A stacked object composed of bidirectional polyester film and bidirectional polyamide film.

Abstract

Invention details;

Description

Laminate containing biaxially oriented polyester film and biaxially oriented polyamide film

[0001] The present invention relates to a laminate comprising a biaxially oriented polyester film and a biaxially oriented polyamide film, and particularly to a laminate suitable for use in cold forming applications.

[0002] In recent years, laminated lithium-ion battery exterior materials and press-through packs have been obtained by cold forming laminates made of resin films and metal foils. The laminates used for cold forming generally have a structure such as polyethylene terephthalate film / biaxially oriented nylon film / aluminum foil / polypropylene film (see, for example, Patent Document 1).

[0003] In addition, with regard to pharmaceutical packaging, there is an increasing need for packaging forms that use metal foil, such as aluminum, to prevent deterioration of the contents, and there is a demand for improved formability of metal foil to match the shape of the contents.

[0004] One factor that affects moldability during cold forming is the flexibility of the resin film. If the resin film has low flexibility, a strong load is applied during elongation during cold forming, which may result in pinholes or delamination. Conversely, if the resin film has too high flexibility, the effect of protecting the laminate containing the metal foil as a substrate is reduced, and the physical properties of the resulting laminate are reduced. For this reason, it is important that the resin film has flexibility that is neither too high nor too low.

[0005] As a means for solving these problems, for example, Patent Document 2 discloses that the base material layer is made of a laminate in which at least a base material layer, an adhesive layer, a metal layer, and a sealant layer are laminated in this order, and that good moldability can be obtained by setting the sum (A+B) of the value A of the stress at 50% elongation / stress at 5% elongation in the MD direction and the value B of the stress at 50% elongation / stress at 5% elongation in the TD direction within a specific range.

[0006] On the other hand, the cold forming described above is prone to problems with springback, a phenomenon in which a portion of the formed product returns from its post-forming shape to its pre-forming shape after drawing. This springback can lead to problems such as insufficient dimensional accuracy of the shape after drawing. Furthermore, because the surrounding areas are pulled strongly during forming, warpage can occur as the surrounding base material layer tries to return to its original state after forming, potentially reducing the yield in post-processing.

[0007] In contrast to this, as described in Patent Document 2 mentioned above, merely controlling the F5 value and F50 value of the film improves the forming depth, but this is insufficient to improve the deterioration of dimensional accuracy due to springback after forming and the warpage resistance after forming.

[0008] JP 2008-053133 A International Publication No. 2015-125806 A

[0009] The present invention has been made in view of the problems of the prior art. An object of the present invention is to provide a laminate containing a biaxially oriented polyester film and a biaxially oriented polyamide film, which not only has excellent cold formability but also suppresses a decrease in dimensional accuracy after forming due to springback and has excellent warpage resistance.

[0010] As a result of extensive research, the inventors have discovered that by selecting a specific range of stretching conditions and controlling the mechanical properties of the film within a predetermined range, it is possible to achieve excellent cold formability and suppress springback and curling after forming, thereby arriving at the present invention.

[0011] That is, the present invention has the following configuration: [Item 1] A laminate including a substrate layer, an intermediate layer, a metal foil, and a sealant layer, wherein the substrate layer is a biaxially oriented polyester film that satisfies the following (a) to (c), and the intermediate layer is a biaxially oriented polyamide film that satisfies the following (d) to (f): (a) A puncture strength of 0.45 N / μm or more and 0.80 N / μm or less. (b) A heat shrinkage rate at 150°C is 2.5% or less in both the MD and TD directions. (c) In a tensile stress relaxation test at 25°C, the stress attenuation rate shown by the following formula (1) is 15.0% or more in both the MD and TD directions. Formula (1) Stress attenuation rate (%) = 100 × (σ0 - σ1) / σ0 Here, σ0 represents the tensile stress value immediately after applying a tensile force to the film at a pulling rate of 200 mm / min to apply the 50% tensile strain, and σ1 represents the tensile stress value when the 50% tensile strain is maintained for 2 seconds. (d) A puncture strength measured in accordance with JIS Z 7102 is 0.5 N / μm or more and 1.0 N / μm or less. (e) the heat shrinkage rate at 160°C is 3.0% or less in both the MD direction and the TD direction; and (f) in a tensile stress relaxation test at 25°C, the stress decay rate represented by the formula (1) is 12.0% or more in both the MD direction and the TD direction. [Item 2] The laminate according to Item 1, wherein the base layer further satisfies the following (g): (g) When the stresses at 3% elongation in the MD direction and TD direction of the film at 25°C are X(MD) and X(TD), respectively, the stresses at 30% elongation in the MD direction and TD direction are Y(MD) and Y(TD), respectively, and the values ​​of Y(MD) / X(MD) and Y(MD) / X(MD) are Z(MD) and Z(TD), respectively, the laminate satisfies all of the following formulas (2) to (5): Formula (2) 125 MPa≦Y(MD)≦155 MPa Formula (3) 140 MPa≦Y(TD)≦190 MPa Formula (4) 1.3≦Z(MD)≦1.6 Formula (5) 1.7≦Z(TD)≦2.2 [Item 3] The laminate according to item 1 or 2, further satisfying the following (h):(h) When the stresses at 3% elongation in the MD direction and TD direction of the film at 25°C are X(MD) and X(TD), respectively, the stresses at 30% elongation in the MD direction and TD direction and the values ​​of Y(MD) and Y(TD), respectively, and the values ​​of Y(MD) / X(MD) and Y(MD) / X(MD), respectively, are Z(MD) and Z(TD), the following formulas (6) to (9) are satisfied: Formula (6) 100 MPa≦Y(MD)≦150 MPa Formula (7) 110 MPa≦Y(TD)≦200 MPa Formula (8) 1.4≦Z(MD)≦2.2 Formula (9) 2.5≦Z(TD)≦3.5 [Item 4] The laminate according to any one of Items 1 to 3, further comprising a printed layer. [Item 5] A battery packaging material comprising the laminate according to any one of Items 1 to 4.

[0012] By using the laminate of the present invention, the metal foil can appropriately conform to the shape of the mold during molding, thereby suppressing not only the occurrence of pinholes and cracks, but also springback and warpage after molding. The excellent dimensional accuracy during molding also contributes to improved productivity.

[0013] FIG. 2 is a schematic diagram showing a method of multistage stretching in the TD direction in the film production process.

[0014] The present invention will be described in detail below.

[0015] [Substrate Layer] The substrate layer in the present invention is composed of a biaxially oriented polyester film. The biaxially oriented polyester film is a film formed from a polyester resin composition containing terephthalic acid as a dicarboxylic acid component and ethylene glycol as a diol component as main components. Here, "containing as a main component" means that the content of the component in the polyester resin composition is 80 mol% or more, preferably 90 mol% or more, more preferably 95 mol% or more, and most preferably 97 mol% or more, based on 100 mol% of all components of the polyester resin.

[0016] These polyester resins may also be copolymerized with other components, provided that the objectives of the present invention are not impaired. Specific examples of copolymerization components include dicarboxylic acid components such as isophthalic acid, naphthalenedicarboxylic acid, 4,4-diphenyldicarboxylic acid, adipic acid, sebacic acid, and ester-forming derivatives thereof. Examples of diol components include diethylene glycol, hexamethylene glycol, neopentyl glycol, and cyclohexanedimethanol. Other examples include polyoxyalkylene glycols such as polyethylene glycol and polypropylene glycol. The copolymerization amount is preferably 10 mol % or less, more preferably 5 mol % or less, and most preferably 3 mol % or less, per constituent repeating unit.

[0017] The polyester resin composition may contain a single polyester resin or a plurality of polyester resins, or may contain a resin other than polyester resins.

[0018] The intrinsic viscosity of the polyester resin composition is preferably in the range of 0.50 to 0.90 dl / g, more preferably in the range of 0.55 to 0.80 dl / g, from the viewpoints of film-forming properties and re-recovery properties.

[0019] The polyester resin composition may contain, in addition to the polyester resin, conventionally known additives such as a lubricant, a stabilizer, a colorant, an antioxidant, an antistatic agent, and an ultraviolet absorber.

[0020] For example, the lubricant can adjust the dynamic friction coefficient of the film, and examples thereof include inorganic lubricants such as silica, calcium carbonate, alumina, and organic lubricants. As the inorganic lubricant, silica and calcium carbonate are preferred, and among them, porous silica is most preferred from the viewpoint of achieving both transparency and lubricity.

[0021] The lower limit of the lubricant content in the biaxially oriented polyester film of the present invention is preferably 400 ppm by mass, more preferably 600 ppm by mass. By setting it to 500 ppm by mass or more, the slipperiness of the film can be improved. The upper limit of the lubricant content is preferably 1500 ppm by mass, more preferably 1200 ppm by mass. By setting it to 1500 ppm by mass or less, the transparency of the film can be improved.

[0022] The method for obtaining a biaxially oriented polyester film is not particularly limited, and can be appropriately selected from methods such as the T-die method and inflation method. A typical production process for the T-die method is described below. The T-die method includes: (1) a step of melt-extruding a polyester resin composition into a sheet and cooling it on a cooling roll to form an unstretched sheet; (2) a stretching step of stretching the formed unstretched sheet in the MD direction (longitudinal direction) and the TD direction (transverse direction) perpendicular to the MD direction; (3) a heat-setting step of heating and crystallizing the film after the stretching; (4) a heat-relaxing step (sometimes referred to as a relaxation step) of removing residual strain in the heat-set film; and (5) a cooling step of cooling the film after the heat-relaxing step.

[0023] The substrate layer of the present invention may have a single layer structure or a laminate structure of two or more layers. It may also have two, three, four, or five layers. The resin compositions forming each layer may be the same or different.

[0024] The upper limit of the chill roll temperature is preferably 40°C, more preferably 20°C or lower. If the temperature is 40°C or higher, the crystallinity of the molten polyester resin composition does not become too high when it is cooled and solidified, making it easier to stretch, and also suppressing a decrease in transparency due to crystallization. The lower limit of the chill roll temperature is preferably 0°C. If the temperature is 0°C or higher, the effect of suppressing crystallization when the molten polyester resin composition is cooled and solidified can be fully exerted. Furthermore, when the chill roll temperature is in the above range, it is preferable to reduce the humidity of the environment near the chill roll to prevent condensation.

[0025] The thickness of the unstretched sheet is preferably in the range of 15 to 2500 μm, more preferably 600 μm or less, and most preferably 400 μm or less.

[0026] Next, the stretching step will be described. The stretching method can be simultaneous biaxial stretching or sequential biaxial stretching. The following description will be given taking sequential biaxial stretching as an example.

[0027] The lower limit of the stretching ratio in the MD direction is preferably 2.5 times, more preferably 2.8 times, and particularly preferably 3.1 times. When the stretching ratio is 2.5 times or more, not only the mechanical strength of the film is improved, but also thickness unevenness is improved, leading to improved winding quality when formed into a roll. The upper limit of the stretching ratio in the MD direction is preferably 5.0 times, more preferably 4.5 times, and particularly preferably 4.0 times. By setting the stretching ratio in the MD direction to 5.0 times or less, it is possible to prevent the film from becoming too oriented, thereby preventing large springback and curl after molding.

[0028] The temperature during MD stretching is preferably in the range of 80 to 130°C. If the MD stretching temperature is lower than 80°C, the orientation of the film will be too high, which may result in significant springback and curling after molding. On the other hand, if the MD stretching temperature is higher than 130°C, the orientation in the MD will be low, which may result in reduced moldability.

[0029] As a method for stretching in the MD direction, a method of stretching between multiple heated rolls or a method of stretching while heating with an infrared heater or the like is used. The method of stretching while heating with an infrared heater or the like is preferred because it is easy to obtain high temperatures, local heating is easy, and scratches caused by the rolls can be reduced. On the other hand, when using a method of stretching between multiple heated rolls, a multi-stage stretching method between multiple rolls is preferred. By using a multi-stage stretching method between multiple rolls, it is possible to suppress an increase in MD orientation even when stretching at a high ratio, and it is possible to suppress springback and curling after molding. The number of rolls used in multi-stage stretching is preferably 2 or more, more preferably 3 or more.

[0030] In the stretching process, it is preferable to include a relaxation step in the MD direction (hereinafter also referred to as MD relaxation) between the MD stretching step and the subsequent TD stretching step. The lower limit of the MD relaxation rate is preferably 1%, more preferably 3%, and particularly preferably 5%. If it is 1% or more, the amorphous components in the film are relaxed, which can reduce the stretching stress in the subsequent TD stretching step, thereby preventing the film from becoming too oriented, thereby suppressing springback and curling after molding. The upper limit of the MD relaxation rate is preferably 10%, more preferably 8%, and particularly preferably 6%. If it is 10% or less, wrinkles due to shrinkage can be suppressed, improving the quality of the film and suppressing a decrease in mechanical strength due to orientation relaxation. The MD relaxation method is not particularly limited, but an example is a method in which a film is heated with a hot air heater and then relaxed using the speed difference between rolls.

[0031] The lower limit of the TD stretching temperature is preferably 90°C, more preferably 100°C, and particularly preferably 110°C. If the temperature is 90°C or higher, the stretching stress can be reduced, thereby suppressing springback and curling after molding. The upper limit of the TD stretching temperature is preferably 140°C, more preferably 130°C, and particularly preferably 120°C. If the TD stretching temperature exceeds 140°C, not only will film formability decrease, but the orientation of the obtained film in the TD direction will be weak, which may result in a decrease in formability.

[0032] The lower limit of the stretching ratio in the TD direction is preferably 2.5 times, more preferably 3.0 times, and particularly preferably 3.5 times. When it is 2.5 times or more, not only is the mechanical strength and thickness unevenness of the film improved, but also formability is improved. The upper limit of the stretching ratio in the TD direction is preferably 5.0 times, more preferably 4.5 times, and particularly preferably 4.0 times. By setting it to 5.0 times or less, an increase in orientation in the TD direction can be suppressed, and the occurrence of springback and curling after molding can be suppressed.

[0033] As for the TD stretching pattern, in addition to the commonly used linear stretching pattern in which the stretch ratio increases linearly, multistage stretching can be preferably used. Multistage stretching involves performing two or more stretching steps in comparison with the usual one-stage stretching, i.e., linear stretching pattern, as shown in an example in Figure 1, and can reduce the stretching stress applied during TD stretching. As a result, even with the same stretch ratio, excessively high orientation in the TD can be prevented, and springback and curling after forming can be suppressed.

[0034] The multistage stretching in the TD direction is preferably two to five stage stretching. Multistage stretching allows the stretching stress to be changed by changing the temperature of each stretching step, which is preferable because it allows the stretching stress during TD stretching to be reduced. Two or more stage stretching can reduce the stretching stress, preventing excessively high TD orientation even at the same stretch ratio, thereby suppressing springback and curling after forming. Five or fewer stage stretching can prevent the equipment from becoming too large. In multistage stretching, a temperature pattern is preferably used in which the temperature is lowered from the first stage to the final stage, with a temperature difference of 2°C or more between each stage. Furthermore, when multistage stretching is performed, a constant length zone can be appropriately provided after each stretching stage. By providing a constant length zone after each stretching stage, the internal stress generated during stretching can be alleviated in the constant length zone, thereby further reducing the stretching stress when the next stretching is performed.This prevents the TD orientation from becoming too high even with the same stretching ratio, and suppresses springback and curling after molding.

[0035] In the heat setting step, the lower limit of the heat setting temperature is preferably 170°C, more preferably 180°C, and particularly preferably 190°C. If the temperature is 170°C or higher, the heat shrinkage rate can be reduced. The upper limit of the heat setting temperature is preferably 230°C, more preferably 220°C, and particularly preferably 210°C. If the temperature is 230°C or lower, the decrease in mechanical strength due to the brittleness of the biaxially oriented polyester film can be suppressed.

[0036] In the heat-relaxing step, the lower limit of the relaxation rate in the TD direction is preferably 0.5%, more preferably 1.0%, and particularly preferably 2.0%. If it is 0.5% or more, the thermal shrinkage rate in the TD direction can be kept low. The upper limit of the relaxation rate in the TD direction is preferably 10%, more preferably 8%, and particularly preferably 6%. If it is 10% or less, the occurrence of slack and the like can be prevented, and flatness can be improved.

[0037] [Configuration and Properties of Base Layer] The lower limit of the thickness of the base layer of the present invention is preferably 5 μm, more preferably 10 μm. By setting the thickness to 5 μm or more, good mechanical properties and moldability can be obtained. The upper limit of the thickness of the base layer is preferably 100 μm, more preferably 70 μm, and particularly preferably 40 μm.

[0038] The lower limit of the puncture strength of the base layer of the present invention is preferably 0.45 N / μm, and more preferably 0.50 N / μm. When the puncture strength is 0.45 N / μm or more, good formability can be obtained. The upper limit of the puncture strength of the base layer is 0.80 N / μm. When the puncture strength exceeds 0.80 N / μm, the formability improvement effect saturates. Here, the puncture strength (unit: N / μm) in the present invention refers to the strength (unit: N) when a needle with a tip radius of 0.5 mm punctures a film at a puncture speed of 50 mm / min and penetrates the film, divided by the thickness of the film (unit: μm).

[0039] The lower limit of the heat shrinkage rate in the MD and TD of the base layer of the present invention is preferably 0.1%, more preferably 0.2%, and particularly preferably 0.3%. The upper limit of the heat shrinkage rate in the MD and TD is preferably 2.5%, more preferably 2.0%, and particularly preferably 1.8%. By keeping it 2.5% or less, dimensional changes when heated in the secondary processing step can be suppressed, and the occurrence of wrinkles can be reduced.

[0040] The thickness variation in the TD direction of the base layer of the present invention is preferably 18% or less, more preferably 16% or less, and even more preferably 14% or less. When it is 18% or less, the winding quality when made into a roll is good.

[0041] The haze of the substrate layer of the present invention is preferably 5.0% or less, more preferably 3.0% or less, and even more preferably 2.5% or less. By making it 5.0% or less, the print looks beautiful, which is preferable.

[0042] Next, springback during molding will be described. When molding for applications such as battery exteriors and pharmaceutical packaging, a molded body is produced by pressing a film into a mold of a predetermined shape, holding the pressed-in state for a certain period of time, and then lifting the mold. However, if the mold is lifted without the internal stress in the film being sufficiently relaxed during the holding time, a force acts on the film to return to its original shape, increasing springback, which may result in a decrease in the dimensional accuracy of the molded body. The present inventors have found that the springback can be reduced by setting the stress reduction rate after 2 seconds of holding within a specific range in a tensile stress relaxation test of the obtained biaxially oriented polyester film.

[0043] In a tensile stress relaxation test at 25°C, the base layer of the present invention preferably has a stress decay rate, as shown by the following formula (1), of 15% or more, and more preferably 16% or more, in both the MD and TD directions: Stress decay rate after 2-second hold (%) = 100 × (σ0 - σ1) / σ0 Formula (1) Here, σ0 represents the tensile stress value of the film immediately after applying a tensile force to the film at a pulling rate of 200 mm / min to apply the 50% tensile strain, and σ1 represents the tensile stress value when the 50% tensile strain is held for 2 seconds.

[0044] The base layer of the present invention preferably satisfies the following formulas (2) and (3), where Y(MD) is the stress at 30% elongation in the MD direction of the film (F30 value) and Y(TD) is the stress at 30% elongation in the TD direction of the film at 25°C (F30 value): Formula (2) 125 MPa≦Y(MD)≦155 MPa Formula (3) 140 MPa≦Y(TD)≦190 MPa

[0045] By setting the Y (MD) value to 125 MPa or more, excellent formability can be obtained. On the other hand, by setting the Y (MD) value to 155 MPa or less, the stress of the film after molding can be prevented from becoming too large, and springback and warpage resistance after molding can be reduced, resulting in good formability. Similarly, by setting the Y (TD) value to 140 MPa or more, excellent formability can be obtained. By setting the Y (TD) value to 190 MPa or less, the stress of the film after molding can be prevented from becoming too large, and springback and warpage resistance after molding can be reduced, resulting in good formability.

[0046] The base layer of the present invention preferably satisfies the following formulas (4) and (5), where X(MD) is the stress at 3% elongation in the MD direction of the film (F3 value), X(TD) is the stress at 3% elongation in the TD direction of the film at 25°C (F3 value), Z(MD) is the value of Y(MD) / X(MD), and Z(TD) is the value of Y(TD) / X(TD): Formula (4) 1.3≦Z(MD)≦1.6 Formula (5) 1.7≦Z(TD)≦2.2

[0047] By setting the Z (MD) value to 1.3 or more, excellent formability can be obtained. On the other hand, by setting the Z (MD) value to 1.6 or less, the stress of the film after molding can be prevented from becoming too large, and springback and warpage resistance after molding can be reduced, resulting in good formability. Similarly, by setting the Z (TD) value to 11.7 or more, excellent formability can be obtained. By setting the Z (TD) value to 2.2 or less, the stress of the film after molding can be prevented from becoming too large, and springback and warpage resistance after molding can be reduced, resulting in good formability.

[0048] From the viewpoint of formability, the base layer of the present invention preferably has a dynamic friction coefficient μd with a metal surface of 0.10 or more and 0.50 or less. When the polyester film of the present invention is used for battery exteriors or pharmaceutical packaging, these components are molded by male-female press molding. By setting the dynamic friction coefficient μd between the film and the metal to 0.10 or more and 0.50 or less, smooth molding is possible due to good sliding properties with the press mold. More preferably, it is 0.20 or more and 0.50 or less, and even more preferably, it is 0.25 or more and 0.40 or less. In the present invention, the dynamic friction coefficient with metal refers to the dynamic friction coefficient between any surface of the film and SUS304-#400 mirror-finished material. The dynamic friction coefficient can be controlled by the content of a lubricant added to the film.

[0049] [Intermediate layer] The intermediate layer of the present invention is composed of a biaxially oriented polyamide film. The biaxially oriented polyamide film is preferably formed from a polyamide resin composition containing 60% by mass or more of polyamide 6, more preferably 80% by mass or more of polyamide 6, and even more preferably 90% by mass or more of polyamide 6. By containing 60% by mass or more of polyamide 6, excellent mechanical strength such as impact strength and gas barrier properties can be obtained.

[0050] The polyamide 6 used in the present invention is usually produced by ring-opening polymerization of ε-caprolactam. The polyamide 6 obtained by ring-opening polymerization is usually subjected to removal of lactam monomer with hot water, followed by drying and melt-extrusion in an extruder.

[0051] The relative viscosity of polyamide 6 is preferably 1.8 to 4.5, more preferably 2.6 to 3.2. If the relative viscosity is less than 1.8, the impact strength of the film may be insufficient. If it is greater than 4.5, the load on the extruder may increase, making it difficult to obtain an unstretched film before stretching. The polyamide 6 used in the present invention may be commercially available from Ube Industries, Ltd., BASF, etc. In particular, polyamide 6 commercially available for film use, having the above relative viscosity, a residual lactam monomer content of 1% by mass or less, and being end-blocked or end-modified so that lactam monomers are unlikely to be generated when melted, is preferred.

[0052] As polyamide 6, in addition to polyamide 6 polymerized from commonly used monomers derived from fossil fuels, polyamide 6 chemically recycled from waste polyamide 6 products such as waste plastic products, waste tire rubber, fibers, fishing nets, etc. As a method for obtaining chemically recycled polyamide 6 from waste polyamide 6 products, for example, a method can be used in which used polyamide products are collected, depolymerized to obtain ε-caprolactam, which is then purified, and then polyamide 6 is polymerized.

[0053] In addition, polyamide 6 can be used in combination, which is mechanically recycled waste material generated during the polyamide film manufacturing process. Mechanically recycled polyamide 6 is a raw material obtained by recovering waste material generated during the manufacturing of biaxially oriented polyamide film, such as non-standard, unshippable film and offcuts (edge ​​trims), and pelletizing the recovered material through melt extrusion or compression molding.

[0054] The intermediate layer of the present invention may contain, in addition to the main component polyamide 6, other thermoplastic resins for the purpose of improving stretchability, pinhole resistance, cut resistance, etc. Furthermore, it may contain small amounts of additives such as anti-blocking agents, lubricants, antistatic agents, heat stabilizers, and light resistance agents.

[0055] Examples of thermoplastic resins other than polyamide 6 that can be used in the present invention include homopolymers or copolymers of polyamide-based resins, polyester-based resins, polyolefin-based resins, acrylic-based resins, polycarbonate-based resins, polyvinyl-based resins, and urethane-based resins.

[0056] In one embodiment of the present invention, the biaxially oriented polyamide film may contain polyamide MXD6 and / or polyamide 6I to improve stretchability during film formation. The content of these polyamides is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less, based on the resin composition forming the biaxially oriented polyamide film.

[0057] In one embodiment of the present invention, the biaxially oriented polyamide film may contain a polyamide elastomer, a polyester elastomer, a polyolefin elastomer, or the like in order to improve pinhole resistance.

[0058] In one embodiment of the present invention, the biaxially oriented polyamide film may contain inorganic fine particles such as silica, kaolin, zeolite, etc., or crosslinked polymer fine particles such as acrylic, polystyrene, etc., as an anti-blocking agent or lubricant. Silica fine particles are preferably used in terms of transparency and lubricity.

[0059] In one embodiment of the present invention, the biaxially oriented polyamide film may contain an organic lubricant that reduces surface energy as a lubricant, provided that the lubricant does not cause problems with adhesion or wettability. Examples of organic lubricants include ethylene bisstearic acid amide (EBS). The combined use of the anti-blocking agent and the lubricant is preferred because it simultaneously provides the film with excellent slip properties and transparency.

[0060] The method for obtaining the biaxially oriented polyamide film of the present invention is not particularly limited, and can be appropriately selected from methods such as the T-die method and inflation method. A typical production process for the T-die method is described below. The T-die method includes: (1) a step of melt-extruding a polyamide resin composition into a sheet and cooling it on a cooling roll to form an unstretched sheet; (2) a step of stretching the formed unstretched sheet in the MD direction (longitudinal direction) and the TD direction (transverse direction) perpendicular to the MD direction; (3) a heat-setting step of heating and crystallizing the stretched film; (4) a heat-relaxing step (sometimes referred to as a relaxation step) of removing residual strain in the heat-set film; and (5) a cooling step of cooling the film after heat-relaxing.

[0061] The intermediate layer of the present invention may have a single layer structure or a laminate structure of two or more layers. It may have two, three, four or five layers. The resin compositions forming each layer may be the same or different.

[0062] One embodiment for obtaining a biaxially oriented polyamide film preferably includes a step of pre-stretching an unstretched sheet in the MD direction at a low magnification, and then main-stretching it in the MD direction at a high magnification.

[0063] The MD pre-stretching is preferably carried out in one or two stages. The total stretching ratio obtained by multiplying the respective stretching ratios in the MD pre-stretching is preferably 1.005 times or more and 1.15 times or less. On the other hand, by setting the pre-stretching ratio to 1.15 times or less, the progress of orientation crystallization can be prevented, and the occurrence of breakage during the main stretching or TD stretching due to excessively high stretching stress in the subsequent MD main stretching can be suppressed.

[0064] The MD pre-stretching is preferably performed at a temperature of (Tg + 20°C or higher) to (Tc + 20°C or lower) from the glass transition temperature of the polyamide resin composition (unit: °C). Here, Tg and Tc are values ​​obtained by measuring using the method described in the Examples. By performing the MD pre-stretching at a temperature of (Tg + 20)°C or higher, necking can be prevented and thickness unevenness can be suppressed. Furthermore, by performing stretching at a temperature of (Tc + 20)°C or lower, thermal crystallization can be prevented and breakage in the TD stretching step can be suppressed. A more preferred stretching temperature is (Tg + 30)°C or higher and (Tc + 10)°C or lower. For the MD pre-stretching, known longitudinal stretching methods such as hot roll stretching and infrared radiation stretching can be used.

[0065] The MD main stretching is preferably carried out in two or more stages. The ratio of the first-stage MD main stretching is preferably 1.1 times or more and 2.9 times or less. If the stretching ratio in the first stage of the main longitudinal stretching is too low, the stretching effect cannot be obtained. On the other hand, by setting the first-stage stretching ratio to 2.9 times or less, the progression of oriented crystallization can be prevented.

[0066] The first-stage stretching temperature in the MD main stretching is preferably (Tg + 20)°C or higher and (Tc + 20)°C or lower. If the stretching temperature is lower than (Tg + 20)°C, the stretching stress becomes high and the film is more likely to break during TD stretching, while if the stretching temperature exceeds (Tc + 20)°C, thickness unevenness may become large. More preferably, the temperature is (Tg + 25)°C or higher and (Tc + 10)°C or lower. For the first stage of MD main stretching, a known MD stretching method such as hot roll stretching or infrared radiation stretching can be used.

[0067] The ratio of the MD main stretching in the second and subsequent stages is preferably set so that the total stretching ratio, obtained by multiplying each stretching ratio including the MD pre-stretching ratio, is 2.8 to 5.0 times, more preferably 3.0 to 3.8 times, and even more preferably 3.0 to 3.6 times. If it is less than 2.8 times, the variation in physical properties in the width direction of the biaxially oriented film will be reduced, but the strength in the longitudinal direction may be reduced. If the total longitudinal stretching ratio is too large, the effect of reducing the variation in physical properties in the width direction of the biaxially oriented film may not be achieved.

[0068] The second-stage stretching temperature in the MD main stretching is preferably (Tg+20)° C. or higher and (Tc+20)° C. or lower, and more preferably (Tg+25)° C. or higher and (Tc+10)° C. or lower. If the stretching temperature is lower than (Tg+20)° C., the stretching stress may become high and the film may be prone to breakage during TD stretching, whereas if the temperature exceeds (Tc+20)° C., thickness unevenness may become large.

[0069] The second stage of MD main stretching is preferably a heated roll stretching method. It is preferable to use a ceramic roll with a surface roughness Ra of 0.2 μm or less as the heated roll. Using a roll with an Ra of more than 0.2 μm may result in the film sliding on the roll during stretching, which is undesirable as it may scratch the film surface. Furthermore, the stretching start point on the roll may become non-uniform in the width direction or may fluctuate, resulting in thickness variations. In the second stage of MD main stretching, regardless of the width-direction thickness profile of the film after the first stage of MD main stretching, the film is preferably stretched in a linear, tightly contacted state in the width direction on the roll, resulting in uniform heated stretching in the width direction. Here, Ra refers to the centerline average roughness, which is the average height of irregularities (unit: μm), and is a value specified in JIS B 0601.

[0070] In the stretching process, it is preferable to include a relaxation step in the MD direction (hereinafter also referred to as MD relaxation) between the MD stretching step and the subsequent TD stretching step. The lower limit of the MD relaxation rate is preferably 1%, more preferably 3%, and particularly preferably 5%. If it is 1% or more, the amorphous components in the film are relaxed, which can reduce the stretching stress in the subsequent TD stretching step, thereby preventing the film from becoming too oriented, thereby suppressing springback and curling after molding. The upper limit of the MD relaxation rate is preferably 10%, more preferably 8%, and particularly preferably 6%. If it is 10% or less, wrinkles due to shrinkage can be suppressed, improving the quality of the film and suppressing a decrease in mechanical strength due to orientation relaxation. The MD relaxation method is not particularly limited, but an example is a method in which a film is heated with a hot air heater and then relaxed using the speed difference between rolls.

[0071] The lower limit of the TD stretching temperature is preferably 90°C, more preferably 100°C, and particularly preferably 110°C. If the temperature is 90°C or higher, the stretching stress can be reduced, thereby suppressing springback and curling after molding. The upper limit of the TD stretching temperature is preferably 140°C, more preferably 130°C, and particularly preferably 120°C. If the TD stretching temperature exceeds 140°C, not only will film formability decrease, but the orientation of the obtained film in the TD direction will be weak, which may result in a decrease in formability.

[0072] The lower limit of the stretching ratio in the TD direction is preferably 2.5 times, more preferably 3.0 times, and particularly preferably 3.5 times. When it is 2.5 times or more, not only is the mechanical strength and thickness unevenness of the film improved, but also formability is improved. The upper limit of the stretching ratio in the TD direction is preferably 5.0 times, more preferably 4.5 times, and particularly preferably 4.0 times. By setting it to 5.0 times or less, an increase in orientation in the TD direction can be suppressed, and the occurrence of springback and curling after molding can be suppressed.

[0073] As for the TD stretching pattern, in addition to the commonly used linear stretching pattern in which the stretch ratio increases linearly, multistage stretching can be preferably used. Multistage stretching involves performing two or more stretching steps in comparison with the usual one-stage stretching, i.e., linear stretching pattern, as shown in an example in Figure 1, and can reduce the stretching stress applied during TD stretching. As a result, even with the same stretch ratio, excessively high orientation in the TD can be prevented, and springback and curling after forming can be suppressed.

[0074] The multistage stretching in the TD direction is preferably two to five stage stretching. Multistage stretching allows the stretching stress to be changed by changing the temperature of each stretching step, which is preferable because it allows the stretching stress during TD stretching to be reduced. Two or more stage stretching can reduce the stretching stress, preventing excessively high TD orientation even at the same stretch ratio, thereby suppressing springback and curling after forming. Five or fewer stage stretching can prevent the equipment from becoming too large. In multistage stretching, a temperature pattern is preferably used in which the temperature is lowered from the first stage to the final stage, with a temperature difference of 2°C or more between each stage. Furthermore, when multistage stretching is performed, a constant length zone can be appropriately provided after each stretching stage. By providing a constant length zone after each stretching stage, the internal stress generated during stretching can be alleviated in the constant length zone, thereby further reducing the stretching stress when the next stretching is performed.This prevents the TD orientation from becoming too high even with the same stretching ratio, and suppresses springback and curling after molding.

[0075] In the heat setting step, the lower limit of the heat setting temperature is preferably 170°C, more preferably 180°C, and particularly preferably 190°C. If the temperature is 170°C or higher, the heat shrinkage rate can be reduced. The upper limit of the heat setting temperature is preferably 230°C, more preferably 220°C, and particularly preferably 210°C. If the temperature is 230°C or lower, the decrease in mechanical strength due to the brittleness of the biaxially oriented polyamide film can be suppressed.

[0076] In the heat-relaxing step, the lower limit of the relaxation rate in the TD direction is preferably 0.5%, more preferably 1.0%, and particularly preferably 2.0%. If it is 0.5% or more, the thermal shrinkage rate in the TD direction can be kept low. The upper limit of the relaxation rate in the TD direction is preferably 10%, more preferably 8%, and particularly preferably 6%. If it is 10% or less, the occurrence of slack and the like can be prevented, and flatness can be improved.

[0077] To further improve adhesion and wettability, biaxially oriented polyamide films can be subjected to corona treatment, coating treatment, flame treatment, etc. These treatments can be carried out during the manufacturing process of the biaxially oriented polyamide film. Alternatively, the film can be treated by unwinding it from a mill roll or a slit roll.

[0078] [Configuration and Properties of Intermediate Layer] The lower limit of the thickness of the intermediate layer of the present invention is preferably 5 μm, more preferably 10 μm. By making it 5 μm or more, good mechanical properties and moldability can be obtained. The upper limit of the thickness of the intermediate layer is preferably 100 μm, more preferably 70 μm, and particularly preferably 40 μm.

[0079] The lower limit of the puncture strength of the intermediate layer of the present invention is preferably 0.5 N / μm, and more preferably 0.6 N / μm. When the puncture strength is 0.5 N / μm or more, good formability can be obtained. The upper limit of the puncture strength of the intermediate layer is not particularly limited, but is preferably 1.0 N / μm or less. When it exceeds 1.0 N / μm, the formability improvement effect may become saturated. Here, the puncture strength (unit: N / μm) in the present invention refers to the strength (unit: N) when a needle with a tip radius of 0.5 mm penetrates a film at a puncture speed of 50 mm / min, and the strength (unit: N) when the needle penetrates the film is divided by the thickness of the film (unit: μm).

[0080] The lower limit of the heat shrinkage rate in the MD and TD of the biaxially oriented polyamide film of the present invention is preferably 0.5%, more preferably 0.8%, and particularly preferably 1.0%. The upper limit of the heat shrinkage rate in the MD and TD is preferably 3.0%, more preferably 2.5%, and particularly preferably 2.0%. By keeping the heat shrinkage rate at 3.0% or less, dimensional changes when heated in the secondary processing step can be suppressed, and the occurrence of wrinkles can be reduced.

[0081] In a tensile stress relaxation test at 25°C, the intermediate layer of the present invention preferably has a stress decay rate, as shown by the following formula (1), of 12% or more, and more preferably 14% or more, in both the MD and TD directions: Stress decay rate after 2-second hold (%) = 100 × (σ0 - σ1) / σ0 Formula (1) Here, σ0 represents the tensile stress value of the film immediately after applying a tensile force to the film at a pulling rate of 200 mm / min to apply the 50% tensile strain, and σ1 represents the tensile stress value when the 50% tensile strain is held for 2 seconds.

[0082] The biaxially oriented polyamide film of the present invention preferably satisfies the following formulas (2) and (3), where Y(MD) is the stress at 30% elongation in the MD direction of the film (F30 value) and Y(TD) is the stress at 30% elongation in the TD direction of the film at 25°C: Formula (2) 100 MPa≦Y(MD)≦150 MPa Formula (3) 110 MPa≦Y(TD)≦200 MPa

[0083] By setting the Y(MD) value to 100 MPa or more, excellent formability can be obtained. On the other hand, by setting the Y(MD) value to 150 MPa or less, the stress of the film after molding can be prevented from becoming too large, and springback and warpage resistance after molding can be reduced, resulting in good formability. Similarly, by setting the Y(TD) value to 110 MPa or more, excellent formability can be obtained. By setting the Y(TD) value to 200 MPa or less, the stress of the film after molding can be prevented from becoming too large, and springback and warpage resistance after molding can be reduced, resulting in good formability.

[0084] The biaxially oriented polyamide film of the present invention preferably satisfies the following formulas (4) and (5), where X(MD) is the stress at 3% elongation in the MD direction of the film (F3 value), X(TD) is the stress at 3% elongation in the TD direction of the film at 25°C (F3 value), Z(MD) is the value of Y(MD) / X(MD), and Z(TD) is the value of Y(TD) / X(TD): Formula (4) 1.4≦Z(MD)≦2.2 Formula (5) 2.5≦Z(TD)≦3.5

[0085] By setting the Z (MD) value to 1.4 or more, excellent formability can be obtained. On the other hand, by setting the Z (MD) value to 2.2 or less, the stress of the film after molding can be prevented from becoming too large, and springback and warpage resistance after molding can be reduced, resulting in good formability. Similarly, by setting the Z (TD) value to 12.5 or more, excellent formability can be obtained. By setting the Z (TD) value to 3.5 or less, the stress of the film after molding can be prevented from becoming too large, and springback and warpage resistance after molding can be reduced, resulting in good formability.

[0086] [Metal Foil] Various metal foils such as aluminum and stainless steel can be used as the metal foil, with aluminum foil being preferred in terms of moisture resistance, processability such as ductility, and cost. A general soft aluminum foil can be used as the aluminum foil. Among these, iron-containing aluminum foil is preferred in terms of pinhole resistance and excellent ductility during molding. The iron content in the iron-containing aluminum foil (100% by mass) is preferably 0.1 to 9.0% by mass, more preferably 0.5 to 2.0% by mass. When the iron content is equal to or greater than the lower limit, pinhole resistance and ductility are excellent. When the iron content is 9.0% by mass or less, flexibility is excellent. The thickness of the metal foil is preferably 9 to 200 μm, more preferably 15 to 100 μm, in terms of barrier properties, pinhole resistance, and processability.

[0087] [Sealant Layer] The sealant layer may be a resin film made of a polyolefin resin or an acid-modified polyolefin resin obtained by graft-modifying a polyolefin resin with an acid such as maleic anhydride. Examples of the polyolefin resin include low-density, medium-density, and high-density polyethylene; ethylene-α-olefin copolymer; homo-, block-, or random polypropylene; and propylene-α-olefin copolymer. These polyolefin resins may be used alone or in combination of two or more.

[0088] The sealant layer may be a single-layer film or a multilayer film, and may be selected depending on the required function. For example, to provide moisture resistance, a multilayer film containing a resin such as an ethylene-cyclic olefin copolymer or polymethylpentene may be used. The sealant layer may also contain various additives such as a flame retardant, a slip agent, an antiblocking agent, an antioxidant, a light stabilizer, and a tackifier. The thickness of the sealant layer is preferably 10 to 100 μm, and more preferably 20 to 60 μm.

[0089] [Laminate] The laminate of the present invention preferably comprises a substrate layer, an intermediate layer, a metal foil, and a sealant layer laminated in this order. The laminate may also be configured by providing an adhesive layer, a printed layer, or the like between the substrate layer and the intermediate layer, between the intermediate layer and the metal foil, and / or between the metal foil and the sealant layer.

[0090] The laminate of the present invention is suitable for use in cold forming applications. The present invention also provides a battery packaging material using the laminate. In particular, the present invention provides a battery packaging material for laminated lithium-ion batteries. In another aspect, the present invention provides a pharmaceutical packaging material.

[0091] The films and laminates were evaluated by the following measurement methods. Unless otherwise specified, measurements were carried out in a measurement room at 23° C. and a relative humidity of 65%.

[0092] [Film Thickness] Measured using a dial gauge in accordance with JIS K7130-1999 Method A.

[0093] [Thickness Unevenness] A sample of 800 mm in the TD direction and 40 mm in the longitudinal direction was taken from the film roll, and the thickness in the width direction was continuously measured at 5 m / s using a film tester continuous thickness measuring device (manufactured by Fujiwork Co., Ltd.). The maximum thickness during measurement was defined as Tmax, the minimum thickness as Tmin, and the average thickness as Tave, and the thickness unevenness in the TD direction of the film was calculated using the following formula (6): Thickness Unevenness = {(Tmax - Tmin) / Tave} x 100 (%).

[0094] [Haze] According to a method in accordance with JIS-K-7105, a sample was measured at three different locations using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., model NDH2000), and the average value was taken as the haze (unit: [%]).

[0095] [Heat shrinkage] The heat shrinkage of biaxially oriented polyester films was measured using a dimensional change test method in accordance with JIS-C-2318, except that the test temperature was 150°C and the heating time was 15 minutes. Samples were cut out from the MD and TD directions, respectively, and measurements were taken. The heat shrinkage of biaxially oriented polyamide films was measured using a dimensional change test method in accordance with JIS-C-2318, except that the test temperature was 160°C and the heating time was 10 minutes. Samples were cut out from the MD and TD directions, respectively, and measurements were taken.

[0096] [Puncture Strength] Measurements were made in accordance with "2. Test Methods for Strength, etc." in "Specifications and Criteria for Foods, Food Additives, etc., Part 3: Apparatus and Containers / Packaging" (Ministry of Health and Welfare Notification No. 20, 1982) under the Food Sanitation Act. A needle with a tip radius of 0.5 mm was pierced into the film at a puncture speed of 50 mm / min, and the strength (N) at which the needle penetrated the film was divided by the film thickness (μm) to determine the puncture strength. Measurements were made at room temperature (23°C) and the unit was [N / μm].

[0097] [Strength and Elongation of Biaxially Oriented Film] Test samples measuring 15 mm wide and 100 mm long were cut out in the machine direction of the film in accordance with JIS K 7127. The test samples were subjected to a tensile test using a tensile tester (Shimadzu Corporation, Autograph AG-I) with a gauge length of 50 mm and a tensile speed of 200 mm / min. The stress value (F3) at 3% deformation and the stress value (F30 value) at 30% deformation of the test sample were calculated from the obtained stress-strain curve.

[0098] [Stress decay rate of biaxially oriented film] A test sample 15 mm wide and 100 mm long was cut out from the film in the MD direction. A 50% tensile strain was applied using a tensile tester (Shimadzu Corporation, Autograph AG-I) under conditions of a gauge length of 50 mm and a tensile speed of 200 mm / min. The tensile strain was maintained for 100 seconds from the time the 50% tensile strain was applied, and the change in stress during this period was recorded. From the obtained graph of holding time vs. stress, the stress value immediately after the 50% strain application and after 2 seconds of holding was read, and the stress decay rate after 2 seconds of holding was calculated using the following formula (1):

[0099] Formula (1) Stress decay rate after 2 seconds (%) = 100 × (σ0 - σ1) / σ0

[0100] Here, σ0 represents the tensile stress of the film immediately after a tensile force is applied to the film at a pulling rate of 200 mm / min to apply the 50% tensile strain, and σ1 represents the stress value when a tensile strain of σ0 to 50% is maintained for 2 seconds.

[0101] [Cold formability] The laminate was placed in a die set mold (convex shape 90 mm x 50 mm) and pressed at 23°C using a press to perform drawing. The drawing depth during forming was increased in 0.2 mm increments, and the maximum depth at which the laminate was not damaged was taken as the drawing depth and evaluated as follows: A: Drawing depth is 8 mm or more B: Drawing depth is 6 mm to less than 8 mm C: Drawing depth is 4 mm to less than 6 mm D: Drawing depth is less than 4 mm

[0102] [Springback after molding] The laminate was placed in a die set mold (convex shape 90 mm x 50 mm) and pressed at 23°C using a press to perform drawing. The mold pressing speed during drawing was 200 mm / min, and the holding time after pressing was 2 seconds. The container depth after removing the mold was measured, and the retention rate (ratio of container depth to molded depth) was calculated and evaluated as follows: A: Retention rate is 90% or more B: Retention rate is 80% or more but less than 90% C: Retention rate is 70% or more but less than 80% D: Retention rate is less than 70%

[0103] [Curling after molding] Samples that could be molded without breakage in the cold formability evaluation were placed on a horizontal table with the convex part facing up. The average height at which the four corners of the test piece rose from the table after molding was taken as the average warpage height, and evaluation was performed according to the following criteria. A: The average warpage height was less than 3 mm. B: The average warpage height was 3 mm or more and less than 5 mm. C: The average warpage height was 5 mm or more and less than 10 mm. D: The average warpage height was 10 mm or more.

[0104] [Preparation of biaxially oriented polyester films] (Polyester resin A) A fossil fuel-derived PET resin with terephthalic acid / ethylene glycol = 100 / / 100 (mol%) (intrinsic viscosity 0.62 dL / g) was used. (Polyester resin B) A fossil fuel-derived PET resin with terephthalic acid / ethylene glycol = 100 / / 100 (mol%) and a porous silica particle content of 0.72 mass% (intrinsic viscosity 0.62 dL / g) was used.

[0105] [PET-1] An extruder was charged with 87 parts by weight of polyester resin A and 13 parts by weight of polyester resin B. The resins were melted at 280°C in the extruder, then cast from a T-die and adhered to a 10°C cooling roll by electrostatic adhesion to obtain an unstretched sheet. The resulting unstretched film was then preheated with a roll heated to 80°C, heated to 120°C with an infrared heater, and stretched in the MD direction at a stretch ratio of 3.7x in one stage. Subsequently, the film was stretched in the TD direction at a preheating temperature of 120°C, a stretching temperature of 140°C, and a stretch ratio of 4.6x in a tenter-type transverse stretching machine. The film was then heat-set at 210°C, subjected to a 5% relaxation treatment in the TD direction, and corona-treated on one side, resulting in a 12 μm-thick biaxially oriented polyester film. The evaluation results are shown in Table 1.

[0106] [PET-2, PET-3] Biaxially oriented polyester films with a thickness of 12 μm were produced in the same manner as for PET-1, except that the stretching ratio in the MD direction was changed to the ratio shown in Table 1. The evaluation results are shown in Table 1.

[0107] [PET-4] A 3-stage roll stretching process was used in the MD stretching process. The rolls were heated to a heating temperature of 115°C, and the film was stretched in the MD direction at a total stretch ratio of 4.5 times, with the first stage being 1.24 times, the second stage being 1.4 times, and the third stage being 2.6 times. A 12 μm-thick biaxially oriented polyester film was produced in the same manner as in PET-1. The evaluation results are shown in Table 1.

[0108] [PET-5] Polyester resin A and polyester resin B were charged into an extruder in the ratios shown in Table 1. The resins were melted at 280°C in the extruder, then cast from a T-die and adhered to a 10°C cooling roll by electrostatic adhesion to obtain an unstretched sheet. The resulting unstretched film was then preheated with a roll heated to 80°C, heated to 120°C with an infrared heater, and stretched in one stage in the MD direction at a stretch ratio of 5.0. Immediately after MD stretching, the film was passed through a heating furnace set at 95°C with a hot air heater, and subjected to a 3% relaxation treatment in the MD direction using the speed difference between the rolls at the entrance and exit of the heating furnace. Next, the stretching method in the tenter-type transverse stretching machine was changed to three-stage stretching, and 1-m constant-length regions were provided between the first and second stages and between the second and third stages. The stretching temperature and stretch ratio at each stage are shown in Table 1. The film was then heat-set at 210°C, subjected to a 5% thermal relaxation treatment in the width direction, and one side of the film was subjected to a corona treatment to prepare a biaxially oriented polyester film having a thickness of 12 µm. The evaluation results are shown in Table 1.

[0109] [PET-6 to PET-9] Biaxially oriented polyester films with a thickness of 12 μm were produced in the same manner as for PET-1, except that the stretching conditions in the MD direction and the TD direction were changed to those shown in Table 1. The evaluation results are shown in Table 1.

[0110]

[0111]

[0112] [Preparation of biaxially oriented polyamide film] (Polyamide 6) A polyamide 6 resin with a relative viscosity of 2.9 and a melting point (Tm) of 220°C was used. (Polyamide MXD6) A polyamide MDX6 resin with a relative viscosity of 2.2 and a melting point (Tm) of 238°C was used. [Masterbatch containing silica fine particles and organic lubricant] 93.5% by mass of the above polyamide 6, 5% by mass of porous silica fine particles (weight average particle diameter = 3.0 μm, pore volume = 1.8 ml / g), and 1.5% by mass of ethylene bisstearylamide (Lightamide WE-183, manufactured by Kyoeisha Chemical Co., Ltd.) were blended, melt-kneaded and extruded using a twin-screw extruder, and cut into pellets to obtain a masterbatch.

[0113] [ONY-1] The raw materials were blended in a ratio of 85 parts by weight of polyamide 6, 3 parts by weight of polyamide MXD6, and 12 parts by weight of a masterbatch of silica fine particles and ethylene bisamide. The blended raw materials were adjusted to a moisture content of 0.1% by weight, and then extruded as a molten film from a T-die at 260 ° C. using an extruder. The film was then adhered to a cooling roll at 30 ° C. by electrostatic adhesion and cooled to solidify, yielding an unstretched film with a thickness of 200 μm. The Tg of this unstretched film was 41 ° C. and the Tc was 69 ° C.

[0114] This unstretched film was stretched 1.03 times at a stretching temperature of 80°C in the first stage of MD pre-stretching, followed by 1.03 times at a stretching temperature of 80°C in the second stage of MD pre-stretching. It was then stretched 2.1 times at 85°C in the first stage of MD main stretching, and further stretched 1.53 times at a stretching temperature of 70°C in the second stage of MD main stretching. This MD-stretched film was continuously introduced into a tenter and stretched 4.0 times in the TD direction at 130°C, heat-set at 210°C, and further relaxed 5.0% in the TD direction at 210°C. It was then cooled to 100°C, and one side of the film was corona-treated, resulting in a 15 μm-thick biaxially oriented polyamide film. The evaluation results are shown in Table 2.

[0115] [ONY2, ONY-3] Biaxially oriented polyamide films were obtained in the same manner as in Examples, except that the temperature and magnification of the MD pre-stretching and the magnification of the MD main stretching were changed as shown in Table 2. The evaluation results are shown in Table 2.

[0116] [ONY-4] The raw materials were blended in a ratio of 85 parts by weight of polyamide 6, 3 parts by weight of polyamide MXD6, and 12 parts by weight of a masterbatch of silica fine particles and ethylene bisamide. The blended raw materials were adjusted to a moisture content of 0.1% by weight, and then extruded as a molten film from a T-die at a temperature of 260 ° C. using an extruder. The film was then adhered to a cooling roll at 30 ° C. by electrostatic adhesion and cooled to solidify, resulting in an unstretched film with a thickness of 200 μm. The Tg of this unstretched film was 41 ° C. and the Tc was 69 ° C.

[0117] This unstretched film was subjected to MD pre-stretching at a stretching temperature of 85°C and a stretching ratio of 1.07 times using a roll stretching machine. Subsequently, as the first-stage MD main stretching, it was stretched to 2.0 times at 85°C, and as the second-stage MD main stretching, it was further stretched to 2.0 times at a stretching temperature of 70°C. Immediately after MD stretching, the film was passed through a heating oven set at 85°C using a hot air heater, and subjected to a 5% relaxation treatment in the MD direction using the speed difference between the rolls at the entrance and exit of the heating oven. This MD-stretched film was continuously introduced into a tenter and stretched to 4.0 times in the TD direction at 130°C. It was heat-set at 210°C and further relaxed 5.0% in the TD direction at 210°C. Subsequently, it was cooled to 100°C, and one side of the film was corona-treated, resulting in a 15 μm-thick biaxially oriented polyamide film. The evaluation results are shown in Table 2.

[0118] [ONY-5] The raw materials were blended to contain 85% by mass of polyamide 6, 3% by mass of polyamide MXD6, and 12% by mass of a masterbatch of silica fine particles and ethylene bisamide. The blended raw materials were adjusted to a moisture content of 0.1% by mass, and then extruded as a molten film at a temperature of 260 ° C. from a T-die using an extruder. The film was then adhered to a cooling roll at 30 ° C. by electrostatic adhesion and cooled to solidify, resulting in an unstretched film with a thickness of 200 μm. The Tg of this unstretched film was 41 ° C. and the Tc was 69 ° C.

[0119] This unstretched film was subjected to a first-stage MD pre-stretching at a stretching temperature of 80°C, stretching by 1.03 times, followed by a second-stage MD pre-stretching at a stretching temperature of 80°C, stretching by 1.03 times. The first-stage MD main stretching was then performed at 85°C, stretching by 2.1 times, and the second-stage MD main stretching was performed at a temperature of 70°C, stretching by 1.53 times. This MD-stretched film was continuously introduced into a tenter, and the tenter stretching method was a three-stage stretching method, with 1 m constant length regions between the first and second stages and between the second and third stages, and stretching in the TD direction. The film was heat-set at 210°C, further relaxed 5.0% in the TD direction at 210°C, and then cooled to 100°C. One side of the film was corona-treated, and a 15 μm-thick biaxially oriented polyamide film was produced. The evaluation results are shown in Table 2.

[0120] [ONY-6, ONY-7, ONY-8] Biaxially oriented polyamide films were produced in the same manner as ONY-1, except that MD pre-stretching was not performed and MD main stretching was performed at the temperature and magnification shown in Table 2. The evaluation results are shown in Table 2.

[0121] [ONY-9] A biaxially oriented polyamide film was produced in the same manner as ONY-1, except that MD pre-stretching was not performed and MD main stretching was performed in only one stage at the temperature and magnification shown in Table 2. The evaluation results are shown in Table 2.

[0122]

[0123]

[0124] [Examples 1 to 5, Comparative Examples 1 to 9] Dry lamination was performed using the biaxially oriented polyester films PET-1 to PET-9 and biaxially oriented polyamide films ONY-1 to ONY-9 described above in the combinations shown in Table 3. The adhesive used was an ester-based adhesive obtained by mixing 33.6 parts by weight of base agent (TM569, manufactured by Toyo-Morton Co., Ltd.), 4.0 parts by weight of curing agent (CAT10L, manufactured by Toyo-Morton Co., Ltd.), and 62.4 parts by weight of ethyl acetate, and the adhesive was applied in an amount of 3.0 g / m2. Next, the same ester-based adhesive as above was applied to the surface of the biaxially oriented polyamide film side of the laminate obtained above in an amount of 3.0 g / m2, and aluminum foil (8079 material, thickness 40 μm) was placed on top of it, followed by dry lamination. Next, the aluminum foil of the biaxially oriented polyester film / biaxially oriented polyamide film / aluminum foil laminate obtained above was dry-laminated to a 70 μm thick sealant film of unstretched polypropylene (Toyobo Co., Ltd., unstretched polypropylene film P1146) using the same ester-based adhesive as above. The resulting film was wound up and kept at 40° C. for 3 days, after which the laminate was evaluated. The evaluation results are shown in Table 3.

[0125]

[0126] As shown in Table 3, the laminates of the Examples had excellent formability and resistance to deterioration of dimensional accuracy after forming due to springback and warpage, and therefore had excellent dimensional accuracy in forming. On the other hand, the laminates of the Comparative Examples had insufficient cold formability and suppression of springback and curl after forming.

Claims

DEPCT681. A stacked object consisting of a base layer, an intermediate layer, a metal foil, and a sealant layer, in which the base layer is a bidirectional polyester film conforming to (a) to (c) below, and the intermediate layer is a bidirectional polyamide film conforming to (d) to (f) below. (a) Penetration strength is 0.45 N / µm or greater and not exceeding 0.80 N / µm. (b) Thermal shrinkage at 150 °C is not exceeding 2.5% in both MD and TD directions. (c) In the relaxation test, At 25°C, the stress reduction rate, as shown by Equation(1), is 15.0% or more in both the MD and TD directions. Equation(1) Stress reduction rate (%) = 100 x (Sigma 0 - Sigma 1) / Sigma 0, where Sigma 0 represents the tensile stress immediately after the 50% tensile strain has been applied by tensile force to the film at a tensile velocity of 200 mm / min, and Sigma 1 represents the tensile stress at the time the 50% tensile strain is maintained for 2 seconds. (d) The penetration strength, as measured according to JISZ7102, is 0.5 N / µm or more and not exceeding 1.0 N / µm(e)The thermal shrinkage rate at 160 °C is not more than 3.0% in both MD and TD directions.(f)In the tensile stress relaxation test at 25 °C, the stress reduction rate shown by Equation (1) is 12.0% or more in both MD and TD directions.2 The stacked material specified in claim 1 on the base material layer is as follows (g) (g) at 25 °C at the given time, the elongation stress of 3% in both MD and TD directions of the film is X(MD) and The stresses X(TD) and 30% elongation in the MD and TD directions are both Y(MD) and Y(TD), and the values ​​of Y(MD) / X(MD) and Y(TD) / X(TD) are both Z(MD) and Z(TD), which all satisfy the following equations (2) through (5): Equation (2) 125 MPa is less than or equal to Y(MD) less than or equal to 155 MPa; Equation (3) 140 MPa is less than or equal to Y(TD) less than or equal to 190 MPa; Equation (4) 1.3 is less than or equal to Z(MD) less than or equal to 1.6; Equation (5) 1.7 is less than or equal to Z(TD) less than or equal to 2.

23. The stacked material specified in claim 1 or 2 that satisfies (h) the following (h) in the intermediate layer satisfies equations (6) to (9) at 25 degrees Celsius at a given time, the elongation stress of 3% in the MD and TD directions of the film is both X(MD) and X(TD), and the elongation stress of 30% in the MD and TD directions is both Y(MD) and Y(TD), and the values ​​of Y(MD) / X(MD) and Y(TD) / X(TD) are both Z(MD) and Z(TD), all satisfies equations (6) to (9) below. Equation (6) 100 MPa less than 1.5 or equal to Y(MD) less than or equal to 150 megapascals Equation (7) 110 megapascals less than or equal to Y(TD) less than or equal to 200 megapascals Equation (8) 1.4 less than or equal to Z(MD) less than or equal to 2.2 Equation (9) 2.5 less than or equal to Z(TD) less than or equal to 3.

54. Any stacked object specified in any of Claims 1 to 3, which is further incorporated with a printed layer 5. Exterior finishing material of a battery that is incorporated with any stacked object specified in any of Claims 1 to 4;

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