Hot melt laminated film

Abstract

Provided are a heat-fusible laminated film having high adhesion at a laminated interface and good bonding during heat fusion, and a roll formed by winding the same. The heat-fusible laminated film comprises, in order, a B layer, an A layer, and a B layer laminated by co-extrusion, the A layer containing 100 to 70 mass% of a polymer A1 having 90 mass% or more and 100 mass% or less of a structural unit derived from 4-methyl-1-pentene with respect to the total structural units, the B layer containing 99 to 30 mass% of a heat-fusible polyolefin B1 and 1 to 70 mass% of a copolymer B2 having 60 mass% or more and 89 mass% or less of a structural unit derived from 4-methyl-1-pentene and 11 mass% or more and 40 mass% or less of a structural unit derived from an α-olefin having 2 or more and 20 or less carbon atoms other than 4-methyl-1-pentene.

Description

Technical Field

[0001] The present invention relates to a heat-fusion laminate film having a heat-fusion layer (hereinafter sometimes referred to as "layer B") disposed on both sides of a substrate layer (hereinafter sometimes referred to as "layer A"), and a roll formed therefrom. Background Technology

[0002] Films and sheets with heat-meltability are laminates in which a heat-meltable layer is provided on the outermost surface of at least one side of a substrate. They are used for various purposes, such as packaging and reinforcement, to bond the heat-meltable layer to adherents formed of resin or metal. The substrate is selected based on the intended use, but resin substrates are most commonly used, with the appropriate resin chosen according to the required properties.

[0003] Furthermore, to achieve excellent adhesion to the adherend, high adhesion is required not only between the adherend and the thermoplastic layer, but also between the substrate and the thermoplastic layer. This is because external stresses that could cause complete peeling will disrupt or cause the weakest areas of adhesion to break down or peel off.

[0004] In order to obtain excellent adhesion between the substrate and functional layers such as the heat-welding layer, methods are known to activate the substrate surface by corona treatment, plasma treatment, etc., or to provide an easy-to-adhere layer on the substrate surface, or to provide an intermediate layer between the substrate and the heat-welding layer (Patent Documents 1-2).

[0005] In addition, when the thermally bondable layer and the substrate have high adhesion, there is a known method for manufacturing a laminate in which the two layers are directly in contact by co-extruding the resin constituting the two layers (Patent Documents 3-4).

[0006] Furthermore, there are also known heat-weld laminated films in which a 4-methyl-1-pentene polymer or a 4-methyl-1-pentene copolymer is used in the substrate layer to improve the heat resistance of the substrate layer, and other resin components are contained in the substrate layer to improve the adhesion of the substrate layer.

[0007] For example, Patent Document 5 proposes a thin film for a battery component comprising a substrate layer formed of a resin composition (X) between two weldable layers formed of a modified polyolefin, wherein the resin composition (X) comprises a 4-methyl-1-pentene polymer (A) and polypropylene (C), and the content of polymer (A) is 0.5% by mass or more and 50% by mass or less.

[0008] In addition, Patent Document 6 proposes a laminated film for tab leads, which has a heat-resistant resin layer (C) between a heat-melting resin layer (A) containing a modified polypropylene resin or the like and a similar heat-melting resin layer (B). The heat-resistant resin layer (C) contains a copolymer of 4-methyl-1-pentene and α-olefin and an α-olefin resin (1) with a melting point of 30°C to 110°C, wherein the content of the copolymer is 40 parts by weight or more and 90 parts by weight or less.

[0009] Existing technical documents

[0010] Patent documents

[0011] Patent Document 1: International Publication No. WO2019 / 078134

[0012] Patent Document 2: Japanese Patent No. 6688574

[0013] Patent Document 3: Japanese Patent No. 6331468

[0014] Patent Document 4: Japanese Patent No. 2530732

[0015] Patent Document 5: Japanese Patent Application Publication No. 2016-126995

[0016] Patent Document 6: Japanese Patent No. 6484081 Summary of the Invention

[0017] The problem the invention aims to solve

[0018] However, in the technical solution of Patent Document 5, based on the necessity of ensuring the tightness of the adhesion between the substrate layer and the heat-fusion bonding layer, the content of polypropylene (C) contained in the substrate layer needs to be a certain level or above. Therefore, it cannot be said that the heat resistance and mechanical properties of the substrate layer are sufficient when performing heat fusion.

[0019] Furthermore, in the technical solution of Patent Document 6, since the resin composition of the heat-melting resin layer is a typical resin composition, if a 4-methyl-1-pentene copolymer with a melting point of 230°C or higher is used in the substrate layer, and a 4-methyl-1-pentene copolymer with a melting point of 200°C or lower (HR-4 and 5 used in the examples) is not used in combination, the adhesive strength (adhesion) will become insufficient, as in Comparative Example 2 using HR-8. That is, it is difficult to simultaneously improve the heat resistance, mechanical properties, and adhesion of the substrate layer.

[0020] Therefore, the object of the present invention is to provide a heat-weldable laminated film with high adhesion at the laminated interface and good bonding state during heat fusion, and a roll formed therefrom.

[0021] Solution for solving the problem

[0022] In order to solve the above-mentioned technical problems, the inventors conducted in-depth research and found that the above-mentioned technical problems could be solved by co-extruding a substrate layer containing polymethylpentene resin and a thermoplastic layer containing a thermoplastic polyolefin and a copolymer of 4-methyl-1-pentene and other α-olefins, thereby completing the present invention.

[0023] That is, the present invention contains the following contents.

[0024] [1] A heat-weldable laminated film, comprising, in sequence, a B layer, an A layer, and a B layer laminated by co-extrusion.

[0025] The A layer contains 100–70% by mass of polymer A1, wherein polymer A1 has structural units derived from 4-methyl-1-pentene at a rate of 90 mol% to 100 mol% relative to all structural units.

[0026] The B layer contains 99-30% by mass of a heat-melting polyolefin B1 and 1-70% by mass of a copolymer B2, wherein the copolymer B2 has 60 mol% and 89 mol% of structural units derived from 4-methyl-1-pentene and 11 mol% and 40 mol% of structural units derived from α-olefins other than 4-methyl-1-pentene, having 2 or more and 20 or fewer carbon atoms.

[0027] [2] According to the heat-fusion weldable laminated film described in [1], wherein the melting peak temperature of the heat-fusion weldable polyolefin B1 determined by DSC (wherein, in the case of multiple melting peak temperatures, it is the intermediate value between the lowest and highest values) is set as the melting point T. mB1 At that time, in T mB1 The film thickness deformation rate of layer A when subjected to a 3MPa load for 10 minutes at +30℃ is less than 5%.

[0028] [3] The heat-weldable laminated film according to [1] or [2], wherein the polymer A1 has 100 mol% of structural units derived from 4-methyl-1-pentene relative to all structural units.

[0029] [4] A heat-weldable laminated film according to any one of [1] to [3], wherein the A layer contains 100% by mass of the polymer A1.

[0030] [5] A heat-weldable laminated film according to any one of [1] to [4], wherein when the film thickness of layer A is set to tA and the film thickness of layer B is set to tB, the following formula (1) is satisfied.

[0031] 2≤tA / tB≤5 (1).

[0032] [6] The heat-melting laminated film according to any one of [1] to [5], wherein the heat-melting polyolefin B1 is a polyolefin comprising a modified product modified with an anhydride, an anhydride content of 0.1 to 3% by mass, and an extraction amount of a low molecular weight component of less than 1% by mass based on an acetone number average molecular weight of less than 1000.

[0033] [7] A roll, which is formed by winding a heat-fusion laminated film as described in any one of [1] to [6] along its length.

[0034] The effects of the invention

[0035] According to the present invention, it is possible to provide a heat-weldable laminated film with high adhesion at the laminated interface and good bonding state during heat fusion, as well as a roll formed therefrom.

[0036] The detailed reasons are not yet clear, but they can be considered as follows. For layer A, which is mainly composed of polymer A1 with structural units derived from 4-methyl-1-pentene, once it becomes a cured film, it tends to have high crystallinity, resulting in low surface energy. This makes it difficult to fully wet the heat-melting resin layer or to diffuse the heat-melting layer B in layer A, thus making it difficult to bond.

[0037] However, if layers A and B are in a molten state, the highly compatible components contained in layers A and B can diffuse into each other at the interface to achieve a tight bond. Therefore, by co-extruding layers A and B and stacking them in a molten state, high adhesion between the layers can be achieved. Furthermore, the heat-weldable layer B exhibits good adhesion when bonded to metals, thus improving durability under initial and humid conditions. In addition, since the copolymer component of the aforementioned polymer A1 is low, crystallinity can be increased, thereby improving mechanical properties even in an unstretched form. When the heat-weldable layer B is heat-welded, the film thickness deformation rate of layer A can be reduced, and since it is unstretched, the in-plane thermal deformation rate can also be reduced. As a result, the bonding state during heat fusion becomes excellent. Detailed Implementation

[0038] The present invention will now be described in detail. It should be noted that, for ease of explanation, the film-forming direction is sometimes referred to as the mechanical axis direction, longitudinal direction, length direction, or MD direction; and sometimes the direction orthogonal to the film-forming direction and thickness direction is referred to as the width direction, transverse direction, or TD direction. Furthermore, the various physical properties described in this specification are specifically measured using the methods described in the examples.

[0039] [Thermo-Melt Laminated Films]

[0040] The heat-weldable laminated film of the present invention is a heat-weldable laminated film comprising layers B, A, and B stacked sequentially by co-extrusion. That is, the heat-weldable laminated film only needs to include layer A as a substrate layer and layer B as a heat-weldable layer in the order of layer B, layer A, and layer B.

[0041] Therefore, other layers can be included. For example, a protective film, a release film, a cover film, etc. can be provided on the surface side of layer B. Alternatively, the materials to be bonded can be pre-heat-bonded to one side.

[0042] Furthermore, in thermally bondable laminated films, layers B, A, and B can be directly laminated via co-extrusion. However, the state of each layer can also be imagined as a state of interdiffusion of the components contained in each layer, and a state in which a concentration gradient is generated in the components contained in layer B. In particular, even if the copolymer B2 contained in layer B is relatively small, due to the significant improvement in adhesion, it can be inferred that copolymer B2 generates a concentration gradient in a manner where its concentration increases on the A layer side.

[0043] The definition of "layered by co-extrusion" in this invention defines the structure of the product through the manufacturing method. However, as described below, there are cases where the product cannot be directly defined by its structure or characteristics, or where it is almost impractical.

[0044] In the case of a three-layer laminated film manufactured by co-extrusion, the adhesion at the lamination interface differs from that of a laminated film formed by thermally laminating two other layers onto a pre-manufactured substrate film, indicating a difference in microstructure. That is, it is assumed that when observing the molecules at the lamination interface in terms of microstructure, the diffusion / intrusion states of the components in each layer differ, thus resulting in different adhesion. However, since the difference in diffusion states is a difference in degree, it is difficult to structurally define such a difference.

[0045] Therefore, it is impossible to find statements that define the structure or characteristics involved in the differences from the prior art, and it is also impossible or impractical to analyze and define such structure or characteristics based on measurements. Therefore, regarding this invention, at the time of application, there are situations where the product cannot be directly defined by its construction or characteristics, or is practically impractical.

[0046] The following describes the various components of the heat-weldable laminated film of the present invention.

[0047] [Layer A (Substrate Layer)]

[0048] The thermoplastic resin contained in the resin composition constituting layer A, which serves as the substrate layer, can be selected according to the properties required by the substrate layer in the target application. In order to ensure the durability of the substrate layer itself in harsh humid and hot environments, it is preferable not to have functional groups that would become reaction sites for water molecules. In addition, it is preferable to have a high melting point to withstand the heat during bonding and the heat caused by the environment.

[0049] In this invention, from this viewpoint, the main component of the resin composition constituting layer A contains polymer A1, wherein polymer A1 has structural units derived from 4-methyl-1-pentene at a rate of 90 mol% or more and 100 mol% or less relative to all structural units.

[0050] The polymer A1 can be present in the A layer at 100-70% by mass. From the viewpoint of reducing the film thickness deformation rate and the in-plane thermal deformation rate of the A layer, it is preferable to contain 100-80% by mass of polymer A1 in the A layer, more preferably 100-90% by mass, and most preferably 100% by mass. That is, the A layer may also contain 0-30% by mass of other resin A2. For the same reason, it is preferable to contain 0-20% by mass of resin A2 in the A layer, more preferably 0-10% by mass, and most preferably no other resin A2. Moreover, within such a content range, it is easy to obtain the improved heat resistance effect brought by the 4-methyl-1-pentene polymer, and it is easy to obtain a hard film that effectively utilizes the fast crystallization rate.

[0051] On the other hand, increasing the affinity of layer A, which serves as the substrate layer, for the heat-welding layer can further improve the adhesion between the two layers. From this perspective, the content of polymer A1 is preferably 95-75% by mass, more preferably 90-80% by mass. That is, layer A may contain 0-30% by mass of other resin A2, but for the same reason, it is preferable to contain 5-25% by mass of resin A2, more preferably 10-20% by mass of resin A2. Within this content range, the improved heat resistance effect brought by polymer A1 can be maintained to some extent, while simultaneously further improving the adhesion between layer A and the heat-welding layer. In other words, based on the volume ratio of polymer A1 to other resin A2, sufficient adhesion can be easily ensured using polymer A1 as the matrix.

[0052] When the melting point of the substrate layer is set to TmS, and the melting point of the resin constituting the heat-welding layer described later is set to TmHS, if the difference between them is defined as ΔT (=TmS-TmHS), it is preferable to combine them in a range of 0°C to 120°C, more preferably 10°C to 100°C. By setting ΔT to 0°C or higher, for example, it is possible to prevent the substrate layer from melting prematurely due to the heat applied during bonding. In addition, by setting ΔT to 120°C or lower, the difference in melt viscosity will not become too large when melted in an extruder and laminated along the thickness direction, thus suppressing the generation of uneven lamination and enabling stable production. From this point of view, it is further preferable that ΔT is 20°C to 90°C, and particularly preferable that ΔT is 40°C to 80°C. Furthermore, the melting point TmS can also be regarded as the melting point T of polymer A1, which is the main component of layer A. mA1 .

[0053] In order to obtain the strength required for the substrate layer where the heat-fusion bonding layer is provided, the thickness of layer A can 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 addition, it is preferably 300 μm or less, more preferably 270 μm or less, and even more preferably 250 μm or less. Furthermore, it can be 150 μm or less or 130 μm or less.

[0054] [Polymer A1]

[0055] Polymer A1 has structural units derived from 4-methyl-1-pentene at a rate of 90 mol% or more and 100 mol% or less relative to all structural units, preferably at a rate of 92 mol% or more and 100 mol% or less, more preferably at a rate of 95 mol% or more and 100 mol% or less.

[0056] As polymer A1, it may further have structural units derived from α-olefins other than 4-methyl-1-pentene, which are 0 mol% or more and 10 mol% or less relative to all structural units, preferably 0 mol% or more and 8 mol% or less, more preferably 0 mol% or more and 5 mol% or less.

[0057] That is, as polymer A1, in addition to homopolymers polymerized with 4-methyl-1-pentene as a monomer, copolymers can also be listed that copolymerize with 90 mol% or more of 4-methyl-1-pentene as a monomer and 10 mol% or less of α-olefins other than 4-methyl-1-pentene as monomers.

[0058] When polymer A1 is a copolymer, α-olefins with 2 or more but less than 20 carbon atoms are preferred as the copolymerizing monomer. Examples of α-olefins that can be copolymerized include one or more of ethylene, propylene, 1-butene, 1-hexene, 1-octene, 1-decene, 1-tetradecene, and 1-octadecene.

[0059] Melting point T of polymer A1 mA1 Preferably, the temperature is 230°C or higher. If a 4-methyl-1-pentene copolymer with a high copolymerization ratio of other monomers is used, the melting point decreases. However, in this case, the crystallization rate decreases, reducing the rigidity of the substrate layer. Therefore, the film thickness deformation rate of layer A increases when bonding metals above the melting point of the heat-welding layer (described later). From this perspective, T mA1 Preferably, the temperature is 231°C or higher, more preferably 232°C or higher, and even more preferably 233°C or higher. There is no upper limit; the product can be a methyl-1-pentene polymer or a 4-methyl-1-pentene copolymer with a lower copolymerization ratio, or the melting point T can be increased by controlling the stereoregularity. mA1 Preferably, the temperature is below 250°C, and more preferably below 245°C.

[0060] When using polymer A1 as the substrate layer, TmS is increased compared to general polypropylene, making it easier to ensure ΔT. However, due to its low surface energy and rapid crystallization rate, it has low affinity with the heat-melt layer, making it difficult to improve adhesion. Therefore, it is particularly effective to provide a heat-melt layer containing copolymer B2 with structural units derived from 4-methyl-1-pentene having a content of 60 mol% to 89 mol% or less, through co-extrusion. Furthermore, it is preferable to incorporate polyolefins or other resins such as A2 into the A layer.

[0061] [Other Resin A2]

[0062] Layer A may contain resin A2 other than polymer A1. As for the other resin A2, it only needs to have adequate compatibility and dispersibility with polymer A1. Examples include polyolefins (including modified polyolefins), copolymers of 4-methyl-1-pentene and α-olefins other than polymer A1 (including copolymer B2), etc., with polyolefins being preferred. Polyolefins are excellent in that they do not have functional groups that could become reaction sites for water molecules. Furthermore, by using polyolefins, dispersibility in polymer A1 is improved.

[0063] Examples of polyolefin resins or modified polyolefin resins include the following. In this specification, "modified" means that the same molecule contains structural units that are different from the structural units of polyolefins, etc.

[0064] Examples of polyolefin resins include 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 or copolymers containing them are also examples. Polypropylene is particularly preferred among these polyolefin resins.

[0065] Especially when blending with 4-methyl-1-pentene polymers (polymer A1) via melt mixing, the same polyolefin resin or modified polyolefin resin can be used. From the viewpoint of compatibility, polypropylene resin copolymerized with 4-methyl-1-pentene or maleic acid modified polypropylene resin is preferred. It should be noted that graft modification and copolymerization can be used as modification methods.

[0066] Specific examples of modified polyolefin resins include maleic anhydride-modified polyethylene, maleic anhydride-modified polypropylene, ethylene / acrylic acid copolymers, ethylene / methacrylic acid copolymers, and copolymers in which part or all of the carboxylic acid portion is a salt formed with sodium, lithium, potassium, zinc, or calcium; ethylene / methyl acrylate copolymers, ethylene / ethyl acrylate copolymers, ethylene / methyl methacrylate copolymers, ethylene / ethyl methacrylate copolymers, and ethylene / ethyl acrylate-g-maleic anhydride copolymers (where "-g-" indicates grafting). (The same applies below), 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-norbornene-g-maleic anhydride copolymer, hydrogenated styrene / butadiene / styrene-g-maleic anhydride copolymer, hydrogenated styrene / isoprene / styrene-g-maleic anhydride copolymer, etc. Among them, maleic acid-modified polypropylene or ethylene-propylene copolymers are particularly preferred.

[0067] As copolymers of 4-methyl-1-pentene and α-olefins other than polymer A1 (including copolymer B2), examples include copolymers having 10 mol% or more and 89 mol% or less of structural units derived from 4-methyl-1-pentene, and 11 mol% or more and 90 mol% or less of structural units derived from α-olefins other than 4-methyl-1-pentene.

[0068] For the α-olefin that is a component of the copolymer, it is preferred to have 2 or more but less than 20 carbon atoms, such as ethylene, propylene, 1-butene, 1-hexene, 1-octene, 1-decene, 1-tetradecene, 1-octadecene, etc. One of the above-mentioned α-olefins may be used, or a combination of two or more of them may be used.

[0069] [Any other components of layer A]

[0070] In layer A, appropriate fillers may be included as needed for purposes such as improving slip properties, provided that the purpose of the invention is not compromised. As fillers, substances known to date as slip-improving agents for films and sheets can be used, such as calcium carbonate, calcium oxide, alumina, kaolin, silicon oxide, zinc oxide, carbon black, silicon carbide, tin oxide, cross-linked acrylic resin particles, cross-linked polystyrene resin particles, melamine resin particles, and cross-linked silicone resin particles. Furthermore, colorants, antistatic agents, antioxidants, organic lubricants, catalysts, etc., may also be appropriately added to layer A. Especially when considering use in humid and hot environments, additives with low leaching properties are preferred.

[0071] In addition, as other arbitrary components, various additives that have been used to date in 4-methyl-1-pentene polymers, etc., can be listed. Such additives include stabilizers, impact modifiers, flame retardants, mold release agents, slip modifiers, colorants, plasticizers, and nucleating agents.

[0072] As another arbitrary component, for example, 0.001 to 10% by mass can be used in layer A.

[0073] [Layer B (Thermo-fusion Layer)]

[0074] Layer B, as the heat-welding layer, contains 99-30% by mass of heat-welding polyolefin B1. From the viewpoint of balancing wet heat durability, adhesion to the adhered material, and interlayer adhesion, it is preferable to contain 98-35% by mass of heat-welding polyolefin B1, more preferably 95-40% by mass, and even more preferably 90-45% by mass. It should be noted that, in this specification, "heat-welding" refers to the property of being able to fuse to the adhered material by heating, and preferably refers to the property of being able to fuse to SUS316, which is a metal, by heating.

[0075] Layer B contains 1 to 70% by mass of copolymer B2, wherein copolymer B2 contains 60 mol% to 89 mol% of structural units derived from 4-methyl-1-pentene and 11 mol% to 40 mol% of structural units derived from α-olefins other than 4-methyl-1-pentene with 2 to 20 carbon atoms. From the viewpoint of balancing wet heat durability, adhesion to the adherend and interlayer adhesion, layer B preferably contains 2 to 65% by mass of copolymer B2, more preferably 5 to 60% by mass, and even more preferably 10 to 55% by mass.

[0076] In addition, layer B may contain other resin B3. In this case, it is preferable to contain 0 to 10% by mass of resin B3, more preferably 0 to 5% by mass, and most preferably no resin B3.

[0077] Layer B, disposed on both sides of layer A, can have the same or different compositions. For example, when bonding objects made of the same material to each other, it is preferable to provide heat-bonding layers with the same composition on both sides. In addition, the thickness of the heat-bonding layers can be the same or different. In the above case, it is preferable to provide heat-bonding layers of the same thickness on both outermost surfaces.

[0078] The thickness of layer B is preferably 100 μm or less. Regarding the adhesion between the heat-welding layer and the substrate layer formed by co-extrusion, although a strong bond can be obtained, in the case of acid-modified polyolefin resins, the acid-modified portion has functional groups that are affected by moisture. Therefore, if the layer is unnecessarily thickened, the heat-welding layer tends to become brittle and break under harsh humid and hot environments. From this viewpoint, the thickness of layer B is preferably 90 μm or less, more preferably 80 μm or less, further preferably 75 μm or less, and particularly preferably 60 μm or less. Furthermore, if the layer is too thin, its mechanical mitigation function in the thickness direction as a heat-welding layer will be weakened; therefore, it is preferably 10 μm or more, more preferably 15 μm or more, and particularly preferably 20 μm or more.

[0079] Layer B is co-extruded onto both sides of the substrate layer, thereby ensuring that the lamination interface on both sides of the substrate layer is in the same state on both sides. This state is more preferable for improving the adhesion of the lamination interface on both sides.

[0080] [Thermo-Melt Polyolefin B1]

[0081] As a heat-melting polyolefin B1, unmodified polyolefin resins can also be used, but modified polyolefins are preferred, and modified polyolefins containing polypropylene are particularly preferred.

[0082] Examples of unmodified polyolefin resins include homopolymers and copolymers of olefins with 2 to 8 carbon atoms, and copolymers of olefins with 2 to 8 carbon atoms with other monomers. Specifically, examples include polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene resin, polypropylene, polyisobutylene, poly(1-butene), polyvinylcyclohexane, polystyrene, poly(p-methylstyrene), poly(α-methylstyrene), 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 rubber, 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 formed by chlorinating these polyolefins can also be used.

[0083] As described above, various types of heat-melting polyolefin B1 can be used, with modified polyolefin resins in which various functional groups (e.g., carboxyl groups, hydroxyl groups, etc.) have been introduced into the polyolefin resin being particularly preferred.

[0084] Furthermore, from the viewpoint of further improving the adhesion to the metal layer and excellent electrolyte resistance, modified polyolefin resins with an acid value of 1 to 200 mg KOH / g (also known as acid-modified polyolefin resins) and / or modified polyolefin resins with a hydroxyl value of 1 to 200 mg KOH / g (also known as hydroxyl-modified polyolefin resins) can be used among these modified polyolefin resins.

[0085] Acid-modified polyolefin resins refer to polyolefin resins containing carboxyl groups and carboxylic anhydride groups in their molecules. They are synthesized by modifying polyolefins with unsaturated carboxylic acids or their derivatives. Grafting modification and copolymerization can be used as modification methods.

[0086] Acid-modified polyolefin resin is a graft-modified polyolefin obtained by grafting or copolymerizing a polyolefin resin before modification with at least one polymerizable olefin unsaturated carboxylic acid or its derivative.

[0087] Examples of polyolefin resins before modification include the aforementioned polyolefin resins, with preferred choices being homopolymers of propylene, copolymers of propylene and α-olefins, homopolymers of ethylene, and copolymers of ethylene and α-olefins. One type may be used alone, or two or more may be used in combination.

[0088] Examples of acid-modified polyolefin resins include maleic anhydride-modified polypropylene, ethylene-(meth)acrylic acid copolymer, ethylene-acrylate-maleic anhydride terpolymer, and ethylene-methacrylate-maleic anhydride terpolymer. Specifically, commercially available resins include "Modic" manufactured by Mitsubishi Chemical Corporation, "ADMER" and "UNISTOLE" manufactured by Mitsui Chemicals Corporation, "HARDLEN" manufactured by Toyobo Corporation, "UMEX" manufactured by Sanyo Chemicals Corporation, "REXPEARL EAA" and "REXPEARL ET" manufactured by Nippon Polyethylene Co., Ltd., "Primacor" manufactured by Dow Chemical Company, "NUCREL" manufactured by DuPont Mitsui Polychemical, and "BONDINE" manufactured by Arkema Corporation.

[0089] Hydroxyl-modified polyolefin resins are polyolefin resins containing hydroxyl groups in their molecules. They are synthesized by grafting or copolymerizing polyolefins with hydroxyl-containing (meth)acrylates or hydroxyl-containing vinyl ethers, as described later. Examples of the aforementioned hydroxyl-containing (meth)acrylates include hydroxyethyl (meth)acrylate; hydroxypropyl (meth)acrylate; glyceryl (meth)acrylate; lactone-modified hydroxyethyl (meth)acrylate; polyethylene glycol (meth)acrylate; and polypropylene glycol (meth)acrylate. Examples of the aforementioned hydroxyl-containing vinyl ethers include 2-hydroxyethyl vinyl ether; diethylene glycol monovinyl ether; and 4-hydroxybutyl vinyl ether.

[0090] As a particularly preferred heat-melting polyolefin resin, the aforementioned heat-melting polyolefin B1 is a polyolefin comprising a modified product modified with an anhydride, an anhydride content of 0.1 to 3% by mass, and an extraction amount of a low molecular weight component with a number average molecular weight of 1000 or less based on acetone of less than 1% by mass.

[0091] If the anhydride content is above 0.1% by mass, sufficient adhesion to the metal can be easily obtained; if it is below 3% by mass, sufficient mechanical properties such as rigidity and strength can be easily obtained. When the extraction amount of low molecular weight components is less than 1% by mass, the low molecular weight components do not easily seep to the surface of the heat-welding layer and do not easily hinder adhesion.

[0092] [Other Resin B2]

[0093] The copolymer B2 has 60 mol% and 89 mol% of structural units derived from 4-methyl-1-pentene and 11 mol% and 40 mol% of structural units derived from α-olefins other than 4-methyl-1-pentene, having 2 or more and 20 carbon atoms.

[0094] From the viewpoint of improving the adhesion between layer A and layer B, it is preferable that the copolymer B2 has a lower molar percentage of structural units derived from 4-methyl-1-pentene than polymer A1, more preferably 10 molar percentages lower, and even more preferably 20 molar percentages lower.

[0095] Examples of α-olefins that are constituents of copolymer B2 and have 2 or more but less than 20 carbon atoms include ethylene, propylene, 1-butene, 1-hexene, 1-octene, 1-decene, 1-tetradecene, and 1-octadecene. Preferably, ethylene, propylene, 1-butene, 1-hexene, 1-octene, and 1-decene are used as the aforementioned α-olefins; more preferably, ethylene, propylene, 1-butene, 1-hexene, and 1-octene are used; and even more preferably, ethylene, propylene, 1-butene, and 1-hexene are used. One type of α-olefin may be used, or a combination of two or more of them may be used.

[0096] In copolymer B2, structural units derived from 4-methyl-1-pentene are 60 mol% or more and 89 mol% or less, preferably 63 mol% or more and 88 mol% or less, more preferably 65 mol% or more and 87 mol% or less, further preferably 65 mol% or more and 86 mol% or less, and particularly preferably 65 mol% or more and 85 mol% or less. Structural units derived from α-olefins (other than 4-methyl-1-pentene) having 2 or more and 20 or less carbon atoms are 11 mol% or more and 40 mol% or less, preferably 12 mol% or more and 37 mol% or less, more preferably 13 mol% or more and 35 mol% or less, further preferably 14 mol% or more and 35 mol% or less, and particularly preferably 15 mol% or more and 35 mol% or less. When the amounts of the above structural units are within the above ranges, the adhesion between layer A and layer B becomes more excellent.

[0097] Copolymer B2 can be an amorphous copolymer without a melting point, and its melting point T is determined by differential scanning calorimetry (DSC) using a melting peak temperature. mB2 Preferably, the temperature is below 199°C, more preferably 100–160°C, and even more preferably 110–150°C.

[0098] As copolymer B2, ABSORTOMER EP1013 and EP1001 manufactured by Mitsui Chemicals Co., Ltd. are particularly preferred.

[0099] [Other resins B3]

[0100] Layer B may contain 0-10% by mass of other resins B3 besides the heat-melting polyolefin B1 and copolymer B2. That is, the heat-melting layer may contain other resins B3 that have moderate compatibility or dispersibility with the heat-melting polyolefin B1 and copolymer B2, as long as it does not impair the purpose of the present invention.

[0101] However, when there is an excessive amount of other resins B3, the effects of the heat-melting polyolefin B1 and copolymer B2 are easily reduced. From this perspective, the upper limit of resin B3 contained in the heat-melting layer is preferably 10% by mass, more preferably 5% by mass, and most preferably 0% by mass.

[0102] Examples of resin B3 include polyamide, polyester, polyurethane, 4-methyl-1-pentene polymers (polymer A1), polyolefins other than polymer A1 and copolymer B2, ethylene-propylene-diene rubber, fluororubber, silicone rubber, etc.

[0103] Layer B may also consist solely of resin, or may contain additives such as tackifiers, antistatic agents, antioxidants, metal passivators, dehydrators, acid adsorbents, etc., or crosslinking agents, chain transfer agents, nucleating agents, lubricants, plasticizers, fillers, reinforcing materials, pigments, dyes, flame retardants, etc., without impairing the effects of the present invention.

[0104] [Characteristics of thermally weldable laminated films]

[0105] In the heat-melting laminated film of the present invention, the melting peak temperature of the heat-melting polyolefin B1 measured by DSC (wherein, in the case of multiple melting peak temperatures, it is the median value between the lowest and highest values) is set as the melting point T. mB1 At that time, in T mB1 The film thickness deformation rate of layer A at +30°C under a 3MPa load for 10 minutes is preferably 5% or less. If the film thickness deformation rate is 5% or less, the change in dimensionality in the thickness direction during thermal bonding is small, and the volume corresponding to the shrinkage in the thickness direction is unlikely to play a role in the direction of in-plane expansion. Therefore, there is a tendency for the in-plane dimensional change to also be small. From this perspective, the film thickness deformation rate of layer A is preferably 3% or less, and more preferably 2% or less. A smaller film thickness deformation rate is more preferred; as a lower limit, 0% is most preferred, but 1% or more is also a preferred range.

[0106] Furthermore, as mentioned above, the volume change corresponding to the amount of shrinkage in the film thickness direction plays a role in the direction of in-plane expansion. However, according to the manufacturing method of thermoplastic laminated films, they are usually cured into films under residual stress in the in-plane direction, thus usually causing shrinkage behavior in the in-plane direction. Therefore, thermoplastic laminated films are preferably manufactured at a melting point T. mB1 The in-plane deformation rate at a temperature of +30°C is 4% or less. From this point of view, it is further preferred to be 3% or less, and particularly preferred to be 2% or less. The smaller the in-plane deformation rate, the better. As a lower limit, 0% is most preferred, but 1% or more is also a preferred range.

[0107] Furthermore, when the thickness of layer A is set to tA and the thickness of layer B is set to tB, the ratio of the thicknesses of each layer in the thermally weldable laminated film of the present invention preferably satisfies the following formula (1).

[0108] 2≤tA / tB≤5 (1)

[0109] If tA / tB is 5 or less, the total thickness will not become too large, making it easier to cool the sheet during the co-extrusion film forming process described later, and easier to roll into a roll. Furthermore, if tA / tB is 2 or more, when the heat-welding layer is melted and bonded to other components, heat is less likely to reach the substrate layer, and it is less susceptible to the effects of bonding. From this perspective, 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.

[0110] [Manufacturing method of thermally fusible laminated films]

[0111] The following is a detailed example of using a 4-methyl-1-pentene polymer (polymer A1) with a melting point TmA1 of 230°C or higher as the main component of the resin constituting the substrate layer, i.e., layer A.

[0112] The heat-weldable laminated film of the present invention can be manufactured, for example, by mixing the materials constituting each layer, co-extruding the mixture, molding the unstretched laminate, and heat-treating it as needed.

[0113] There are no particular limitations on the method of mixing and compounding the 4-methyl-1-pentene polymer (polymer A1) used to form layer A with a resin formed from other polyolefins (other resin A2) and other arbitrary components. 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, the type and amount of each component, etc., and cannot be determined in general. For example, the operating temperature can be set to approximately +40°C relative to the melting point. The screw configuration of the extruder is preferably equipped with multiple kneading discs that provide excellent mixing.

[0114] The method for mixing and compounding the thermoplastic polyolefin B1 and copolymer B2 used to form layer B is the same as the method for compounding layer A, except that the operating temperature of the extruder is set to approximately 100°C above the melting point of thermoplastic polyolefin B1.

[0115] The resin composition constituting the substrate layer can be melt-extruded together with the heat-welding layer into a sheet by co-extrusion, and then cooled and cured using a casting drum or the like to obtain a heat-welding laminated film. As for the cooling temperature, any temperature that allows all layers to be fully cured is acceptable, but if the cooling is too excessive, sheet-like resin may float up, making efficient cooling difficult. From this point of view, 20°C to 120°C is preferred, and 30°C to 100°C is more preferred.

[0116] As needed, after cooling and curing, at T mA1 -100~T mA1 By performing heat treatment at -5°C for 1 to 60 seconds, the in-plane deformation rate of the heat-welding laminated film can be easily controlled within a specified range. The heat treatment method can be either roller conveyor type or floating type; from the viewpoint of mitigating in-plane deformation and preventing adhesion of the heat-welding layers on both sides, the floating type is preferred.

[0117] The thermo-meltable laminated film of the present invention is characterized in that the thermo-meltable layer and the substrate layer are formed together by co-extrusion. In conventional methods, the thermo-meltable layer is sometimes formed by methods other than co-extrusion, in which case the adhesion between the thermo-meltable layer and the substrate layer becomes insufficient.

[0118] Furthermore, in conventional methods, the heat-welding layer is formed using lamination methods such as dry lamination and wet lamination, and coating methods such as extrusion resin coating, melt resin coating, and liquid coating. However, these methods require lamination to match a substrate layer with a specific width in the width direction. Therefore, once the substrate layer is manufactured, the heat-welding layer needs to be formed in another process. Consequently, due to the width limitation, the area that can be produced per unit time is mostly limited. Therefore, even considering the manufacturing process, it is preferable to form the heat-welding layer together with the substrate layer by co-extrusion.

[0119] In this invention, when co-extruding the hot-melt bondable layer, it is preferable to adjust the melt temperature appropriately according to the viscosity of the substrate layer and perform melt extrusion. Furthermore, it is preferable to select the type and molecular weight of the hot-melt polyolefin B1, the type and molecular weight of the copolymer B2, and other resins B3 to ensure that the melt viscosity of the hot-melt layer is appropriate.

[0120] The operating temperature (melting temperature) of the extruder used as the heat-welding layer, relative to the melting point T of the heat-welding polyolefin B1. mB1 T is preferred mB1 +20℃~T mB1 +120℃, more preferably T mB1 +50℃~T mB1 +100℃.

[0121] The discharge rate of the molten material from the extruder of the heat-welding layer is appropriately determined based on the thickness ratio relative to the substrate layer, the thickness of the laminate, the linear velocity, etc.

[0122] [roll]

[0123] The roll of the present invention is formed by winding the heat-welding laminated film as described above along its length. That is, the heat-welding laminated film of the present invention is preferably manufactured continuously.

[0124] [use]

[0125] The heat-bonding laminated film of the present invention can be used to thermally bond various substrates. Examples of substrates include various metals, various resins, fiber-reinforced resins containing glass fibers, ceramics, etc. Examples of substrate shapes include sheets, films, plates, and three-dimensional shapes having planar portions and curved portions formed by bending planar portions.

[0126] Thermal bonding of the thermoplastic laminated film is performed above the temperature at which the thermoplastic layer softens. Furthermore, when thermal bonding is performed at temperatures where the substrate layer undergoes thermal deformation, it is also possible to thermally bond substrates with more complex surface shapes.

[0127] Example

[0128] The following examples and comparative examples illustrate the present invention in more detail. It should be noted that in the present invention, physical properties are measured or evaluated using the following methods. Unless otherwise specified, "parts" refers to "parts by mass" and "%" refers to "% by mass".

[0129] (1) The thickness of the film and each layer, and the layer thickness ratio

[0130] 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 photographs were taken at an appropriate magnification with the total film thickness as one field of view. Based on the images, the thickness of each layer was measured using a scale. The thickness of the cross-section samples at three independently prepared points was measured, and the average value was taken as the layer thickness of the laminated film. In addition, the layer thickness ratio tA / tB was calculated from this layer thickness.

[0131] (2-1) Melting point

[0132] Take 10 mg of resin sample and perform DSC analysis using a DSC apparatus (TA Instruments Co., Ltd., Q100) at a heating rate of 10 °C / min. Calculate the melting point by defining the peak of the endothermic peak from the obtained graph.

[0133] (2-2) Melting point T of heat-melting polyolefin B1 mB1

[0134] The melting peak temperature of the hot-melt polyolefin B1, as determined by DSC in the same manner as described in (2-1) above, is taken as the melting point T. mB1 In cases with multiple melting peak temperatures, the value is set to the midpoint between the lowest and highest values.

[0135] (3) Film thickness deformation rate of layer A

[0136] The obtained heat-fused laminated film was cut into 10mm × 10mm pieces. With 30 pieces stacked, it was placed in a compression creep testing machine (A&D Corporation, CP6-L-250) and tested at 3MPa and 160℃ (melting point T). mB1 Under conditions of (130℃) + 30℃, a load was applied along the film thickness direction for 10 minutes. After adjusting the environmental conditions, the final loading time of a weight equivalent to 3 MPa was set to 0 minutes, and a 10-minute measurement was performed. For the sample after the load application treatment, the thickness of layer A was measured using the method described in (1) above, the displacement relative to the initial film thickness was calculated, and the film thickness deformation rate of layer A was calculated using the following formula.

[0137] Film thickness deformation rate (%) = (Initial film thickness - Post-treatment film thickness) / Initial film thickness × 100

[0138] (4) In-plane deformation rate

[0139] Samples were taken in 200mm × 200mm sections parallel to the length (MD) and width (TD) directions, and markings were made in the length (MD) and width (TD) directions (marking distance: 100mm). Then, the samples were heated without tension at a temperature set to 160℃ (melting point T). mB1 The sample was subjected to heat treatment for 30 seconds in a constant temperature bath of (130℃) + 30℃. The distance between the puncture points was measured. Based on the distance between the puncture points before heat treatment, the heat deformation rate (%) at 160℃ in the length direction (MD) and width direction (TD) was calculated from the change in the distance between the puncture points.

[0140] (5) Fit

[0141] (5-1) Initial tightness

[0142] SUS316 was used as the substrate to evaluate adhesion. For specimen preparation, a press was used to sandwich the resulting heat-bonding laminated film between two 0.1mm thick SUS316 sheets cut to 150mm x 150mm. The film was then bonded at 160°C with a pressure of 5MPa for 1 minute. This molded sample was cut into 10mm wide and 100mm long pieces to serve as specimen pieces. Holding the SUS316 substrate to be tested at one end, a tensile testing machine (ORIENTEC TENSILON UCT-100 model) was used to peel the specimen piece 180° at a peel speed of 100mm / min according to JIS-C2151. The test was performed five times, and the average of the maximum values ​​was taken as the peel force. Evaluation was conducted according to the following criteria.

[0143] A: Peeling force is above 10N

[0144] B: Peel strength is 3N or higher and less than 10N

[0145] C: Peeling force less than 3N

[0146] It should be noted that, under the evaluation results of B and C above, peeling occurred between layers A and B.

[0147] (5-2) Durability of sealing under humid and hot conditions (121℃×48 hours)

[0148] The sample obtained by immersing the SUS316 adhesive sample (10 mm wide and 100 mm long) prepared in (5-1) above in water at 121°C for 48 hours, leaving it at room temperature for 24 hours and drying it is performed in the same manner as (5-1) above, and evaluated according to the following criteria.

[0149] A: Peeling force is above 10N

[0150] B: Peel strength is 3N or higher and less than 10N

[0151] C: Peeling force less than 3N

[0152] It should be noted that, under the evaluation results of B and C above, peeling occurred between layers A and B.

[0153] (6) Extraction amount of low molecular weight components

[0154] Acetone was evaporated / cooled in a 90°C water bath for 2 hours using a Soxhlet extraction method to extract the dissolved components. The resulting solution was then used to confirm the low molecular weight components with a number average molecular weight below 1000 using an apparatus (Waters e2695). The extraction yield (mass%) of the low molecular weight components was determined from the mass of the sample.

[0155] [Manufacturing Example 1]

[0156] The homopolymer PMP (melting point 242°C) of 4-methyl-1-pentene is prepared as follows.

[0157] In a 1-liter polymerization container that had been fully purged with nitrogen, 400 ml of 4-methyl-1-pentene, 300 ml of hydrogen, 0.5 mmol of triethylaluminum, and 1.0 mmol of titanium(III) chloride were added, and the container was maintained at 60°C. After polymerization for 1 hour, the powder was removed from the container, filtered, washed with hexane, and dried overnight at 80°C under reduced pressure to obtain a polymer yield of 113.9 g.

[0158] [Example 1]

[0159] The mixture, comprising 100% by mass of polymethylpentene (TPX) (manufactured by Mitsui Chemicals, DX845, a copolymer of 4-methyl-1-pentene with a carbon 10 α-olefin of several mol% molar percentages, melting point 233°C) as polymer A1 for forming the substrate layer (layer A), was fed into an extruder and melt-blended at a melt temperature of 280°C. Additionally, modified polyolefin resin (manufactured by Toyobo Co., Ltd., HARDLEN M100, melting peak temperatures 110°C, 130°C, and 150°C, melting point T) was used as the heat-melting polyolefin B1 for forming the heat-melting layer (layer B). mB1 The mixture of 80% by mass of a copolymer (containing 1% by mass of anhydride and 0.3% by mass of low molecular weight components) and 20% by mass of a 4-methyl-1-pentene copolymer (Mitsui Chemicals Co., Ltd., EP1013, 85 mol% of 4-methyl-1-pentene and 15 mol% of α-olefin with 10 carbon atoms) as copolymer B2 in granular form was fed into an extruder and melt-blended at a melting temperature of 230°C.

[0160] Each die slot is configured with a layer structure of B / A / B layers, and co-extrusion is performed with each layer in direct contact. The layers are then cooled and cured on a casting drum with a surface temperature set at 60°C to produce an unstretched film. At this time, the discharge rate is controlled during co-extrusion to ensure that the thickness composition ratio of the unstretched film is 35 / 95 / 35.

[0161] The unstretched film was wound into a roll to obtain a roll of thermally bondable laminated film. The properties of the obtained thermally bondable laminated film are summarized in Table 1.

[0162] [Example 2]

[0163] In Example 1, the ratio of the heat-melting polyolefin B1 and copolymer B2 used to form layer B was changed to 50% by mass and 50% by mass, respectively. Otherwise, rolls of heat-melting laminated films were obtained in the same manner as in Example 1. The properties of the obtained heat-melting laminated films are summarized in Table 1.

[0164] [Example 3]

[0165] In Example 1, a mixture comprising 80% by mass of polymethylpentene (manufactured by Mitsui Chemicals, DX845) as polymer A1 for forming layer A and 20% by mass of 4-methyl-1-pentene copolymer (manufactured by Mitsui Chemicals, EP1013) as other resin A2 was fed into an extruder in granular form. Otherwise, a roll of heat-fused laminated film was obtained in the same manner as in Example 1. The properties of the obtained heat-fused laminated film are summarized in Table 1.

[0166] [Example 4]

[0167] In Example 1, a heat-fused laminated film with a thickness of 268 μm was obtained by changing the discharge amount of layer B / layer A / layer B. Otherwise, a roll of the heat-fused laminated film was obtained in the same manner as in Example 1. The characteristics of the obtained heat-fused laminated films are summarized in Table 1.

[0168] [Example 5]

[0169] In Example 1, a roll of heat-weldable laminated film was obtained in the same manner as in Example 1, except that it contained 100% by mass of a homopolymer PMP (melting point 242°C) of polymethylpentene obtained in Manufacturing Example 1, which was used as polymer A1 for forming layer A. The properties of the obtained heat-weldable laminated film are summarized in Table 1.

[0170] [Example 6]

[0171] In Example 1, a composition comprising 75% by mass of a homopolymer PMP of polymethylpentene obtained in Manufacturing Example 1 as polymer A1 for forming layer A, and 25% by mass of a modified polyolefin resin (manufactured by Toyobo Co., Ltd., HARDLEN M100) as other resin A2, was mixed in granular form and fed into an extruder. Otherwise, a roll of heat-melt laminated film was obtained in the same manner as in Example 1. The characteristics of the obtained heat-melt laminated film are summarized in Table 1.

[0172] [Example 7]

[0173] In Example 1, a roll of heat-melting laminated film was obtained using a composition comprising 80% by mass of a modified polyolefin resin (manufactured by Toyobo Co., Ltd., HARDLEN M100) as the heat-melting polyolefin B1 for forming layer B, and 20% by mass of a 4-methyl-1-pentene copolymer (manufactured by Mitsui Chemicals Co., Ltd., EP1001, 72 mol% 4-methyl-1-pentene, 28 mol% α-olefin, no melting point) as copolymer B2. Otherwise, a roll of heat-melting laminated film was obtained in the same manner as in Example 1. The properties of the obtained heat-melting laminated film are summarized in Table 1.

[0174] [Example 8]

[0175] In Example 5, the ratio of the heat-melting polyolefin B1 and copolymer B2 used to form layer B was changed to 95% by mass and 5% by mass, respectively. The discharge rate of layer B / layer A / layer B was also varied to obtain a heat-melting laminated film with a thickness of 268 μm. Otherwise, rolls of the heat-melting laminated film were obtained in the same manner as in Example 5. The properties of the obtained heat-melting laminated films are summarized in Table 1.

[0176] [Comparative Example 1]

[0177] In Example 1, copolymer B2 for forming layer B was not used. Instead, a composition containing 100% by mass of a modified polyolefin resin (manufactured by Toyobo Co., Ltd., HARDLEN M100) as the heat-melting polyolefin B1 was used. Additionally, a composition containing 30% by mass of polymethylpentene (manufactured by Mitsui Chemicals Co., Ltd., DX845) as the polymer A1 for forming layer A and 70% by mass of polypropylene resin (manufactured by Sumitomo Chemical Co., Ltd., FS2011DG3) as the other resin A2 was used. The mixture was fed into an extruder in granular form, and a roll of heat-melting laminated film was obtained in the same manner as in Example 1. The characteristics of the obtained heat-melting laminated film are summarized in Table 1. Furthermore, due to the extremely high in-plane deformation rate, it was impossible to measure the in-plane deformation rate.

[0178] [Comparative Example 2]

[0179] In Example 1, copolymer B2, used to form layer B, was not used. Instead, a composition comprising 100% by mass of a modified polyolefin resin (manufactured by Toyobo Co., Ltd., HARDLEN M100) as the heat-melting polyolefin B1 was used. Otherwise, a roll of heat-melting laminated film was obtained in the same manner as in Example 1. The characteristics of the obtained heat-melting laminated film are summarized in Table 1. It should be noted that when measuring the durability of the seal under humid and hot conditions, peeling occurred between layer B and layer A, therefore, the durability of the seal could not be measured.

[0180] [Comparative Example 3]

[0181] In Example 1, a roll of heat-melt laminated film was obtained using a composition comprising 80% by mass of a modified polyolefin resin (manufactured by Toyobo Co., Ltd., HARDLEN M100) as the heat-melt polyolefin B1 for forming layer B and 20% by mass of polymethylpentene (TPX) (manufactured by Mitsui Chemicals Co., Ltd., DX845) replacing copolymer B2. The characteristics of the obtained heat-melt laminated film are summarized in Table 1. It should be noted that when measuring the durability of the seal under humid and hot conditions, peeling occurred between layer B and layer A, therefore the durability of the seal could not be measured.

[0182] [Comparative Example 4]

[0183] A film for a substrate layer formed from layer A and a film for a heat-welding layer formed from layer B are manufactured separately. Specifically, a composition containing 100% by mass of polymethylpentene (TPX) (manufactured by Mitsui Chemicals, Ltd., DX845) as polymer A1 for forming the substrate layer (layer A) is fed into an extruder and melt-mixed at a melt temperature of 280°C. This is extruded from a die and cooled and solidified on a casting drum with a surface temperature set to 60°C to obtain an unstretched film with a thickness of 95 μm. This film is then rolled into a roll to obtain a roll of the substrate layer film.

[0184] In addition, 50% by mass of a modified polyolefin resin (manufactured by Toyobo Co., Ltd., HARDLEN M100) as the heat-melting polyolefin B1 used to form the heat-melting layer, i.e., layer B, and 50% by mass of a 4-methyl-1-pentene copolymer (manufactured by Mitsui Chemicals Co., Ltd., EP1013) as copolymer B2 were mixed in granular form and fed into an extruder for melt mixing at a melt temperature of 230°C. The mixture was then extruded from a die and cooled and cured on a casting drum with a surface temperature set at 60°C to obtain an unstretched film with a thickness of 35 μm. This film was then rolled into a roll to obtain a roll of the heat-melting layer film.

[0185] A roll of substrate film is unwound, and rolls of heat-fused laminated films are unwound from both sides. A heating roller wound with Teflon tubing is set to 180°C, and lamination is performed while the film is being held in place, resulting in a roll of heat-fused laminated film formed from layer B / layer A / layer B. The characteristics of the heat-fused laminated film obtained by this processing method are summarized in Table 1. It should be noted that due to the peeling between layer B and layer A, initial adhesion and durable adhesion cannot be measured.

[0186] [Table 1]

[0187]

[0188] As shown in Table 1, in Examples 1 to 8, heat-weld laminated films with high adhesion at the lamination interface under initial and humid conditions and good bonding state during heat fusion can be obtained.

[0189] In contrast, in Comparative Example 1, where the content of 4-methyl-1-pentene polymer in the substrate layer is low, the film thickness deformation rate of the substrate layer is extremely high, the in-plane deformation rate of the heat-welding laminate is also large, and the bonding condition during heat fusion is deteriorated. It should be noted that in Comparative Example 1, by containing a large amount of polypropylene resin in the substrate layer, the adhesion between the substrate layer and the heat-welding layer is improved.

[0190] Furthermore, in Comparative Example 2, where the heat-melting layer did not contain the 4-methyl-1-pentene copolymer, and in Comparative Example 3, where a copolymer with an excessively high molar percentage of 4-methyl-1-pentene was used, the adhesion at the lamination interface decreased initially and under humid and hot conditions. Moreover, in Comparative Example 4, where the substrate layer and the heat-melting layer were heat-laminated, the adhesion at the lamination interface also decreased significantly initially and under humid and hot conditions.

[0191] Industrial availability

[0192] The heat-weldable laminated film of the present invention does not cause delamination between layers of various planar or thin-film substrates, including metals, glass, and resins, whether or not they contain fiber-based reinforcements. It has excellent adhesion and can suppress bonding defects by keeping the film thickness deformation rate of the substrate layer that can withstand the heat during bonding and molding at a small level. Therefore, it has high potential for industrial application.

Claims

1. A heat-weldable laminated film, comprising layers B, A, and B stacked sequentially by co-extrusion. The A layer contains 100-70% by mass of polymer A1, wherein polymer A1 has structural units derived from 4-methyl-1-pentene at a rate of 90 mol% to 100 mol% relative to all structural units. The B layer contains 99-30% by mass of a heat-melting polyolefin B1 and 1-70% by mass of a copolymer B2, wherein the copolymer B2 has 60 mol% and 89 mol% of structural units derived from 4-methyl-1-pentene and 11 mol% and 40 mol% of structural units derived from α-olefins other than 4-methyl-1-pentene, having 2 or more and 20 or fewer carbon atoms. The hot-melt polyolefin B1 is a modified polyolefin resin modified with acid anhydride, the acid anhydride content of the hot-melt polyolefin B1 is 0.1~3% by mass, and the amount of low molecular weight components with a number average molecular weight of less than 1000 based on acetone extracted from the hot-melt polyolefin B1 is less than 1% by mass.

2. The heat-weldable laminated film according to claim 1, wherein, The melting peak temperature of the hot-melt polyolefin B1, determined by DSC, is set as the melting point T. mB1 At that time, in T mB1 The film thickness deformation rate of layer A under a 3MPa load at +30℃ for 10 minutes is less than 5%, wherein the melting peak temperature is the intermediate value between the lowest and highest values ​​when multiple melting peak temperatures are present. Film thickness deformation rate (%) = (initial film thickness - processed film thickness) / initial film thickness × 100.

3. The heat-weldable laminated film according to claim 1, wherein, The polymer A1 has 100 mol% of structural units derived from 4-methyl-1-pentene relative to all structural units.

4. The heat-weldable laminated film according to claim 1, wherein, Layer A contains 100% by mass of the polymer A1.

5. The heat-weldable laminated film according to claim 1, wherein, When the film thickness of layer A is set to tA and the film thickness of layer B is set to tB, the following equation (1) is satisfied. 2≤tA / tB≤5 (1).

6. The heat-weldable laminated film according to claim 1, wherein, The α-olefin having 2 or more but less than 20 carbon atoms is at least one of ethylene, propylene, 1-butene, 1-hexene, 1-octene, 1-decene, 1-tetradecene, and 1-octadecene.

7. The heat-weldable laminated film according to claim 2, wherein, Melting point T mB1 At a temperature of +30℃, the in-plane deformation rate in the length direction (MD) and width direction (TD) is less than 4%. The in-plane deformation rate is calculated as follows: Samples are taken parallel to the length direction MD and the width direction TD, and markings are made in the length direction MD and the width direction TD, with a distance of 100 mm between the markings. The samples are then taken without tension and placed in a position designated as T. mB1 The treatment was carried out in a constant temperature bath at +30℃, and the distance between the puncture points was measured. The distance between the puncture points before heat treatment was used as a reference, and the result was calculated from the change in the distance between the puncture points.

8. The heat-weldable laminated film according to claim 1, wherein, According to JIS-C2151, the peel force when peeling the SUS316 substrate at a peel speed of 100 mm / min at a 180° angle is 3N or more.

9. A roll formed by winding the thermally bondable laminated film of any one of claims 1 to 8 along its length.

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