (C) is provided, and the heat-resistant resin layer (C) contains a copolymer of 4-methyl-1-pentene and an α-olefin and an α-olefin-based resin (1) having a melting point of 30°C to 110°C.

[0004] However, in order to ensure the adhesion between the heat-resistant resin layer (C) as the base material and the heat-sealable resin layer, it was necessary to make the copolymer contained in the heat-resistant resin layer (C) contain a certain amount of α-olefin or a certain amount of α-olefin resin (1).As a result, the heat resistance and mechanical properties of the base material layer were not sufficient when heat-sealing was performed.

[0005] On the other hand, a technique using a substrate layer with improved heat resistance is also known, and a technique exists in which an easy-adhesion layer (also called an "intermediate layer") is provided between the substrate layer and the heat-sealable layer to improve the adhesion between the two layers. For example, Patent Document 2 proposes a heat-sealable laminated film in which an easy-adhesion layer containing a resin obtained by modifying a copolymer of propylene and 1-butene with maleic acid is provided between a heat-sealable layer containing an acid-modified polyolefin or the like and a substrate layer containing a methylpentene polymer or the like.

[0006] On the other hand, although not related to heat-sealable laminated films, Patent Document 3 discloses a technique for bonding a thermoplastic resin layer (X) and a thermoplastic resin layer (Y) using an adhesive resin composition containing a propylene polymer (A), an ethylene polymer (B), and a thermoplastic resin (C) including a copolymer containing 60 mol % to 99 mol % of structural units derived from 4-methyl-1-pentene and 1 mol % to 40 mol % of structural units derived from an α-olefin having from 2 to 20 carbon atoms other than 4-methyl-1-pentene, wherein the contents of component (A) are 45 to 75 parts by mass, component (B) are 5 to 20 parts by mass, and component (C) are 15 to 45 parts by mass, per 100 parts by mass of the total. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 6484081 [Patent Document 2] Patent No. 6621262 [Patent Document 3] Japanese Patent Publication No. 2020-111731 Summary of the Invention [Problem to be solved by the invention]

[0008] However, according to the investigations of the present inventors, it was found that in the invention of Patent Document 2, the adhesive layer is formed by coating in a solution state on the film that serves as the base layer, and then the heat-sealable layer is formed by melt flow, which tends to result in insufficient adhesion between the layers. In particular, when the base layer is a methylpentene polymer, it was found that the adhesive layer made of a resin obtained by modifying a copolymer of propylene and 1-butene with maleic acid results in insufficient adhesion between the two layers.

[0009] Furthermore, the invention of Patent Document 3 was not primarily intended for use in a heat-sealable laminate film, and the adhesive strength required between each layer is low, so the adhesive resin composition disclosed therein does not have sufficient adhesive strength for a heat-sealable laminate film.

[0010] Therefore, an object of the present invention is to provide a heat-sealable laminated film that has high adhesion at the lamination interface and provides a good bonded state when heat-sealed, and a roll of the same. [Means for solving the problem]

[0011] As a result of intensive research conducted by the inventors to solve the above-mentioned problems, they discovered that the above-mentioned problems can be solved by co-extruding a base layer containing a polymethylpentene resin and an easy-adhesion layer (preferably a heat-sealable layer) containing a copolymer of 4-methyl-1-pentene and another α-olefin, and thus completed the present invention.

[0012] That is, the present invention includes the following:

[0013] [1] A heat-sealable laminated film comprising a B layer, a C layer, an A layer, a C layer, and a B layer in this order, wherein at least the C layer, the A layer, and the C layer are laminated by coextrusion, the layer A contains 100 to 70 mass % of a polymer A1 having 90 mol % or more and 100 mol % or less of structural units derived from 4-methyl-1-pentene based on all structural units, The layer B contains 100 to 70 mass % of a heat-fusible polyolefin B1, The layer C is a heat-sealable laminated film containing 50 mass% or more of a copolymer C1 having 60 mol% or more and 99 mol% or less of structural units derived from 4-methyl-1-pentene and 1 mol% or more and 40 mol% or less of structural units derived from an α-olefin having 2 to 20 carbon atoms other than 4-methyl-1-pentene.

[0014] [2] The melting peak temperature (if there are multiple melting peak temperatures, the median between the lowest and highest values) measured by DSC for the heat-fusible polyolefin B1 is taken as the melting point T mB1 When T mB1 The heat-sealable laminate film according to [1], wherein the thickness deformation rate of the layer A is 5% or less when a load of 3 MPa is applied at a temperature of +30°C for 10 minutes.

[0015] [3] The heat-sealable laminate film according to [1] or [2], wherein the polymer A1 contains 100 mol % of structural units derived from 4-methyl-1-pentene based on all structural units.

[0016] [4] The heat-bondable laminate film according to any one of [1] to [3], wherein the layer A contains 100% by mass of the polymer A1.

[0017] [5] The method according to any one of [1] to [4], wherein when the thickness of the A layer is tA, the thickness of the B layer is tB, and the thickness of the C layer is tC, the following formulas (1) and (2) are satisfied: Heat-sealable laminated film . 2≦tA / tB≦5 (1) 1≦tB / tC≦100 (2)

[0018] [6] The heat-sealable laminate film according to any one of [1] to [5], wherein the heat-sealable polyolefin B1 is a polyolefin containing a modified product obtained by modification with an acid anhydride, the acid anhydride content being 0.1 to 3 mass %, and the amount of low-molecular-weight components having a number average molecular weight of 1,000 or less extracted with acetone being less than 1 mass %.

[0019] [7] A roll in which the heat-sealable laminate film according to any one of [1] to [6] is wound in the longitudinal direction. [Effects of the Invention]

[0020] According to the present invention, it is possible to provide a heat-sealable laminated film that has high adhesion at the lamination interface and provides a good bonded state when heat-sealed, and a roll of the same.

[0021] The details of the reason for this are unknown, but it is thought to be as follows: Once Layer A, which is mainly composed of Polymer A1, whose main component is structural units derived from 4-methyl-1-pentene, solidifies into a film, it tends to have a high degree of crystallinity, which makes it difficult to sufficiently wet the heat-fusible resin layer, which has low surface energy, and to diffuse the heat-fusible Layer B into Layer A, resulting in poor adhesion.

[0022] However, if Layer A is in a molten state, it is possible to achieve adhesion by mutual diffusion of the components of Layer C, which is made of a material with high affinity for Layer A and Layer B. Therefore, by co-extruding at least Layer A and Layer C and laminating them in a molten state, high adhesion can be achieved between the layers. Furthermore, the heat-sealable Layer B exhibits good adhesion when bonded to metals, etc., thereby improving durability both initially and in humid and hot environments. Furthermore, because the polymer A1 contains a small amount of copolymerization components, it can increase its crystallinity, thereby improving mechanical properties even in an unstretched form. When heat-sealing the heat-sealable Layer B, the thickness deformation rate of Layer A can be reduced, and since it is not stretched, the thermal deformation rate in the in-plane direction can also be reduced. As a result, the bonded state is good when heat-sealed. DETAILED DESCRIPTION OF THE INVENTION

[0023] The present invention will be described in detail below. For convenience of explanation, the film formation direction of a film may be referred to as the machine axis direction, longitudinal direction, longitudinal direction, or MD direction, and the direction perpendicular to the film formation direction and thickness direction may be referred to as the width direction, transverse direction, or TD direction. Furthermore, various physical properties described in this specification are specifically measured by the methods described in the Examples.

[0024] [Heat-sealable laminated film] The heat-sealable laminate film of the present invention is a heat-sealable laminate film comprising a B layer, a C layer, an A layer, a C layer, and a B layer in this order, with at least the C layer, the A layer, and the C layer laminated by coextrusion. That is, this heat-sealable laminate film may comprise an A layer as a base layer, a C layer as an easy-adhesion layer, and a B layer as a heat-sealable layer, in the order of the B layer, the C layer, the A layer, the C layer, and the B layer.

[0025] For this reason, other layers may be included. For example, a protective film, a release film, a cover film, etc. may be provided on the surface side of Layer B, or an adherend may be provided by thermally bonding it to one side in advance. Furthermore, an intermediate layer or an easy-adhesion layer having a different composition from Layer C may be included between Layer B and Layer C. Also, a layer structure in which Layer C and Layer A are repeatedly included is possible, such as a heat-sealable laminate film including Layer B, Layer C, Layer A, Layer C, Layer A, Layer C, and Layer B.

[0026] Furthermore, it is sufficient if at least the C layer, the A layer, and the C layer are directly laminated by co-extrusion, but it is preferable that the B layer, the C layer, the A layer, the C layer, and the B layer are directly laminated by co-extrusion, from the viewpoint of increasing the adhesion between each layer while simplifying the manufacturing process.

[0027] In the present invention, the specification of "laminated by coextrusion" specifies the structure of an object based on the manufacturing method. However, there are circumstances in which it is impossible or impractical to directly specify the object based on its structure or properties, as follows:

[0028] When a three-layer laminate film is produced by coextrusion, the adhesion at the laminate interface differs from that of a film produced by thermally laminating the other two layers onto a previously produced base film, and it is clear that there are microstructural differences. In other words, when looking at the molecular microstructure at the laminate interface, the differences in the state of mutual diffusion and penetration of the components of each layer are thought to be the cause of the differences in adhesion. However, because the difference in diffusion state is merely a matter of degree, it is difficult to structurally identify such differences.

[0029] Therefore, no wording can be found that identifies the structure or characteristics that differ from the prior art, and it is impossible or impractical to analyze and identify such structure or characteristics based on measurements. Therefore, with regard to the present invention, at the time of filing, there exists a situation in which it is impossible or almost impractical to directly identify the product by its structure or characteristics.

[0030] Hereinafter, each component of the heat-sealable laminate film of the present invention will be described.

[0031] [A layer (base material layer)] The thermoplastic resin contained in the resin composition constituting Layer A, which is the base layer, can be selected depending on the characteristics required of the base layer for the intended use, but in order to ensure the durability of the base layer itself in a harsh humid and hot environment, it is preferable that the thermoplastic resin does not have functional groups that can become reaction points for water molecules, and that it has a high melting point so that it can withstand the heat during lamination and the heat caused by the environment.

[0032] From this perspective, in the present invention, the resin composition constituting the layer A contains, as a main component, a polymer A1 having 90 mol % to 100 mol % of structural units derived from 4-methyl-1-pentene relative to all structural units.

[0033] The polymer A1 may be contained in Layer A in an amount of 100 to 70% by mass, but from the viewpoint of reducing the thickness deformation rate and in-plane thermal deformation rate of Layer A, the polymer A1 is preferably contained in Layer A in an amount of 100 to 80% by mass, more preferably 100 to 90% by mass, and most preferably 100% by mass. Within this content range, the 4-methyl-1-pentene polymer is likely to have an improved heat resistance, and a hard film is likely to be obtained by taking advantage of the fast crystallization rate.

[0034] Layer A may contain 0 to 30% by mass of other resin A2, but for the same reasons, it is preferable that layer A contains 0 to 20% by mass of resin A2, more preferably 0 to 10% by mass, and most preferably does not contain other resin A2.

[0035] When the melting point of the base layer is TmS and the melting point of the resin constituting the heat-sealable layer (described later) is TmHS, the difference between them is defined as ΔT (=TmS-TmHS). The combination is preferably such that ΔT is in the range of 0 to 120°C, more preferably 10 to 100°C. By setting ΔT to 0°C or higher, it is possible to prevent the base layer from melting first due to the heat applied during lamination, for example. Furthermore, by setting ΔT to 120°C or lower, the difference in melt viscosity does not become too large when melting and laminating in the thickness direction in an extruder, preventing the occurrence of uneven lamination and enabling stable production. From this viewpoint, ΔT is more preferably 20°C to 90°C, and particularly preferably 40°C to 80°C. Regarding the melting point TmS, the melting point TmS of polymer A1, which is the main component of layer A, is used. mA1 It is also possible to consider it as such.

[0036] The thickness of Layer A may be 20 μm or more, preferably 25 μm or more, more preferably 35 μm or more, and even more preferably 45 μm or more, in order to obtain the strength required as a base layer for providing a heat-sealable layer, and is preferably 300 μm or less, more preferably 270 μm or less, and even more preferably 250 μm or less, or alternatively may be 150 μm or less or 130 μm or less.

[0037] [Polymer A1] Polymer A1 contains 90 mol % or more and 100 mol % or less of structural units derived from 4-methyl-1-pentene, preferably 92 mol % or more and 100 mol % or less, and more preferably 95 mol % or more and 100 mol % or less, of all structural units.

[0038] Polymer A1 may further contain structural units derived from an α-olefin other than 4-methyl-1-pentene in an amount of 0 mol % or more and 10 mol % or less, preferably 0 mol % or more and 8 mol % or less, and more preferably 0 mol % or more and 5 mol % or less, based on all structural units.

[0039] That is, examples of polymer A1 include homopolymers polymerized using 4-methyl-1-pentene as a monomer, as well as copolymers copolymerized with 90 mol % or more of 4-methyl-1-pentene as a monomer and 10 mol % or less of an α-olefin other than 4-methyl-1-pentene as a monomer.

[0040] When the polymer A1 is a copolymer, the copolymerized monomers are is the number of carbon atoms The α-olefin is preferably from 2 to 20. Examples of the α-olefin to be copolymerized include one or more of ethylene, propylene, 1-butene, 1-hexene, 1-octene, 1-decene, 1-tetradecene, 1-octadecene, and the like.

[0041] Melting point T of polymer A1 mA1 The melting point is preferably 230°C or higher. When a 4-methyl-1-pentene copolymer having a high copolymerization ratio of other monomers is used, the melting point decreases, but in this case, the crystallization speed decreases and the rigidity as a base layer decreases, so that the thickness deformation rate of the A layer increases when the metal is bonded above the melting point of the heat-sealable layer described below. From this viewpoint, T mA1 The melting point T is preferably 231° C. or higher, more preferably 232° C. or higher, and even more preferably 233° C. or higher. There is no upper limit to the melting point T. mA1 The temperature is preferably 250°C or lower, and more preferably 245°C or lower.

[0042] In the case of a base layer using polymer A1, TmS is improved compared to general polypropylene, making it easier to ensure ΔT, but because of its low surface energy and fast crystallization rate, it has low affinity with the heat-sealable layer, making it difficult to increase adhesion. Therefore, it is particularly effective to provide layer C, which is an easy-adhesion layer, by coextrusion.

[0043] [Other Resins A2] Layer A can contain a resin A2 other than polymer A1. The other resin A2 may be any resin as long as it has adequate compatibility and dispersibility with polymer A1, and examples thereof include polyolefins (including modified polyolefins), 4-methyl-1-pentene copolymers, and copolymers of 4-methyl-1-pentene and α-olefins, with polyolefins being preferred. Polyolefins are advantageous in that they do not have functional groups that can serve as reaction sites for water molecules, and the use of polyolefins improves dispersibility in polymer A1.

[0044] Examples of polyolefin resins include the following polyolefin resins and modified polyolefin resins: In this specification, the term "modified" refers to a resin containing a structural unit different from the structural unit of polyolefin or the like in the same molecule.

[0045] Examples of polyolefin resins include polyolefin resins such as high-density polyethylene, low-density polyethylene, ultra-high molecular weight polyethylene, linear low-density polyethylene, polypropylene, and poly(1-butene). Blends of these polyolefin resins and copolymers containing these as constituent components are also included. Among these polyolefin resins, polypropylene is particularly preferred.

[0046] In particular, when mixing with a 4-methyl-1-pentene polymer (polymer A1) by melt kneading, a similar polyolefin resin or a modified polyolefin resin can be used, but from the viewpoint of compatibility, it is preferable to use a polypropylene resin copolymerized with 4-methyl-1-pentene or a maleic acid-modified polypropylene resin. The modification method can be graft modification or copolymerization.

[0047] Specific modified polyolefin resins include, for example, maleic anhydride-modified polyethylene, maleic anhydride-modified polypropylene, ethylene / acrylic acid copolymer, ethylene / methacrylic acid copolymer, and copolymers in which a part or all of the carboxylic acid moieties in these copolymers have been converted into salts with sodium, lithium, potassium, zinc, or calcium, ethylene / methyl acrylate copolymer, ethylene / ethyl acrylate copolymer, ethylene / methyl methacrylate copolymer, ethylene / ethyl methacrylate copolymer, and ethylene / ethyl acrylate-g-maleic anhydride copolymer (where "-g-" represents graft (hereinafter referred to as "ethyl acrylate-g-maleic anhydride copolymer"). (same), ethylene / methyl methacrylate-g-maleic anhydride copolymer, ethylene / propylene-g-maleic anhydride copolymer, ethylene / butene-1-g-maleic anhydride copolymer, ethylene / propylene / 1,4-hexadiene-g-maleic anhydride copolymer, ethylene / propylene / dicyclopentadiene-g-maleic anhydride copolymer, ethylene / propylene / 2,5-norbornadiene-g-maleic anhydride copolymer, hydrogenated styrene / butadiene / styrene-g-maleic anhydride copolymer, hydrogenated styrene / isoprene / styrene-g-maleic anhydride copolymer, etc. Among these, maleic acid-modified polypropylene or ethylene-propylene copolymer, etc. are particularly preferred.

[0048] [Other optional ingredients in Layer A] Layer A may contain an appropriate filler as needed to improve slippage, as long as it does not impair the objectives of the present invention. Examples of fillers that can be used include those conventionally known as slippage-imparting agents for films and sheets, such as calcium carbonate, calcium oxide, aluminum oxide, kaolin, silicon oxide, zinc oxide, carbon black, silicon carbide, tin oxide, crosslinked acrylic resin particles, crosslinked polystyrene resin particles, melamine resin particles, and crosslinked silicone resin particles. Furthermore, layer A may also contain colorants, antistatic agents, antioxidants, organic lubricants, catalysts, and the like, as appropriate. In particular, when considering use in a humid and hot environment, additives with low elution are preferably used.

[0049] Other optional components include various additives that have been conventionally used in 4-methyl-1-pentene polymers, etc. Examples of such additives include stabilizers, impact modifiers, flame retardants, mold release agents, sliding modifiers, colorants, plasticizers, and crystal nucleating agents.

[0050] Such other optional components can be used in layer A in an amount of, for example, 0.001 to 10% by mass.

[0051] [B layer (thermal adhesive layer)] Layer B, which is a heat-sealable layer, contains 100 to 70 mass % of heat-sealable polyolefin B1, and from the viewpoints of wet heat durability and adhesive strength to an adherend, it contains preferably 100 to 75 mass %, more preferably 100 to 80 mass %, still more preferably 100 to 90 mass %, and most preferably 100 mass % of heat-sealable polyolefin B1. In this specification, "heat-sealable" refers to the property of being able to be fused to an adherend by heating, preferably the property of being able to be fused to a metal such as SUS316 by heating.

[0052] The layers B provided on both sides of the layer A may have the same or different compositions, but when, for example, adherends made of the same material are to be thermally bonded, it is preferable to provide heat-sealable layers of the same composition on both sides. The thicknesses of the heat-sealable layers may be the same or different, but in such cases, it is preferable to provide heat-sealable layers of the same thickness on both outermost surfaces.

[0053] The thickness of Layer B is preferably 100 μm or less. Regarding the adhesion between the heat-sealable layer provided by coextrusion and the easy-adhesion layer and base layer described later, strong adhesion can be obtained. However, when using, for example, an acid-modified polyolefin resin, the acid-modified portion has functional groups that are affected by moisture, so if the layer is made unnecessarily thick, the heat-sealable layer tends to become brittle and break in a severe humid and hot environment. From this perspective, the thickness of Layer B is preferably 90 μm or less, more preferably 80 μm or less, even more preferably 75 μm or less, and particularly preferably 60 μm or less. Furthermore, if the thickness is too thin, the mechanical relaxation function in the thickness direction of the heat-sealable layer is weakened, so it is preferably 10 μm or more, more preferably 15μm or more , and particularly preferably 20 μm or more.

[0054] The layer B is preferably provided on both sides of the base layer via an easy-adhesion layer by co-extrusion, which allows the state of the lamination interface on both sides of the base layer to be the same on both sides, which is more preferable in terms of improving the adhesion of the lamination interface on both sides.

[0055] [Heat-bondable polyolefin B1] As the heat-fusible polyolefin B1, an unmodified polyolefin resin can be used, but modified polyolefins are preferred, and modified polyolefins containing polypropylene are particularly preferred.

[0056] Examples of unmodified polyolefin resins include homopolymers and copolymers of olefins having 2 to 8 carbon atoms, and copolymers of olefins having 2 to 8 carbon atoms with other monomers. Specific examples include polyethylenes such as high-density polyethylene (HDPE), low-density polyethylene (LDPE), and linear low-density polyethylene resins, polypropylene, polyisobutylene, poly(1-butene), polyvinylcyclohexane, polystyrene, poly(p-methylstyrene), poly(α-methylstyrene), α-olefin copolymers such as ethylene-propylene block copolymers, ethylene-propylene random copolymers, ethylene-butene-1 copolymers, ethylene-4-methyl-1-pentene copolymers, ethylene-butene-propylene terpolymers, ethylene-propylene diene rubbers, and ethylene-hexene copolymers, ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, ethylene-methyl methacrylate copolymers, ethylene-vinyl acetate-methyl methacrylate copolymers, polybutadiene-styrene copolymers, polybutadiene-maleic anhydride copolymers, and ionomer resins. Furthermore, chlorinated polyolefins obtained by chlorinating these polyolefins can also be used.

[0057] As described above, various types of heat-fusible polyolefin B1 can be used, but it is particularly preferable to use modified polyolefin resins in which various functional groups (e.g., carboxyl groups, hydroxyl groups, etc.) have been introduced into polyolefin resins.

[0058] Furthermore, among these modified polyolefin resins, modified polyolefin resins having an acid value of 1 to 200 mgKOH / g (also referred to as acid-modified polyolefin resins) and / or modified polyolefin resins having a hydroxyl value of 1 to 200 mgKOH / g (also referred to as hydroxyl-modified polyolefin resins) can be used because they have improved adhesion to the metal layer and excellent electrolyte resistance.

[0059] Acid-modified polyolefin resins are polyolefin resins that contain carboxyl groups or carboxylic anhydride groups in the molecule, and are synthesized by modifying polyolefins with unsaturated carboxylic acids or their derivatives. The modification methods that can be used include graft modification and copolymerization.

[0060] The acid-modified polyolefin resin is a graft-modified polyolefin obtained by graft-modifying or copolymerizing at least one polymerizable ethylenically unsaturated carboxylic acid or its derivative onto a polyolefin resin before modification.

[0061] Examples of the polyolefin resin before modification include the above-mentioned polyolefin resins, and among them, preferred are propylene homopolymers, copolymers of propylene and α-olefins, ethylene homopolymers, and copolymers of ethylene and α-olefins, etc. These may be used alone or in combination of two or more.

[0062] Examples of acid-modified polyolefin resins include maleic anhydride-modified polypropylene, ethylene-(meth)acrylic acid copolymer, ethylene-acrylic acid ester-maleic anhydride terpolymer, and ethylene-methacrylic acid ester-maleic anhydride terpolymer. Specific examples include "MODIC" manufactured by Mitsubishi Chemical Corporation, "ADMER" and "UNISTOLL" manufactured by Mitsui Chemicals, Inc., "HARDLEN" manufactured by Toyobo Co., Ltd., "UMEX" manufactured by Sanyo Chemical Industry Co., Ltd., "REXPERL EAA" and "REXPERL ET" manufactured by Japan Polyethylene Corporation, "PRIMACOL" manufactured by Dow Chemical Co., Ltd., "NUCREL" manufactured by DuPont-Mitsui Polychemicals, and "BONDINE" manufactured by Arkema.

[0063] Hydroxyl-modified polyolefin resins are polyolefin resins having hydroxyl groups in the molecule, and are synthesized by graft-modifying or copolymerizing polyolefins with hydroxyl-containing (meth)acrylic esters or hydroxyl-containing vinyl ethers, as described below. Examples of the hydroxyl-containing (meth)acrylic esters include hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, glycerol (meth)acrylate, lactone-modified hydroxyethyl (meth)acrylate, polyethylene glycol (meth)acrylate, and polypropylene glycol (meth)acrylate. Examples of the hydroxyl-containing vinyl ethers include 2-hydroxyethyl vinyl ether, diethylene glycol monovinyl ether, and 4-hydroxybutyl vinyl ether.

[0064] A particularly preferred heat-fusible polyolefin resin is a polyolefin in which the heat-fusible polyolefin B1 contains a modified product modified with an acid anhydride, the acid anhydride content is 0.1 to 3 mass %, and the amount of low-molecular-weight components with a number average molecular weight of 1000 or less extracted with acetone is less than 1 mass %.

[0065] If the anhydride content is 0.1% by mass or more, sufficient adhesion to metals is easily obtained, and if it is 3% by mass or less, sufficient mechanical properties such as rigidity and strength are easily obtained.If the amount of extracted low molecular weight components is less than 1% by mass, the low molecular weight components are less likely to bleed out onto the surface of the heat-sealable layer, and adhesion is less likely to be impaired.

[0066] [Other Resins B2] Layer B may contain 0 to 30 mass % of another resin B2 other than the heat-fusible polyolefin B1. In other words, the heat-fusible layer can contain another resin B2 that has appropriate compatibility or dispersibility with the heat-fusible polyolefin B1, as long as the object of the present invention is not impaired.

[0067] However, if the amount of other resin B2 is too large, it may reduce the inherent adhesive strength when bonding metals together, and providing Layer C, which is an easy-adhesion layer, has the effect of reducing the amount of other resin components added to Layer B. From this perspective, the upper limit of the amount of resin B2 contained in the heat-sealable layer is 30% by mass, preferably 25% by mass, more preferably 20% by mass, and particularly preferably 10% by mass. There is no particular lower limit, but as long as the adhesive strength appropriate for the intended use can be ensured, it may be 0% by mass.

[0068] Examples of resin B2 include polyamide, polyester, polyurethane, 4-methyl-1-pentene polymer (polymer A1), copolymer C1 (a copolymer of 4-methyl-1-pentene and an α-olefin) described below, polyolefins other than polymer A1 and copolymer C1, ethylene propylene diene rubber, fluororubber, and silicone rubber.

[0069] Layer B may be composed of resin alone, but may also contain stabilizers such as tackifiers, antistatic agents, antioxidants, metal deactivators, dehydrating agents, and antacid adsorbents, or additives such as crosslinking agents, chain transfer agents, nucleating agents, lubricants, plasticizers, fillers, reinforcing materials, pigments, dyes, and flame retardants, within the range that does not impair the effects of the present invention.

[0070] [C layer (easy adhesion layer)] Layer C, which is an easy-adhesion layer, contains copolymer C1 having 60 mol% to 99 mol% of structural units derived from 4-methyl-1-pentene and 1 mol% to 40 mol% of structural units derived from an α-olefin having 2 to 20 carbon atoms other than 4-methyl-1-pentene.

[0071] The copolymer C1 may be contained in the C layer in an amount of 100 to 50% by mass, but from the viewpoint of increasing the adhesion to the A layer and the B layer, the copolymer C1 is preferably contained in the C layer in an amount of 100 to 80% by mass, more preferably 100 to 90% by mass, and most preferably 100% by mass.

[0072] Layer C may contain 0 to 50% by mass of other resin C2, but from the viewpoint of increasing adhesion to layers A and B, layer C preferably contains 0 to 20% by mass of resin C2, more preferably 0 to 10% by mass, and most preferably does not contain other resin C2.

[0073] It is preferable that Layer C does not contain any components other than the resin component, but it may contain antioxidants, stabilizers, crosslinking agents, lubricants, metal deactivators, nucleating agents, etc., as long as the effects of Layer C are not impaired.

[0074] The C layers provided on both sides of the A layer may have the same or different compositions, but for example, when heat-sealable layers of the same material and thickness are provided on both surfaces, it is preferable to provide C layers of the same composition on both sides. Also, the thicknesses of the C layers may be the same or different, but in such cases, it is preferable to provide C layers of the same thickness on both sides.

[0075] In order to obtain an appropriate thickness ratio relative to layer B, the thickness of layer C is preferably 0.5 μm or more, more preferably 1 μm or more, and even more preferably 2 μm or more, and is preferably 15 μm or less, more preferably 12 μm or less, and even more preferably 10 μm or less.

[0076] [Copolymer C1] Copolymer C1 may be the same as or different from polymer A1, but from the viewpoint of improving adhesion to layers A and B, copolymer C1 preferably has a lower mol% of structural units derived from 4-methyl-1-pentene than polymer A1, more preferably 10 mol% or more lower, and even more preferably 20 mol% or more lower.

[0077] Examples of the α-olefins having 2 to 20 carbon atoms, which are constituent components of copolymer C1, include ethylene, propylene, 1-butene, 1-hexene, 1-octene, 1-decene, 1-tetradecene, and 1-octadecene. The α-olefins are preferably ethylene, propylene, 1-butene, 1-hexene, 1-octene, and 1-decene, more preferably ethylene, propylene, 1-butene, 1-hexene, and 1-octene, and even more preferably ethylene, propylene, 1-butene, and 1-hexene. The α-olefins may be used alone or in combination of two or more thereof.

[0078] In Copolymer C1, the content of structural units derived from 4-methyl-1-pentene is 60 mol% to 99 mol%, preferably 63 mol% to 98 mol%, more preferably 65 mol% to 95 mol%, even more preferably 65 mol% to 90 mol%, and particularly preferably 65 mol% to 87 mol%. The content of structural units derived from α-olefins having 2 to 20 carbon atoms other than 4-methyl-1-pentene is 1 mol% to 40 mol%, preferably 2 mol% to 37 mol%, more preferably 5 mol% to 35 mol%, even more preferably 10 mol% to 35 mol%, and particularly preferably 13 mol% to 35 mol%. When the amount of these structural units is within the above range, Layer C exhibits superior adhesion to Layers A and B.

[0079] The copolymer C1 may be an amorphous copolymer having no melting point, but may have a melting point T mC1 However, the temperature is preferably 199°C or lower, more preferably 100 to 160°C, and even more preferably 110 to 150°C.

[0080] As the copolymer C1, it is particularly preferable to use Absortomer EP1013, EP1001, etc. manufactured by Mitsui Chemicals, Inc.

[0081] [Other Resins C2] Examples of other resins C2 in copolymer C1 include polymer A1, heat-fusible polyolefin B1, 4-methyl-1-pentene resins, polyolefin resins, polyethylene resins, and the like.

[0082] [Characteristics of heat-sealable laminated film] The heat-fusible laminated film of the present invention is characterized in that the melting peak temperature (if there are multiple melting peak temperatures, the median value between the lowest and highest values) measured by DSC for the heat-fusible polyolefin B1 is used as the melting point T mB1 When T mB1 It is preferable that the thickness deformation rate of the layer A is 5% or less when a load of 3 MPa is applied for 10 minutes at a temperature of +30°C. 5% or less In this case, the amount of change in the dimension in the thickness direction during bonding during thermal bonding is small, and the volume of the shrinkage in the film thickness direction is less likely to act in the direction of expanding in the plane, so the in-plane dimensional change also tends to be small. From this perspective, the film thickness deformation rate of layer A is preferably 3% or less, and more preferably 2% or less. The smaller the film thickness deformation rate, the better, and the most preferred lower limit is 0%, but even 1% or more is within the preferred range.

[0083] As mentioned above, the volume change due to shrinkage in the film thickness direction acts in the direction of in-plane expansion, but because the heat-sealable laminated film is generally solidified in the in-plane direction while retaining residual stress due to the manufacturing method of the heat-sealable laminated film, the in-plane direction generally causes shrinkage behavior. mB1 The in-plane deformation rate at a temperature of +30°C is preferably 4% or less. From this viewpoint, it is more preferably 3% or less, and particularly preferably 2% or less. The smaller the in-plane deformation rate, the better, and the most preferable lower limit is 0%, but a value of 1% or more is also preferable.

[0084] Furthermore, in the heat-sealable laminate film of the present invention, when the thickness of Layer A is tA, the thickness of Layer B is tB, and the thickness of Layer C is tC, it is preferable that the thickness ratio of each layer satisfies the following formula (1) and the following formula (2): 2≦tA / tB≦5 (1) 1≦tB / tC≦100 (2) When tA / tB is 5 or less, the total thickness is not too large, and the sheet is easily cooled during the co-extrusion film formation described below, making it easy to wind up into a roll. Furthermore, when tA / tB is 2 or more, when the heat-sealable layer is melted and bonded to another member, heat is less likely to reach the base layer, making it less susceptible to influences during bonding. From this viewpoint, the upper limit of tA / tB is preferably 4.5 or less, more preferably 4.0 or less, and particularly preferably 3.5 or less. Furthermore, the lower limit of tA / tB is preferably 2.2 or more, more preferably 2.4 or more, and particularly preferably 2.5 or more.

[0085] Furthermore, when tB / tC is 100 or less, that is, when the thickness of the easy-adhesion layer is not extremely thinner than the heat-sealable layer, the easy-adhesion layer diffuses sufficiently into the base layer and the heat-sealable layer, making it easier to increase adhesion. Furthermore, by making the thickness of the C layer equal to or less than that of the heat-sealable layer, it becomes unnecessary to make the C layer unnecessarily thick. From this viewpoint, the upper limit of tB / tC is preferably 80 or less, more preferably 60 or less, and particularly preferably 50 or less. The lower limit of tB / tC is preferably 2 or more, more preferably 3 or more, and particularly preferably 5 or more.

[0086] [Method for manufacturing heat-sealable laminated film] Hereinafter, a detailed description will be given of an example in which a 4-methyl-1-pentene polymer (polymer A1) having a melting point TmA1 of 230° C. or higher is used as the main component of the resin constituting the base layer A.

[0087] The heat-fusible laminate film of the present invention can be produced, for example, by kneading the materials constituting each layer, co-extruding the kneaded mixture, forming an unstretched laminate, and, if necessary, heat-treating the resulting laminate.

[0088] The method for mixing and kneading the 4-methyl-1-pentene polymer (polymer A1), the resin (other resin A2) made of another polyolefin, and any other optional components is not particularly limited, and for example, a single-screw extruder, a twin-screw extruder, a pressure kneader, a Banbury mixer, etc. can be used. Among these, a twin-screw extruder is particularly preferred. The operating conditions of the twin-screw extruder vary depending on various factors such as the type of resin containing polymer A1 and the type and amount of each component contained, and cannot be uniquely determined; however, for example, the operating temperature may be set at about +40°C above the melting point. The screw configuration of the extruder preferably incorporates kneading discs, which provide excellent kneading, at several locations.

[0089] The resin composition constituting the substrate layer can be melt-extruded into a sheet by co-extrusion together with the heat-fusible layer and the easy-adhesion layer, and then cooled and solidified on a casting drum or the like to obtain a heat-fusible laminate film.

[0090] The cooling temperature should be such that all layers are sufficiently solidified, but if the temperature is too low, the sheet-like resin may float, making efficient cooling difficult. From this viewpoint, the cooling temperature is preferably 20 to 120°C, and more preferably 30 to 100°C.

[0091] If necessary, after cooling and solidifying, mA1 -100~T mA1 By carrying out the heat treatment at -5°C for 1 to 60 seconds, it becomes easy to control the in-plane deformation rate of the heat-fusible laminated film within a predetermined range. The heat treatment method may be a roll conveying type or a floating type, but the floating type is preferred from the viewpoint of being able to relax the in-plane direction and preventing the heat-fusible layers on both sides from sticking to each other.

[0092] The heat-fusible laminate film of the present invention is characterized in that at least the easy-adhesion layer is formed by co-extrusion with the base layer, and preferably the easy-adhesion layer and the heat-fusible layer are formed by co-extrusion with the base layer. In conventional methods, the easy-adhesion layer may be formed by a method other than co-extrusion, in which case the adhesion between the easy-adhesion layer and the base layer becomes insufficient.

[0093] When the heat-fusible layer is laminated later, the lamination method can be dry lamination or wet lamination, and the coating method can be extrusion resin coating, molten resin coating, or coating liquid coating. However, in these methods, lamination must be performed according to the substrate layer having a specific width in the width direction, so the substrate layer must be manufactured once, and then the heat-fusible layer must be provided in a separate process. Furthermore, due to the width restriction, the area that can be produced per unit time is often restricted. Therefore, even considering the manufacturing process, it is preferable to form the easy-adhesion layer and the heat-fusible layer together with the substrate layer by co-extrusion.

[0094] In the present invention, when resins are co-extruded to provide a heat-sealable layer, it is preferable to melt-extrude the resins by adjusting the melt temperature appropriately according to the viscosity of the base layer. It is also preferable to select the type and molecular weight of the heat-sealable polyolefin B1 and the other resin B2 so that the melt viscosity of the heat-sealable layer is appropriate.

[0095] Furthermore, when extruding resins by coextrusion to provide an easy-adhesion layer, it is preferable to melt-extrude the resins by adjusting the melt temperature appropriately according to the viscosity of the base layer. It is also preferable to select the type and molecular weight of copolymer C1 and other resin C2 so that the melt viscosity of the easy-adhesion layer is appropriate.

[0096] The operating temperature (melting temperature) of the extruder for the heat-sealable layer is the melting point T mB1 In contrast, T mB1 +20℃~T mB1 +120℃ is preferred, T mB1 +50℃~T mB1 +100°C is more preferable.

[0097] The operating temperature (melting temperature) of the extruder for the adhesive layer is the melting point T mC1 In contrast, T mC1 +20℃~T mC1 +120℃ is preferred, T mC1 +50℃~T mC1 +100°C is more preferable.

[0098] The amount of the melted heat-fusible layer and the easily adhesive layer extruded from the extruder is determined appropriately depending on the thickness ratio relative to the base layer, the thickness of the laminate, the line speed, and the like.

[0099] [roll] The roll of the present invention is formed by winding the above-described heat-sealable laminate film in the longitudinal direction. That is, the heat-sealable laminate film of the present invention is preferably produced continuously.

[0100] [Application] The heat-fusible laminate film of the present invention can be used to thermally bond various adherends. Examples of the adherends include various metals, various resins, fiber-reinforced resins including glass fibers, ceramics, etc. Examples of the shape of the adherends include sheets, films, flat plates, and three-dimensional shapes having flat portions or curved portions formed by bending a flat surface.

[0101] Thermal bonding using a heat-fusible laminate film is carried out at a temperature above the softening temperature of the heat-fusible layer. Furthermore, when thermal bonding is carried out at a temperature at which the base layer is thermally deformed, it becomes possible to thermally bond to adherends with more complex surface shapes. [Example]

[0102] The present invention will be described in more detail below with reference to examples and comparative examples. In the present invention, physical properties were measured or evaluated by the following methods. Unless otherwise specified, "parts" means "parts by mass" and "%" means "% by mass."

[0103] (1) Film, thickness of each layer, and layer thickness composition ratio The film was cut at low temperature using an ice-embedded microtome to obtain a cross section perpendicular to the film surface. The film cross section was observed using a stereomicroscope and photographed at an appropriate magnification so that the entire film thickness was visible in one field of view. From this image, the thickness of each layer was measured using a scale. Measurements were taken for three independently prepared cross-sectional samples, and the average value was used as the layer thickness of the laminated film. The layer thickness composition ratios tA / tB and tB / tC were also calculated using the layer thicknesses.

[0104] (2-1) Melting point A 10 mg resin sample was collected and subjected to DSC measurement using a DSC device (Q100 manufactured by TA Instruments) at a heating rate of 10°C / min. From the obtained chart, the peak top of the endothermic peak was defined as the melting point and calculated.

[0105] (2-2) Melting point T of heat-sealable polyolefin B1 mB1 The melting peak temperature of the heat-fusible polyolefin B1 measured by DSC in the same manner as in (2-1) above was taken as the melting point T mB1 However, when there were multiple melting peak temperatures, the median value between the lowest and highest values ​​was used.

[0106] (3) Thickness deformation rate of layer A The obtained heat-sealable laminated film was cut into 10 mm x 10 mm pieces, and 30 pieces were stacked together and placed in a compression creep tester (manufactured by A&D Co., Ltd., CP6-L-250) at 3 MPa and 160°C (melting point T mB1 A load was applied in the film thickness direction for 10 minutes under the conditions of (130°C) + 30°C). At this time, the time when a weight equivalent to 3 MPa was finally placed after conditioning to the environmental conditions was set as 0 minutes, and the measurement was carried out for 10 minutes. After the load application treatment, the thickness of Layer A of the sample was measured using the method described in (1) above, and the amount of displacement from the initial film thickness was calculated. The film thickness deformation rate of Layer A was calculated using the following formula. Film thickness deformation rate (%) = (initial film thickness - film thickness after treatment) / initial film thickness × 100

[0107] (4) In-plane deformation rate A sample of 200 mm x 200 mm was taken parallel to the machine direction (MD) and the transverse direction (TD), and gauge marks (gauge distance: 100 mm) were made in the machine direction (MD) and the transverse direction (TD). After that, the sample was heated to 160 °C (melting point T mB1 The specimens were then treated for 30 seconds in a thermostatic chamber set at (130°C) + 30°C, and the gauge length was measured. The gauge length before heat treatment was used as the reference, and the 160°C thermal deformation rate (%) in the machine direction (MD) and transverse direction (TD) was calculated from the change in the gauge length.

[0108] (5) Adhesion (5-1) Initial adhesion Adhesion was evaluated using SUS316 as the adherend. To prepare the test pieces, the resulting heat-sealable laminate film was sandwiched between two 0.1 mm thick SUS316 sheets cut to 150 mm x 150 mm using a press, and the two sheets were bonded together at 160°C and a pressure of 5 MPa for 1 minute. This molded sample was cut into a 10 mm wide and 100 mm long test piece. The edge of the SUS316 adherend for adhesion measurement was held, and a 180° peel test was performed at a peel rate of 100 mm / min using a tensile tester (Orientec Co., Ltd., Tensilon UCT-100) in accordance with JIS-C2151. The measurement was performed five times, and the average of the maximum values ​​was used as the peel strength, which was evaluated according to the following criteria.

[0109] A: Peeling force is 10N or more B: Peeling force is 3N or more but less than 10N C: Peeling force is less than 3N In the case of the evaluation results B and C above, peeling was found between the A layer and the C layer by visual inspection. (5-2) Durability in a humid and hot environment (121°C x 48 hours) The same procedure as in (5-1) above was carried out, except that a sample piece (10 mm wide, 100 mm long) of the SUS316 adherend prepared in (5-1) above was used, which was immersed in water at 121°C for 48 hours and then left to dry at room temperature for 24 hours. Evaluation was then carried out according to the following criteria.

[0110] A: Peeling force is 10N or more B: Peeling force is 3N or more but less than 10N C: Peeling force is less than 3N In the case of the evaluation results B and C above, peeling was found between the A layer and the C layer by visual inspection.

[0111] (6) Amount of low molecular weight component extracted The dissolved components were extracted using a Soxhlet extraction for 2 hours using acetone that had been evaporated and cooled in a 90°C hot water bath, and the resulting solution was used to confirm the presence of low-molecular-weight components with a number-average molecular weight of 1,000 or less using an apparatus (Waters e2695). The amount of extracted low-molecular-weight components (mass %) was calculated from the mass of the sample.

[0112] [Manufacturing Example 1] A homopolymer of 4-methyl-1-pentene, PMP (melting point 242°C), was prepared as follows.

[0113] A 1-liter polymerization vessel that had been thoroughly purged with nitrogen was charged with 400 ml of 4-methyl-1-pentene, 300 ml of hydrogen, 0.5 mmol of triethylaluminum, and 1.0 mmol of titanium (III) chloride, and the temperature inside the polymerization vessel was maintained at 60°C. After polymerization for 1 hour, the powder was removed from the polymerization vessel, filtered, washed with hexane, and dried overnight at 80°C under reduced pressure to obtain 113.9 g of polymer.

[0114] [Example 1] As the polymer A1 for forming the base layer A, a polymer containing 100 mass% of polymethylpentene (TPX) (DX845 manufactured by Mitsui Chemicals, Inc., a 4-methyl-1-pentene copolymer copolymerized with a few mol% of a C10 α-olefin, melting point 233°C) was used, which was fed into an extruder and melt-kneaded at a melting temperature of 280°C. Furthermore, as the heat-fusible polyolefin B1 for forming the heat-fusible layer B, a modified polyolefin resin (Hardlen M100 manufactured by Toyobo Co., Ltd., melting peak temperatures of 110°C, 130°C, and 150°C, melting point T mB1A copolymer containing 100% by mass of an acid anhydride content of 1% by mass and an extracted amount of low molecular weight components of 0.3% by mass was used, and the copolymer was fed into an extruder and melt-kneaded at a melting temperature of 230°C. Furthermore, as copolymer C1 for forming layer C, which is an easily adhesive layer, a copolymer containing 100% by mass of a 4-methyl-1-pentene copolymer (manufactured by Mitsui Chemicals, Inc., EP1013, 85 mol% 4-methyl-1-pentene, 15 mol% α-olefin having 10 carbon atoms) was used, and the copolymer was fed into an extruder and melt-kneaded at a melting temperature of 200°C.

[0115] Co-extrusion was performed with each die slit positioned so that the layers were in direct contact with each other to form a layer structure of B / C / A / C / B, and the resulting mixture was cooled and solidified on a casting drum set at a surface temperature of 60°C to produce an unstretched film. The extrusion rate was controlled so that the thickness composition of the unstretched film would be 30 / 5 / 75 / 5 / 30.

[0116] The unstretched film was wound into a roll to obtain a roll of heat-sealable laminated film. The properties of the obtained heat-sealable laminated film are summarized in Table 1.

[0117] [Example 2] A roll of heat-sealable laminated film was obtained in the same manner as in Example 1, except that 90 mass% of a modified polyolefin resin (Hardlen M100, manufactured by Toyobo Co., Ltd.) was used as the heat-sealable polyolefin B1 for forming Layer B, and 10 mass% of a 4-methyl-1-pentene copolymer (EP1013, manufactured by Mitsui Chemicals, Inc.) was used as the other resin B2. The properties of the obtained heat-sealable laminated film are summarized in Table 1.

[0118] [Example 3] A roll of heat-sealable laminate film was obtained in the same manner as in Example 1, except that the discharge amount of Layer B / Layer C / Layer A / Layer C / Layer B was changed to obtain a heat-sealable laminate film with a thickness of 160 μm. The properties of the obtained heat-sealable laminate film are summarized in Table 1.

[0119] [Example 4] A roll of heat-sealable laminated film was obtained in the same manner as in Example 1, except that the polymer A1 for forming Layer A contained 90 mass% polymethylpentene (DX845, manufactured by Mitsui Chemicals, Inc.) and the other resin A2 contained 10 mass% polypropylene resin (FS2011DG3, manufactured by Sumitomo Chemical Co., Ltd.). The properties of the obtained heat-sealable laminated film are summarized in Table 1.

[0120] [Example 5] A roll of a heat-sealable laminated film was obtained in the same manner as in Example 1, except that the polymer A1 for forming Layer A contained 100 mass % of the polymethylpentene homopolymer PMP (melting point 242°C) obtained in Production Example 1. The properties of the obtained heat-sealable laminated film are summarized in Table 1.

[0121] [Example 6] A roll of heat-sealable laminated film was obtained in the same manner as in Example 5, except that 90 mass% of a 4-methyl-1-pentene copolymer (EP1013, manufactured by Mitsui Chemicals, Inc.) was used as copolymer C1 for forming layer C, and 10 mass% of a modified polyolefin resin (Hardlen M100, manufactured by Toyobo Co., Ltd.) was used as other resin C2. The properties of the obtained heat-sealable laminated film are summarized in Table 1.

[0122] [Example 7] A roll of heat-sealable laminate film was obtained in the same manner as in Example 1, except that the discharge amounts of Layer B / Layer C / Layer A / Layer C / Layer B were changed to obtain a heat-sealable laminate film with a thickness of 298 μm. The properties of the obtained heat-sealable laminate film are summarized in Table 1.

[0123] [Example 8] In Example 1, a roll of heat-sealable laminated film was obtained in the same manner as in Example 1, except that the copolymer C1 used to form the C layer was a 4-methyl-1-pentene copolymer (EP1001, manufactured by Mitsui Chemicals, Inc., 72 mol% 4-methyl-1-pentene, 28 mol% α-olefin, no melting point) containing 100% by mass, the heat-sealable polyolefin B1 used to form the B layer was a modified polyolefin resin (Hardlen M100, manufactured by Toyobo Co., Ltd.) containing 90% by mass, and the other resin B2 used was a 4-methyl-1-pentene copolymer (EP1001, manufactured by Mitsui Chemicals, Inc.) containing 10% by mass. The properties of the obtained heat-sealable laminated film are summarized in Table 1.

[0124] [Example 9] A roll of a C layer / A layer / C layer laminate film was obtained in the same manner as in Example 1, except that a 85 μm thick laminate film consisting of three layers, C layer / A layer / C layer, was obtained without providing Layer B in Example 1. Furthermore, a roll of a heat-sealable layer film was obtained in the same manner as in Example 1, except that a 30 μm thick heat-sealable layer film consisting of Layer B, which is a heat-sealable layer, was obtained without providing Layers A and C in Example 1.

[0125] The roll of the laminate film was unwound, and then a roll of the heat-sealable layer film was unwound so that Layer B would be bonded to both sides of the roll. A heated roll wrapped in a Teflon (registered trademark) tube was heated to 180°C and laminated while nipping, producing a roll of heat-sealable laminate film consisting of Layer B / Layer C / Layer A / Layer C / Layer B. The properties of the heat-sealable laminate film obtained by this method are summarized in Table 1.

[0126] [Comparative Example 1] A roll of heat-sealable laminated film was obtained in the same manner as in Example 1, except that the polymer A1 for forming Layer A contained 30 mass% polymethylpentene (DX845, manufactured by Mitsui Chemicals, Inc.) and the other resin A2 contained 70 mass% polypropylene resin (FS2011DG3, manufactured by Sumitomo Chemical Co., Ltd.). The properties of the obtained heat-sealable laminated film are summarized in Table 1. Note that the thickness deformation rate could not be measured because the thickness deformation of Layer A was extremely large.

[0127] Comparative Example 2 A roll of heat-sealable laminate film was obtained in the same manner as in Example 1, except that a heat-sealable laminate film having a thickness of 165 μm was obtained by changing the discharge amount of Layer B / Layer A / Layer B without providing Layer C. The properties of the obtained heat-sealable laminate film are summarized in Table 1. Note that when measuring the durable adhesion under a humid and hot environment, peeling occurred between Layer B and Layer A, making it impossible to measure the durable adhesion.

[0128] Comparative Example 3 A roll of heat-sealable laminated film was obtained in the same manner as in Example 1, except that copolymer C1 for forming layer C, which is an easy-adhesion layer, was not used, and a resin containing 100 mass% of polypropylene resin (FS2011DG3, manufactured by Sumitomo Chemical Co., Ltd.) was used as other resin C2. The properties of the obtained heat-sealable laminated film are summarized in Table 1. Note that when measuring the durable adhesion under a humid and hot environment, peeling occurred between layer C and layer A, making it impossible to measure the durable adhesion.

[0129] Comparative Example 4 A roll of a C layer / B layer laminate film was obtained in the same manner as in Example 1, except that a 35 μm thick laminate film consisting of two layers, C layer / B layer, was obtained without providing Layer A in Example 1. Furthermore, a roll of a base layer film was obtained in the same manner as in Example 1, except that a 75 μm thick base layer film consisting of Layer A as a base layer was obtained without providing Layer C / B in Example 1.

[0130] A roll of base layer film was unwound, and a roll of laminated film was unwound so that Layer C was bonded to both sides of the roll. A heated roll wrapped in a Teflon (registered trademark) tube was heated to 180°C and laminated while nipping, producing a roll of heat-sealable laminated film consisting of Layer B / Layer C / Layer A / Layer C / Layer B. The properties of the heat-sealable laminated film obtained by this method are summarized in Table 1. Note that because Layer C and Layer A peeled off, it was not possible to measure the initial adhesion and durable adhesion.

[0131] [Table 1]

[0132] As is clear from Table 1, in Examples 1 to 9, heat-sealable laminate films were obtained that had high adhesion at the lamination interface initially and in a humid and hot environment, and that had a good bonded state when heat-sealed.

[0133] In contrast, in Comparative Example 1, in which the content of the 4-methyl-1-pentene polymer in the base layer was low, the film thickness deformation rate of the base layer was extremely large, and the in-plane deformation rate of the heat-sealable laminate film was also large, resulting in a poor bonding state after heat fusion.

[0134] Furthermore, in Comparative Example 2 in which no easy-adhesion layer was provided and Comparative Example 3 in which the easy-adhesion layer did not contain the 4-methyl-1-pentene copolymer, the adhesion strength at the lamination interface decreased initially and in a humid and hot environment. Furthermore, in Comparative Example 4 in which the base material layer and the easy-adhesion layer were thermally laminated, the adhesion strength at the lamination interface also decreased significantly initially and in a humid and hot environment. [Industrial Applicability]

[0135] The heat-sealable laminate film of the present invention has excellent adhesive strength without causing peeling between layers to various flat or film-like substrates, including metals, glass, and resins with or without fiber reinforcement, and can suppress bonding defects by maintaining a small film thickness deformation rate of the base layer that can withstand the heat during bonding molding, and therefore has high industrial applicability.

Claims

1. A heat-sealable laminated film comprising a B layer, a C layer, an A layer, a C layer, and a B layer in this order, wherein at least the C layer, the A layer, and the C layer are laminated by coextrusion, the layer A contains 100 to 70 mass % of a polymer A1 having 90 mol % or more and 100 mol % or less of structural units derived from 4-methyl-1-pentene, based on all structural units; The layer B contains 100 to 70 mass % of a heat-fusible polyolefin B1, the C layer contains 50 mass % or more of a copolymer C1 having 60 mol % or more and 99 mol % or less of structural units derived from 4-methyl-1-pentene and 1 mol % or more and 40 mol % or less of structural units derived from an α-olefin having 2 to 20 carbon atoms other than 4-methyl-1-pentene; When the thickness of the A layer is tA, the thickness of the B layer is tB, and the thickness of the C layer is tC, the following formulas (1) and (2) are satisfied: A heat-sealable laminated film, wherein the tA is 45 μm or more. 2≦tA / tB≦5 (1) 1≦tB / tC≦100 (2)

2. The melting peak temperature (if there are multiple melting peak temperatures, the median between the lowest and highest values) measured by DSC for the heat-fusible polyolefin B1 is taken as the melting point T ｍＢ１ When T ｍＢ１ 2. The heat-welding laminate film according to claim 1, wherein the thickness deformation rate of the layer A is 5% or less when a load of 3 MPa is applied at a temperature of +30°C for 10 minutes.

3. 3. The heat-fusible laminate film according to claim 1, wherein the polymer A1 contains 100 mol % of structural units derived from 4-methyl-1-pentene based on all structural units.

4. 4. The heat-fusible laminate film according to claim 1, wherein the layer A contains 100% by mass of the polymer A1.

5. The heat-fusible polyolefin B1 contains a modified product modified with an acid anhydride, has an acid anhydride content of 0.1 to 3% by mass, and is a polyolefin in which the amount of low-molecular-weight components having a number average molecular weight of 1000 or less extracted with acetone is less than 1% by mass. The heat-fusible laminate film according to any one of claims 1 to 4.

6. A roll in which the heat-sealable laminate film according to any one of claims 1 to 5 is wound in the longitudinal direction.

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