Cell pouch film and method for manufacturing the same

Abstract

The present invention provides a cell pouch film and a method for manufacturing the same, which exhibits excellent mechanical strength, low stress applied to the film resulting in low deviation in mechanical strength, and excellent moldability. [Solution] A cell pouch film is provided, comprising: a barrier layer made of metal and surface-treated on both sides; an adhesive layer formed on both sides of the barrier layer; and a functional raw material layer formed on both sides of the adhesive layer, wherein the difference between the breaking strength in the longitudinal direction (MD) and the breaking strength in the width direction (TD) is 40 N / 15 mm or less, and the difference between the elongation rate in the longitudinal direction (MD) and the elongation rate in the width direction (TD) of the film is 6% or less.

Description

Technical Field

[0001] This specification discloses a film for a cell pouch and a method for manufacturing the same. [National Research and Development Project Supported by the Invention] [Problem Specific Number] 1415185612 [Problem Number] 20022450 [Department Name] Ministry of Industry, Trade and Resources [Problem Management (Specialty) Agency Name] Korea Institute of Industrial Technology Evaluation and Management [Research Project Name] Material Parts Package Type (Top Company) [Research Problem Name] Development of Next-generation Secondary Battery Pouch with High Adhesive Strength (60°C) Twice or More [Contribution Rate] 1 / 1 [Problem Execution Agency Name] Kurimura Chemical Co., Ltd. [Research Period] January 1, 2023 ~ December 31, 2023

Background Art

[0002] Generally, a pouch-type battery used in electric vehicles, etc. has the advantages of being easier to deform in form and having a higher energy density compared to cylindrical and square batteries. Such a cell pouch is generally manufactured by performing, in this order, a first step of surface-treating one side of a metal layer, a second step of surface-treating the other side of the metal layer, a third step of laminating an outer layer on one side, and a fourth step of laminating a sealant layer on the other side.

[0003] Korean Published Patent Publication No. 10-2016-0070468 discloses such a process. However, in such conventional processes, coating, drying, and winding are repeated sequentially in each step, which increases the likelihood of running losses and process defects occurring during the feeding of the raw material. Furthermore, conventional processes have the problem of increased stress on the film due to their slow speed and repeated winding. Moreover, the high tension of the drive rolls that feed the film causes changes in the tensile curve of the film, resulting in problems such as changes in the mechanical strength of the film in the longitudinal (MD) and widthwise (TD) directions. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Korean Published Patent Gazette No. 10-2016-0070468 [Patent Document 2] Korean Published Patent Gazette No. 10-2022-0031820 [Overview of the project] [Problems that the invention aims to solve]

[0005] One aspect of the present invention is to provide a cell pouch film and a method for manufacturing the same that have excellent mechanical strength, low stress applied to the film resulting in low deviation in mechanical strength, and excellent moldability. [Means for solving the problem]

[0006] In one aspect of the present invention, the present invention provides a cell pouch film comprising: a barrier layer made of metal and surface-treated on both sides; an adhesive layer formed on both sides of the barrier layer; and a functional raw material layer formed on both sides of the adhesive layer, wherein the difference between the breaking strength in the longitudinal direction (MD) and the breaking strength in the width direction (TD) is 40 N / 15 mm or less.

[0007] In another aspect, the present invention provides a cell pouch comprising the cell pouch film.

[0008] In another aspect, the present invention provides a method for manufacturing a cell pouch film, comprising: a double-sided surface treatment step of applying a surface treatment to both sides of a metal base material that forms a barrier layer; a single-sided surface coating step of applying an adhesive to one side of the surface-treated metal base material to form an adhesive layer; and a lamination step of laminating a functional base material to one side of the adhesive layer to form a functional base material layer. [Effects of the Invention]

[0009] A cell pouch film and a method for manufacturing the same according to one embodiment of the present invention have the effects of excellent mechanical strength, low stress applied to the film, low deviation in mechanical strength, and excellent moldability. [Brief explanation of the drawing]

[0010] [Figure 1] This figure schematically shows a cross-section of a film according to one embodiment of the present disclosure. [Figure 2] This is a schematic diagram of a manufacturing apparatus for cell pouch film according to one embodiment of the present invention. [Figure 3] This is a stress-strain curve of a cell pouch film according to one embodiment of the present invention. [Modes for carrying out the invention]

[0011] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings.

[0012] The embodiments of the present invention disclosed herein are merely exemplified for the purpose of explanation, and the embodiments of the present invention can be implemented in various forms and should not be construed as being limited to the embodiments described in the text. The present invention can be subjected to various modifications and can have various forms. The embodiments are not intended to limit the present invention to a specific disclosed form, and should be understood to include all modifications, equivalents, and alternatives included in the spirit and technical scope of the present invention.

[0013] In this specification, when a certain part "includes" a certain component, this means that, unless otherwise specified, it may further include other components rather than excluding other components.

[0014] Throughout the specification, the same reference numerals are assigned to similar parts. Throughout the specification, when a part such as a film, region, plate, etc. is "above" or "on" another part, this includes not only the case where it is directly above the other part but also the case where other parts are interposed therebetween. Throughout the specification, terms such as first, second, etc. are only used to describe various components, and the components should not be limited by such terms. The terms are used only for the purpose of distinguishing one component from another.

[0015] In this specification, "cell" means a battery, and has the broadest meaning including all kinds of batteries such as secondary batteries like lithium-ion batteries and lithium polymer batteries, and portable rechargeable batteries.

[0016] In this specification, "cell pouch" means a structure in which cell components such as a positive electrode, a negative electrode, and a separator are impregnated with an electrolyte solution and stored, and in the broadest sense includes all those in which a film having a laminated structure considering gas barrier properties, flexibility, electrolyte resistance, and thermal adhesiveness, etc. for storing the cell components is processed into a bag shape, a box shape, etc.

[0017] In this specification, "barrier property" means the performance of blocking water vapor from the outside of the battery.

[0018] In this specification, "flexibility" means the degree of bending of the cell and / or the cell pouch, and the better the flexibility, the easier the cell and / or the flexible cell pouch can be bent.

[0019] Cell pouch film FIG. 1 is a diagram schematically showing a cross-section of a film according to an embodiment of the present disclosure.

[0020] In an exemplary embodiment of the present invention, it includes a barrier layer 300 made of metal and having surface treatment on both sides; adhesive layers 200 and 400 formed on both sides of the barrier layer; and functional base film layers 100 and 500 formed on both sides of the adhesive layers 2, and provides a film for a cell pouch in which the difference between the breaking strength in the longitudinal direction (Machine direction, MD) and the breaking strength in the width direction (Machine direction, TD) is 40 N / 15 mm or less.

[0021] An embodiment of the present disclosure can provide a film for a cell pouch including a sealant layer 500; an inner surface adhesive layer 400 laminated on the sealant layer 500; a barrier layer 300 laminated on the inner surface adhesive layer 400; an outer surface adhesive layer 200 laminated on the barrier layer 300; and an outer layer 100 formed on the outer surface adhesive layer 200, wherein the barrier layer 300 includes a metal layer 320 and surface treatment layers 310 and 330 uniformly coated on both sides of the metal layer 320, respectively.

[0022] In one embodiment, an extruded resin layer may be further formed between the adhesive layer and the functional raw material layer. The extruded resin layer can improve the flexibility, adhesion, and insulation properties of the pouch. The extruded resin layer contains an olefin resin such as a polypropylene resin. The extruded resin layer may have a thickness of about 5 to 80 μm. Alternatively, the internal layer of the cell pouch film may be composed of the extruded resin layer and the sealant layer without the internal adhesive layer. If there is no internal adhesive layer as described above, the extruded resin layer may also serve the role of the internal adhesive layer.

[0023] In one embodiment, the barrier layer can block the entry and exit of external moisture and air, as well as gases generated internally. The barrier layer is not particularly limited as long as it is made of a metal with gas barrier properties. The barrier layer may include one or more selected from a metal thin film and a metal vapor-deposited layer. In this case, the metal thin film may be made of metal foil, and the metal vapor-deposited layer may be formed by vacuum deposition onto a separate plastic film, such as polyethylene terephthalate (PET), polyethylene (PE), or polypropylene (PP).

[0024] In one embodiment, the difference between the breaking strength in the longitudinal direction (Machine direction, MD) and the breaking strength in the width direction (Machine direction, TD) of the film is 40 N / 15 mm or less. More specifically, the difference between the breaking strength in the longitudinal direction (MD) and the breaking strength in the width direction (TD) of the film may be 5 N / 15 mm or more, 10 N / 15 mm or more, 15 N / 15 mm or more, 20 N / 15 mm or more, 23 N / 15 mm or more; 40 N / 15 mm or less, 35 N / 15 mm or less, 30 N / 15 mm or less, 25 N / 15 mm or less, or 23 N / 15 mm or less, but is not limited to these.

[0025] This invention employs an in-line 1-pass 3-coating (1P3C) system, which allows for three or more coating processes to be performed in a single piece of equipment, unlike conventional methods that repeatedly perform coating, drying, and winding processes at each stage. This reduces the probability of running losses and process defects that occur during the feeding of the raw material. Furthermore, the method of this invention results in a higher process speed and fewer winding cycles, reducing the stress applied to the film. The low tension of the drive rolls that feed the film prevents changes in the film's tensile curve, and thus the mechanical strength of the film in both the longitudinal (MD) and width (TD) directions remains unchanged.

[0026] In one embodiment, the functional base layer formed on one side of the adhesive layer is an outer layer made of synthetic resin base material, and the functional base layer formed on the other side of the adhesive layer is a sealant layer made of sealant base material.

[0027] In one embodiment, the sealant layer is an inner layer that, after the cells are embedded, is bonded by heat to provide sealing properties, and may contain a sealing resin for heat bonding.

[0028] In one embodiment, the breaking strength in the width direction (TD) of the film is 250 N / 15 mm or less. More specifically, the breaking strength in the width direction (TD) of the film may be 150 N / 15 mm or more, 160 N / 15 mm or more, 170 N / 15 mm or more, 180 N / 15 mm or more, 190 N / 15 mm or more, 200 N / 15 mm or more, 210 N / 15 mm or more, 220 N / 15 mm or more, 230 N / 15 mm or more, 231 N / 15 mm or more; 250 N / 15 mm or less, 240 N / 15 mm or less, or 231 N / 15 mm or less, but is not limited to these values.

[0029] In one embodiment, the difference between the elongation rate in the longitudinal direction (MD) and the elongation rate in the width direction (TD) of the film is 6% or less. More specifically, the difference between the elongation rate in the longitudinal direction (MD) and the elongation rate in the width direction (TD) of the film may be 0% or more, 1% or more, 2% or more, 3% or more; 6% or less, 5% or less, 4% or less, or 3% or less, but is not limited to these values.

[0030] In one embodiment, the product of the difference (N / 15mm) between the breaking strength in the longitudinal direction (MD) and the breaking strength in the width direction (TD) of the film, and the difference (%) between the elongation rate in the longitudinal direction (MD) and the elongation rate in the width direction (TD) of the film, is 240 or less. More specifically, the product of the difference in breaking strength (N / 15mm) and the difference in elongation rate (%) may be 5 or more, 10 or more, 15 or more, 20 or more, 25 or more, 30 or more, 35 or more, 40 or more, 45 or more, 50 or more, 55 or more, 60 or more, 65 or more, 70 or more, 75 or more, 80 or more, 85 or more, 90 or more, 95 or more, 99 or more; 200 or less, 190 or less, 180 or less, 170 or less, 160 or less, 150 or less, 140 or less, 130 or less, 120 or less, 110 or less, 100 or less, or 99 or less, but is not limited to these values. When the product of the difference in breaking strength (N / 15mm) and the difference in elongation (%) falls within the aforementioned range, the cell pouch film has uniform physical properties in the longitudinal direction (MD) and the width direction (TD), which allows the stress applied to the film during the molding and processing of the cell pouch film to be uniformly distributed. This delays the phenomenon in which stress concentrates in one direction and accelerates crack formation, thereby improving moldability and durability.

[0031] In one example, the moldability of the film in both the longitudinal direction (MD) and the width direction (TD) is 16.5 mm or more. When a test piece cut from the cell pouch film is molded and its depth is measured, if no tears occur in any of the 10 pieces at that depth, a deeper depth is applied. If even one tear occurs, the depth immediately before the tear is taken as the maximum height and referred to as the moldability. More specifically, the moldability of the film in both the longitudinal direction (MD) and the width direction (TD) may be 16.5 mm or more, but is not limited to this. The molded shape of the cell pouch film is generally not a square but a rectangle (for example, a width of 190 mm and a height of 90 mm). For example, the moldability of the film in the longitudinal direction (MD) means that the molded rectangle has a width of 190 mm (TD direction) and a height of 90 mm (MD direction). The moldability in the width direction (TD) means that the formed rectangular shape has a horizontal length of 190 mm (MD direction) and a vertical length of 90 mm (TD direction).

[0032] In one embodiment, the metal constituting the barrier layer, specifically the metal thin film or metal vapor-deposited layer, may be one or more selected from the group consisting of aluminum (Al), iron (Fe), copper (Cu), nickel (Ni), tin (Sn), zinc (Zn), indium (In), and tungsten (W) (a single metal or a mixture of single metals), or two or more alloys selected from these. In one embodiment, the metal of the barrier layer is aluminum or an alloy thereof. The barrier layer is required to have properties such as barrier properties against water vapor and other gases, as well as formability. Furthermore, the barrier layer may be surface-treated with phosphoric acid or chromium for corrosion resistance.

[0033] In one embodiment, the outer layer comprises one or more resins selected from the group consisting of polyethylene terephthalate (PET) resin and nylon resin. The outer layer is required to have properties such as heat resistance, pinhole resistance, chemical resistance, abrasion resistance, moldability, and insulation. The outer layer may be composed of multiple layers. In one embodiment, the outer layer consists of polyethylene terephthalate (PET) resin and nylon resin.

[0034] In one embodiment, the sealant layer comprises one or more polyolefin resins selected from the group consisting of polypropylene, low-density polyethylene, linear low-density polyethylene, ultra-low-density polyethylene, medium-density polyethylene, high-density polyethylene, polybutene, and ethylene / propylene copolymer. The sealant layer is required to have properties such as heat resistance, cold resistance, thermal adhesion, and moldability, as well as electrolyte resistance and insulation resistance, given that it is a layer that comes into contact with the electrolyte. The sealant layer may be composed of multiple layers.

[0035] In one embodiment, the surface treatment layer may be a surface treatment layer made of phosphoric acid, chromium, zirconium, cerium, lanthanum, etc., in order to provide corrosion resistance to the metal.

[0036] In one embodiment, the adhesive layer may contain one or more of the following: epoxy adhesive, polyurethane adhesive, phenolic resin adhesive, polyester adhesive, and polyolefin adhesive. In one example, the inner adhesive layer and the outer adhesive layer may each have a thickness of 0.5 μm to 10 μm.

[0037] In one embodiment, the barrier layer may have a thickness of 5 μm to 100 μm. If the thickness of the barrier layer is less than 5 μm, it is not easy to embody it as a cell pouch for a secondary battery, and if the thickness of the barrier layer exceeds 100 μm, the battery capacity may decrease rapidly in the bending test of the cell pouch. In one embodiment, the outer layer may have a thickness of 5 μm to 50 μm. In one embodiment, the sealant layer may have a thickness of 5 μm to 100 μm.

[0038] In one embodiment, an extruded resin layer may be further formed between the inner adhesive layer and the sealant layer. The extruded resin layer can improve the flexibility, adhesion, and insulation properties of the pouch. In one embodiment, the extruded resin layer may contain an olefin resin such as a polypropylene resin. In another embodiment, the inner layer of the cell pouch film may be composed of the extruded resin layer and the sealant layer without the inner adhesive layer. If there is no inner adhesive layer as described above, the extruded resin layer may also serve the role of the inner adhesive layer. In one embodiment, the extruded resin layer may have a thickness of 5 μm to 80 μm.

[0039] Cell pouch A cell pouch film according to one embodiment of the present invention is suitable for cell pouch applications because it has excellent gas barrier properties, flexibility, electrolyte resistance, and heat adhesion.

[0040] Another exemplary embodiment of the present invention provides a cell pouch including a cell pouch film according to one embodiment of the present invention.

[0041] Method for manufacturing film for cell pouches Another exemplary embodiment of the present invention provides a method for manufacturing a cell pouch film, comprising: a double-sided surface treatment step of surface-treating both sides of a metal base material that forms a barrier layer; a single-sided surface coating step of applying an adhesive to one side of the surface-treated metal base material to form an adhesive layer; and a lamination step of laminating a functional base material to one side of the adhesive layer to form a functional base material layer.

[0042] This invention employs an in-line 1-pass 3-coating (1P3C) system, which allows for three or more coating processes to be performed in a single facility according to the manufacturing method of this invention, rather than a system that repeatedly performs coating, drying, and winding processes at each stage. This reduces the probability of running losses and process defects that occur during the feeding of the raw material. Furthermore, according to the method of this invention, the process speed is high, the number of windings is reduced, the stress applied to the film is reduced, the tension of the drive rolls that feed the film is low, which does not cause changes in the tensile curve of the film, and the mechanical strength of the film in the longitudinal (MD) and width (TD) directions does not change.

[0043] The double-sided surface treatment step is a process of surface treating both sides of a metal raw material that forms a metal layer by applying a first and second coat, and the double-sided surface treatment step is performed by a double-sided coating means including a first coater and a second coater.

[0044] The double-sided surface treatment step may include a raw material supply step of unwinding and supplying a wound metal raw material; a foreign matter removal step of removing foreign matter present on the surface of the supplied metal raw material; a tension adjustment step of adjusting the tension of the metal raw material from which the surface foreign matter has been removed; and a double-sided coating step of coating both sides of the metal raw material while maintaining a constant tension.

[0045] The aforementioned foreign matter removal process may include a first foreign matter removal process in which an electrical discharge treatment is applied to both sides of the metal raw material to remove oil. The aforementioned foreign matter removal process may further include a pinhole inspection process to check for the presence or absence of pinholes on both sides of the metal raw material from which the oil has been removed. The aforementioned foreign matter removal process may further include a second foreign matter removal process in which foreign matter generated on both sides of the metal raw material after the pinhole inspection is removed using a roll method.

[0046] One side of the metal substrate is coated with a first-stage coating using a primary coater employing both direct coating and reverse kiss coating (RKC) methods, applying water-based and solvent-based coating solutions, taking into account the properties and modifications of the coating solution. The other side of the metal substrate may be coated with a second-stage coating using RKC and film up / down coating methods. Furthermore, by configuring the system to allow adjustment of the positions of the substrate contact surface, coating roll, and doctor, it is possible to improve the uniformity of the coating and the work speed. In particular, by configuring a chamber system (sealed piping) for precise control of the coating agent, the viscosity of the coating agent can be adjusted, and the inflow of foreign matter can be basically blocked.

[0047] The process may further include a property stabilization drying step between the double-sided surface treatment step and the one-sided surface coating step for forming the adhesive layer, in which the metal raw material coated on both sides is dried in a floating manner to stabilize its physical properties; a cooling step for cooling the dried metal raw material; and a surface inspection step for inspecting the surface of the cooled metal raw material.

[0048] Once the double-sided surface treatment stage is complete, the metal raw material coated on both sides can be dried using a floating method to stabilize its physical properties. In this case, the drying method may be an air floating method, which allows the coated substrate to be dried non-contact while suspended. This makes it possible to dry the metal raw material with double-sided surface treatment while minimizing contact with components such as feed rolls. Next, after the dried metal raw material has been cooled, the surface of the cooled metal raw material may be inspected.

[0049] The one-sided surface coating step for forming the adhesive layer is a process of applying adhesive to one side of a metal substrate that has been surface-treated by two coatings, and is performed by a third coater, preparing it for lamination while going through processes such as drying. After applying the adhesive, the metal substrate to which the adhesive has been applied is dried to form the adhesive layer, and the thickness of the dried adhesive layer can be measured, and the surface of the adhesive layer can be corona-treated to enhance the adhesive strength.

[0050] One embodiment of the above method may further include an internal adhesive layer coating step, after the lamination step, in which an internal adhesive is applied to the other side of the metal raw material where the outer layer is not laminated to form an internal adhesive layer. Another embodiment may further include a drying step after the coating step. Another embodiment may further include a step of laminating a sealant layer raw material beneath the internal adhesive layer.

[0051] In one embodiment, the method may include a total of two or fewer winding steps to prevent punctures and / or indentations from occurring in the raw material used in each step up to the outer layer lamination step. Specifically, the metal raw material may have been wound a total of two or fewer times. More specifically, the winding step may include a total of one winding step. In one embodiment, the winding step may be included after the outer adhesive layer coating step and before the outer layer raw material lamination step. For example, the winding step may be performed in step (10) in Figure 2.

[0052] In one embodiment, the lamination step of laminating an outer layer base material onto the outer adhesive layer and the step of laminating a sealant layer base material below the inner adhesive layer are processes of laminating a functional base material to one side of a metal base material to which adhesive has been applied, wherein the inner side may be laminated with a sealant layer base material mainly for stabilizing the heat resistance and cold resistance of the battery, and the outer side may be laminated with an outer layer base material for heat resistance, pinhole resistance, abrasion resistance, etc. In one embodiment, each of the lamination steps may be lamination of a pre-prepared outer layer base material or sealant base material.

[0053] Between the third coating step and the lamination step, the process may further include an adhesive drying step in which the metal base material to which the adhesive has been applied is dried to form an adhesive layer; an adhesive layer thickness measuring step in which the thickness of the dried adhesive layer is measured; and an adhesive layer surface treatment step in which the surface of the adhesive layer is corona treated to enhance the adhesive strength.

[0054] The lamination step may further include a surface inspection step for inspecting the surface of the sealant layer or outer layer.

[0055] On the other hand, in the process of feeding each roll of raw material, both a tensioning structure, in which the base material contact roll and the shaft are separated and movable, and a shaft structure, in which they are integrated and movable, may be applied to the guide roll. The general drive method for guide rolls is a mechanism that transmits rotation from the motor to the shaft-integrated guide roll and drives it in a 1:1 speed ratio, whereas the tensioning drive method separates the guide roll and the shaft and mutually compensates for the rotational speed of the fine rolls, and may be applied as appropriate in the necessary sections.

[0056] Furthermore, a re-winder unit and an un-winder unit (raw material supply unit) may be configured separately so that they can be operated independently in the event of a problem with the equipment causing malfunctions in its operation.

[0057] Furthermore, this disclosure may further include a maturation step as one embodiment. The maturation step is a necessary process to improve the reliability of adhesive strength, electrolyte resistance, peel strength, etc., during the manufacture of the cell pouch, but since the required time is somewhat long, the optimal maturation process is crucial. From the standpoint of productivity, it is preferable to manufacture the product by going through only one maturation step for the final structure of the cell pouch. Specifically, the method may include one maturation step. More specifically, the method may involve applying an adhesive to one side of the surface-treated metal raw material after the double-sided surface treatment step without a maturation step, and the maturation step may be included after the sealant layer lamination step. For example, if the maturation step is included in the double-sided surface treatment step before the lamination step, desorption of the unlaminated surface treatment agent may occur while the film in the manufacturing stage is exposed to air for a certain period of time or longer. For example, if the maturation step is included in the adhesive layer formation step, a blocking phenomenon may occur where the reaction of the adhesive layer progresses partially and then the adhesive layer adheres to other layers.

[0058] The first intermediate structure of the cell pouch film may consist of an outer layer / adhesive layer / surface treatment layer / barrier layer / surface treatment layer / adhesive layer, and the second intermediate structure may consist of an outer layer / adhesive layer / surface treatment layer / barrier layer / surface treatment layer. If two maturation processes are unavoidable, it is preferable to perform the first maturation with the second intermediate structure, and then the second maturation with the final structure. If the first maturation is performed with the first intermediate structure, problems such as manufacturing process issues and deterioration of physical properties may occur. More specifically, in products that have undergone the first maturation with the first intermediate structure, the reaction of the inner adhesive layer (sealant layer side) may partially proceed, and a blocking phenomenon may occur where the inner adhesive layer adheres to the outer layer.

[0059] Furthermore, when a sealant layer is formed after primary maturation, an additional process is required to strengthen the adhesive strength of the inner bonding layer, which can lead to a decrease in productivity.

[0060] On the other hand, in order to minimize the generation of foreign matter and scratches during the feeding of the raw material, a suction roll may be applied in the tension control section, and a contact-type clean roll may be applied to remove foreign matter to prevent foreign matter generated during travel from sticking to the roll and causing defects in appearance (piercing, scratches, etc.).

[0061] In one embodiment, the film for the cell pouch is fed by a drive roll, and all or part of the drive roll is a suction roll. The suction roll has a plurality of holes to draw in air from its circumferential surface. By drawing in air through the holes, the film is attracted to the circumferential surface of the suction roll so as to come into contact with it.

[0062] In one example, the tension applied to the cell pouch film by the suction roll is 0.02 kgf / cm². 2 ~2.5 kgf / cm² 2 That is the case.

[0063] In one example, the metal roll of film for cell pouches is wound up a total of two times or less during the manufacturing process of the cell pouch film.

[0064] Manufacturing equipment for cell pouch film Another exemplary embodiment of the present invention provides a manufacturing apparatus for a cell pouch film, comprising: a double-sided surface treatment means including a first coater 3 and a second coater 4 for surface treating both sides of a metal base that forms a barrier layer; a third coater 7 for applying an adhesive to one side of the surface-treated metal base; and a laminating section 9 for laminating a functional base to one side of the adhesive layer.

[0065] Figure 2 is a schematic diagram of a manufacturing apparatus for cell pouch film according to one embodiment of the present invention.

[0066] The double-sided surface treatment means may include a raw material supply unit 1, a foreign matter removal means 2, a tension adjustment unit, and a primary coater 3 and a secondary coater 4. The raw material supply unit 1 unwinds and supplies the wound metal raw material. The foreign matter removal means 2 removes foreign matter present on the surface of the supplied metal raw material. The tension adjustment unit adjusts the tension of the metal raw material from which the surface foreign matter has been removed. The primary coater 3 and the secondary coater 4 coat both sides of the metal raw material while maintaining a constant tension.

[0067] The foreign matter removal means 2 may include a first foreign matter removal unit that removes oil by applying an electrical discharge treatment to both sides of the metal raw material. It may further include a pinhole inspection unit that checks for the presence or absence of pinholes on both sides of the metal raw material from which the oil has been removed. If no abnormalities are found as a result of the inspection, it may further include a second foreign matter removal unit that removes any foreign matter generated on both sides of the metal raw material using a roll method.

[0068] A property stabilization drying section 5 may be provided between the double-sided surface treatment means and the third coater 7 to stabilize the physical properties of the metal raw material coated on both sides by drying it in a floating manner. In this case, the drying method may be an air floating method so that the coated substrate can be dried in a non-contact manner while floating. This makes it possible to dry the double-sided coated metal raw material while minimizing contact with components such as feed rolls. Next, the dried metal raw material may be cooled by a cooling section 6, and the surface of the cooled metal raw material may be inspected by a surface inspection section.

[0069] The third coater 7 and the laminate section 9 may further include an adhesive drying section 8 for drying a metal base material coated with adhesive to form an adhesive layer; an adhesive layer measuring section for measuring the thickness of the dried adhesive layer; and an adhesive layer surface treatment section for corona treatment of the surface of the adhesive layer to enhance the adhesive strength.

[0070] The laminated portion 9 may further include a surface inspection portion for inspecting the surfaces of the sealant layer and the outer layer.

[0071] Between the laminate section 9 and the final winding section (End, 2nd Re-wind) in Figure 2, a fourth coater (not shown) for applying adhesive to the other side of the surface-treated metal raw material, a drying section (not shown), a functional layer laminate section (not shown), an extrusion section (including co-extrusion) (not shown), etc. may be added as needed. [Examples]

[0072] The present invention will be described below in detail with reference to preferred embodiments, so that it can be easily implemented by a person with ordinary skill in the art to which the invention pertains. However, the present invention can be embodied in various different forms and is not limited to the embodiments described herein.

[0073] <Manufacturing Example 1> Manufacturing of film for cell pouches Both sides of the aluminum foil base material forming the barrier layer were surface-treated by applying a first and second coating. Next, the metal base material with both sides coated was dried using a floating method to stabilize its physical properties. Then, the dried metal base material was cooled, and a urethane-based adhesive was applied to one side of the surface-treated metal base material using a third coater to form an adhesive layer. Next, a pre-prepared PET / nylon film was laminated to one side of the adhesive layer to form an outer layer. An adhesive was applied to the other side of the aforementioned adhesive layer, and an unstretched polypropylene film was laminated to form a sealant layer, thereby manufacturing and winding up a film for cell pouches (Example 1: A sample taken at 700m from the paper core on a roll totaling 2,000m; Example 2: A sample taken at 1,300m from the paper core on a roll totaling 2,000m; Example 3: A sample taken at 1,900m from the paper core on a roll totaling 2,000m).

[0074] <Manufacturing Example 2> Manufacturing of film for cell pouches One side of the aluminum foil metal roll forming the barrier layer was surface-treated with a primary coating, dried, and then wound up. The other side of the aluminum foil metal roll forming the barrier layer was surface-treated with a secondary coating, dried, and then wound up. One side of the aluminum foil metal roll with both sides surface-treated was coated with a urethane-based adhesive, dried, and then laminated with a pre-prepared PET / nylon film to form the outer layer before being wound up. Next, an inner adhesive was coated, dried, and then the inner layer (sealant film) was laminated and wound up (Comparative Example 1: A sample taken at 700m from the paper core on a roll totaling 2,000m; Comparative Example 2: A sample taken at 1,300m from the paper core on a roll totaling 2,000m; Comparative Example 3: A sample taken at 1,900m from the paper core on a roll totaling 2,000m).

[0075] <Experimental Example 1> Evaluation of the difference between the physical properties of a film in the longitudinal direction (MD) and the width direction (TD). The difference between the longitudinal (MD) and widthwise (TD) properties of the cell pouch films produced in Production Example 1 and Production Example 2 was evaluated.

[0076] More specifically, specimens measuring 130 mm x 15 mm were taken from the wound roll in both the longitudinal (MD) and widthwise (TD) directions. The tensile strength of the collected specimens was measured using a UTM (manufactured by INSTRON) universal testing machine in accordance with ASTM D638, under conditions of a stretching speed of 50 mm / min and a grip distance of 50 mm. The breaking strength, which is the strength at the point when the specimen is cut and fractured, was measured. A 30 mm mark was placed in the middle of the collected specimen, and the elongation rate was measured and evaluated by actually measuring the length that stretched after fracture.

[0077] The results are shown in Figure 3 and Tables 1 and 2 below. Figure 3 is the stress-strain curve of a cell pouch film according to one embodiment of the present invention.

[0078] [Table 1]

[0079] [Table 2]

[0080] From Figure 3 and Tables 1 and 2, it can be confirmed that the cell pouch film according to the present invention exhibits excellent mechanical strength and low deviation in mechanical strength.

[0081] <Experimental Example 2> Evaluation of the difference between the moldability of the film in the longitudinal direction (MD) and the moldability in the width direction (TD) The difference between the longitudinal (MD) and widthwise (TD) properties of the cell pouch films produced in Production Example 1 and Production Example 2 was evaluated.

[0082] More specifically, specimens measuring 266 mm x 240 mm were taken from the wound roll in both the longitudinal (MD) and widthwise (TD) directions. The collected specimens were molded into a rectangular shape (190 mm horizontally and 90 mm vertically) (moldability was evaluated in 1 cup using a chrome-coated high-moldability pouch evaluation device; R values ​​varied, but the reference corner R value was 4).

[0083] When the depth was measured after molding, if no tears occurred in any of the 10 samples at that depth, a deeper depth was applied. If even one tear occurred at this depth, the depth immediately preceding the tear was defined as the maximum height for moldability.

[0084] The moldability in the longitudinal direction (MD) means that the formed rectangular shape has a horizontal length of 190 mm (TD direction) and a vertical length of 90 mm (MD direction). The moldability in the width direction (TD) means that the formed rectangular shape has a horizontal length of 190 mm (MD direction) and a vertical length of 90 mm (TD direction). The results are shown in Table 3 below.

[0085] [Table 3]

[0086] From Table 3 above, it can be confirmed that the cell pouch film according to the present invention exhibits the best moldability.

[0087] Although exemplary embodiments of the present invention have been described above in relation to the preferred embodiments mentioned above, various modifications and variations can be made without departing from the gist and scope of the invention. Therefore, it can be said that such modifications and variations belonging to the gist of the present invention are included in the appended claims. [Explanation of Symbols]

[0088] 1: Original fabric supply section 2: Foreign matter removal means 3: First Courter 4: Second Courter 5: Physical property stabilization drying section 6: Cooling section 7: Third coater 8: Adhesive drying section 9: Laminating section 10: Final winding section 100: Outer layer 200: Outer adhesive layer 300: Barrier layer 310: Surface treatment layer 320: Metal layer 330: Surface treatment layer 400: Internal adhesive layer 500: Sealant layer

Claims

1. A barrier layer made of metal with surface treatment applied to both sides; Adhesive layers formed on both sides of the barrier layer; and The adhesive layer includes a functional raw material layer formed on both sides of the adhesive layer; A cell pouch film in which the difference between the breaking strength in the longitudinal direction (MD) and the breaking strength in the width direction (TD) is 40 N / 15 mm or less.

2. The functional base layer formed on one side of the adhesive layer is an outer layer made of synthetic resin base material, The cell pouch film according to claim 1, wherein the functional base layer formed on the other side of the adhesive layer is a sealant base layer.

3. The strong pouch film according to claim 1, wherein the breaking strength in the width direction (TD) of the film is 250 N / 15 mm or less.

4. The film for cell pouches according to claim 1, wherein the difference between the elongation rate in the longitudinal direction (MD) and the elongation rate in the width direction (TD) of the film is 6% or less.

5. The cell pouch film according to claim 1, wherein the product of the difference (N / 15mm) between the breaking strength in the longitudinal direction (MD) and the breaking strength in the width direction (TD) of the film, and the difference (%) between the elongation rate in the longitudinal direction (MD) and the elongation rate in the width direction (TD) of the film is 240 or less.

6. The cell pouch film according to claim 1, wherein the moldability in both the longitudinal direction (MD) and the width direction (TD) of the film is 16.5 mm or more.

7. The metal of the barrier layer is aluminum or an alloy thereof. The outer layer comprises one or more resins selected from the group consisting of polyethylene terephthalate resin and nylon resin. The film for cell pouches according to claim 2, wherein the sealant layer comprises one or more polyolefin resins selected from the group consisting of polypropylene, low-density polyethylene, linear low-density polyethylene, ultra-low-density polyethylene, medium-density polyethylene, high-density polyethylene, polybutene, and ethylene / propylene copolymer.

8. A cell pouch comprising a cell pouch film according to any one of claims 1 to 7.

9. A double-sided surface treatment step in which surface treatment is applied to both sides of the metal raw material that forms the barrier layer; A one-sided surface coating step in which an adhesive is applied to one side of the metal raw material that has undergone the aforementioned surface treatment to form an adhesive layer; and A method for manufacturing a cell pouch film according to any one of claims 1 to 7, comprising a lamination step of laminating a functional raw material to one side of the adhesive layer to form a functional raw material layer.

10. The method for manufacturing a cell pouch film according to claim 9, wherein the feeding of the cell pouch film is performed by a drive roll, and all or part of the drive roll is a suction roll.

11. The tension applied to the cell pouch film by the suction roll is 0.02 kgf / cm². ２ ~2.5kgf / cm ２ The method for manufacturing a cell pouch film according to claim 10.

12. The method for manufacturing a cell pouch film according to claim 10, wherein in the manufacturing process of the cell pouch film, the metal roll of the cell pouch film is wound up a total of two times or less.

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