Cell pouch film and its storage method

Abstract

To provide a film for a cell pouch having excellent formability and reduced leakage of a slip agent, and a storage method thereof.SOLUTION: A film for a cell pouch includes: a sealant layer including a slip agent; a metal layer formed on the sealant layer; and an outer layer formed on the metal layer. When the film is stored for 30 days at a temperature of 48 to 57°C and then the outer surface of a black pouch is rubbed with the sealant layer or outer layer of the film at a speed of 400 mm / 10 s using a slip inspection device in which a 1.3 kgf cube-shaped metal is wrapped in a black pouch with a matte black exterior and an outer layer made of nylon, the surface roughness of the portion where the slip agent leaking from the film oozes and forms a white band on the black pouch satisfies Rt 13 to 20 μm and Rz 10 to 15 μm.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present specification relates to a film for a cell pouch and a method for storing the same.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority based on Korean Patent Application No. 10-2023-0066379, filed on May 23, 2023, the entire contents of which are incorporated herein by reference. This application claims priority based on Korean Patent Application No. 10-2024-0061080, filed on May 9, 2024, the entire contents of which are incorporated herein by reference.

[0003] State-sponsored research and development explanation This research was carried out through the following national projects: - Department name: Ministry of Trade, Industry and Energy, Project management (specialized) organization name: Korea Institute for Industrial Technology Evaluation and Management, Research project name: Material parts packaging type (best company), Research project name: Development of next-generation secondary battery pouch that can realize more than twice the high adhesive strength (60℃), Project implementation organization name: Yurimura Chemical Co., Ltd., Project number: 20022450, Project unique number: 1415185612 [Background technology]

[0004] Pouch-type batteries, commonly used in electric vehicles, offer advantages over cylindrical or prismatic batteries, including easier reshaping and higher energy density. Cell pouches are the outer packaging material that encases the battery's electrodes and electrolyte. They must meet a variety of requirements, including interlayer adhesion between the metal thin film and polymer, heat seal strength, electrolyte resistance, airtightness, moisture permeability, and formability. In particular, cell pouches must possess high formability for use in large batteries, such as those used in electric vehicles (EVs) and energy storage systems (ESSs). To this end, cell pouches require a slip agent as an additive to improve formability. The slip agent migrates to the outermost layer of the pouch depending on the temperature and pressure after manufacturing, providing formability. However, excessive slip agent migrates, causing process contamination and a sharp decline in process efficiency due to the aggregation of slip agent particles. Therefore, there is a need for a cell pouch film that can prevent slip agent aggregation and provide high formability. Summary of the Invention [Problem to be solved by the invention]

[0005] The problem to be solved by the present disclosure is to provide a cell pouch film that has excellent formability and reduced slip agent leakage, and a method for storing the same. [Means for solving the problem]

[0006] One embodiment of the present disclosure includes a sealant layer comprising a slip agent; a metal layer formed on the sealant layer; and an outer layer formed on the metal layer; A film for a cell pouch comprising: The film is stored at a temperature of 48 to 57°C for 30 days, and then, when a lubricant testing device is used to rub the front surface of a 1.3 kgf cubic metal piece with a matte black exterior and a nylon outer layer against the sealant layer or outer layer of the film at a speed of 400 mm / 10 s, the slip agent that has leaked out of the film and exuded white streaks on the black pouch has a surface roughness of Rt 13 to 20 μm and Rz 10 to 15 μm.

[0007] Another embodiment of the present disclosure provides a cell pouch including the cell pouch film.

[0008] Another embodiment of the present disclosure provides a method for storing the cell pouch film described in any one of the above aspects, the method including a step of storing the film at a temperature of 48 to 57°C. [Effects of the Invention]

[0009] According to one embodiment of the present disclosure, by adjusting the storage temperature after manufacturing of a cell pouch film, it is possible to minimize the phenomenon of excessive slip agent flowing to the surface even when a small amount of slip agent is contained, thereby improving the efficiency of the slip agent. Therefore, the film according to the present disclosure exhibits excellent formability and prevents excessive slip agent flow, thereby preventing process defects due to the slip agent. [Brief explanation of the drawings]

[0010] [Figure 1] 1 shows the results of measuring the surface roughness of Examples 1 and 2 and Comparative Example 4 in Test Example 1. [Figure 2] 1 is an image of the lubricant inspection device used in Test Example 2. [Figure 3] 10 is an image of the black pouch after the lubricant test in Test Example 2. [Figure 4] FIG. 1 is a diagram showing the evaluation criteria (grades S, A, and B) for the lubricant inspection in Test Example 2. [Figure 5A] 1 shows the results of particle size analysis of particles formed by agglomeration of slip agent in Example 1 (storage temperature 50°C) after lubricant testing in Test Example 2 (80x magnification). [Figure 5B] 1 shows the results of particle size analysis of particles formed by agglomeration of slip agent in Example 1 (storage temperature 50°C) after lubricant testing in Test Example 2 (450x magnification). [Figure 6A] 1 shows the results of particle size analysis of particles formed by aggregation of slip agent in Comparative Example 4 (storage temperature 45°C) after lubricant testing in Test Example 2 (80x magnification). [Figure 6B] 1 shows the results of particle size analysis of particles formed by aggregation of slip agent in Comparative Example 4 (storage temperature 45°C) after lubricant testing in Test Example 2 (450x magnification). DETAILED DESCRIPTION OF THE INVENTION

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0012] The embodiments of the present disclosure disclosed herein are merely illustrative and are not to be construed as being limited to the embodiments described herein, as the present disclosure may be embodied in various forms. The present disclosure can be modified in various ways and can take various forms. The embodiments are not intended to limit the present disclosure to the specific disclosed forms, but should be understood to include all modifications, equivalents, and alternatives within the spirit and technical scope of the present disclosure.

[0013] The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and do not exclude the presence or additional possibility of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0014] In this specification, the term "cell" refers to a battery, and has the broadest meaning including all types of batteries such as secondary batteries such as lithium ion batteries and lithium polymer batteries, and portable storage batteries.

[0015] In this specification, the term "cell pouch" has the broadest meaning, including all laminated films processed into a bag or box shape to accommodate cell components such as a positive electrode, a negative electrode, and a separator, which are impregnated with an electrolyte and housed therein, taking into consideration gas barrier properties, bendability, electrolyte resistance, thermal adhesiveness, etc.

[0016] As used herein, "formability" refers to the ability of a cell pouch film to be processed into a desired shape without cracking or tearing and to maintain that shape. For example, formability can be evaluated by measuring the maximum depth at which a cell pouch film can be cut into a test piece and formed into a cup shape under a pressure of 0.3 MPa. More specifically, if none of ten test pieces of the same film are broken, the next deeper depth is applied. If even one test piece breaks, the depth immediately preceding that break is defined as the maximum height. For example, formability can be evaluated using a rectangular parallelepiped forming cup (opening size: 16 cm x 9 cm). More specifically, formability can be evaluated using the GS-S5 model manufactured by Gwangshin Hi-Tech Co., Ltd.

[0017] One embodiment of the present disclosure provides a film for a cell pouch, the film including a sealant layer, a metal layer formed on the sealant layer, and an outer layer formed on the metal layer, wherein the sealant layer contains a slip agent; and after storing the film at a temperature of 48 to 57°C for 30 days, when a front surface of a 1.3 kgf cubic metal piece wrapped in a black pouch having a matte black exterior and an outer layer made of nylon is rubbed against the sealant layer or the outer layer of the film at a speed of 400 mm / 10 s using a lubricant testing device, the front surface of the black pouch being rubbed against the sealant layer or the outer layer of the film at a speed of 400 mm / 10 s, the slip agent leaked from the film and oozed out, forming white streaks on the black pouch, the surface roughness of the portion satisfying Rt 13 to 20 μm and Rz 10 to 15 μm.

[0018] According to one embodiment of the present disclosure, the film may be stored at a temperature of 48 to 57°C, and adjusting the storage temperature can prevent excessive slip agent leakage and aggregation. Specifically, the storage temperature may be 48°C or higher, 49°C or higher, 50°C or higher, 51°C or higher, 52°C or higher, 53°C or higher, or 54°C or higher, and 57°C or lower, 56°C or lower, 55°C or lower, 54°C or lower, 53°C or lower, 52°C or lower, or 51°C or lower. Storage temperatures above 57°C may result in reduced moldability, while temperatures below 48°C may result in excessive slip agent leakage and aggregation, causing process defects and reducing product reliability.

[0019] In one embodiment, the storage period may be 10 to 300 days. Specifically, the storage period may be 10 days or more, 20 days or more, 30 days or more, 40 days or more, 50 days or more, 60 days or more, 70 days or more, 80 days or more, 90 days or more, 100 days or more, 150 days or more, 200 days or more, or 250 days or more, and may be 300 days or less, 200 days or less, 100 days or less, 90 days or less, 80 days or less, 70 days or less, 60 days or less, 50 days or less, 40 days or less, 30 days or less, 20 days or less, or 10 days or less.

[0020] In one embodiment, the relative humidity during storage may be 5% to 25%. In this disclosure, the term "relative humidity (RH)" refers to the ratio, expressed as a percentage (%), of the amount of water vapor currently contained in the air to the maximum saturated water vapor pressure that a given volume of air can contain.

[0021] In one embodiment, the surface roughness of the film is a parameter representing the state in which the slip agent contained in the sealant layer of the film flows into the sealant layer and the outer layer and partially aggregates. In this disclosure, the surface roughness refers to the degree of fine irregularities present on the surface. Among the surface roughness parameters, Rt is the maximum height roughness, measured as the vertical distance between two parallel lines parallel to the center line of the roughness curve within the cut-off length of the extracted portion, passing through the highest and lowest points of the curve. Rz is the ten-point median height, measured as the distance between the average height of the five largest peaks and the average depth of the five largest valleys.

[0022] In one embodiment, the black pouch used in the surface roughness measurement had a matte black appearance and an outer layer made of nylon (manufactured by Kurimura Chemical Co., Ltd.). When the black pouch was rubbed, friction occurred between the front surface of the black pouch and the sealant layer or outer layer of the film, causing slip agent to bleed out from the film and form white streaks on the front surface of the black pouch. The present disclosure has discovered that when the film containing slip agent in the sealant layer exhibits the above-described surface texture range, a small amount of slip agent bleeds out, resulting in small aggregate particle sizes and high moldability. From this perspective, the surface roughness of the area where white streaks are formed, when measured by the above-described method, may satisfy Rt 13 to 20 μm and Rz 10 to 15 μm. Here, the surface roughness may be measured when the sealant layer is rubbed once or the outer layer is rubbed five times in the same direction. Specifically, the surface roughness Rt (μm) may be 13 or more, 14 or more, 15 or more, 16 or more, 17 or more, 18 or more, or 19 or more, and 20 or less, 19 or less, 18 or less, 17 or less, 16 or less, 15 or less, or 14 or less. The surface roughness Rz (μm) may be 10 or more, 11 or more, 12 or more, 13 or more, or 14 or more, and 15 or less, 14 or less, 13 or less, 12 or less, or 11 or less. Films with surface roughness Rt and Rz outside the above ranges may exhibit excessive slip agent leakage during a lubricant test, resulting in the presence of agglomerated particles larger than 60 μm on the surface of the sealant layer, and the sealant layer may exhibit a low coefficient of friction or formability.

[0023] In one aspect, the film according to one embodiment may be stored at a temperature of 48 to 57°C for 30 days, and then, when the front surface of a black pouch of the lubricant testing device is rubbed against the sealant layer or outer layer of the film at a speed of 400 mm / 10 s using the same lubricant testing device described above, the average diameter of the largest agglomerated particles of slip agent present in the area where the slip agent has leaked out of the film and formed white streaks on the black pouch may be 60 μm or less. Here, the agglomerated particles of slip agent refer to particles formed by agglomeration of the leaked slip agent. The more slip agent leaks out, the larger the particle size. The largest agglomerated particle of the slip agent agglomerated particles refers to the largest agglomerated particle among the formed agglomerated particles, and the average diameter refers to the average diameter measured for a single agglomerated particle. Specifically, the largest agglomerate particle size of the slip agent may refer to the largest agglomerate particle size among the agglomerate particles of 100% or less, 98% or less, 96% or less, 94% or less, 92% or less, 90% or less, 88% or less, 86% or less, 84% or less, 82% or less, or 80% or less of the total agglomerate particles of the slip agent. Alternatively, the largest agglomerate particle size of the slip agent may refer to the largest agglomerate particle size among the agglomerate particles contained in an image taken with a scanning electron microscope (SEM). Here, the agglomerate particle size of the slip agent may be measured when the sealant layer is rubbed once or the outer layer is rubbed five times in the same direction. More specifically, the agglomerate particle size of the slip agent may be 60 μm or less, 50 μm or less, or 40 μm or less. In one embodiment, the agglomerate particle size can be determined from a microscope image.

[0024] In one aspect, the film according to one embodiment may have a formability of 15 to 25 mm after storage for 30 days at a temperature of 48 to 57°C. Here, the formability is measured by applying a pressure of 0.3 MPa to the film and forming it into a cup (16 cm x 9 cm) without tearing, measuring the maximum depth. More specifically, the formability may be 15 mm or more, 16 mm or more, 17 mm or more, 18 mm or more, 19 mm or more, 20 mm or more, 21 mm or more, 22 mm or more, or 23 mm or more, and may be 25 mm or less, 24 mm or less, 23 mm or less, 22 mm or less, 21 mm or less, or 20 mm or less.

[0025] In one aspect, the film according to one embodiment may have a coefficient of friction of 0.15 to 0.5 when the coefficient of friction is evaluated after storing the film according to one embodiment at a temperature of 48 to 57°C for 30 days as follows: (a) After manufacturing a cell pouch using the film according to one embodiment of the present disclosure, the cell pouch is cut to a size of 200 mm x 100 mm to prepare a test piece, and the test piece is flatly attached to the bottom of a friction coefficient measuring device. (b) Next, a 70 mm x 60 mm test piece of the same cell pouch is fixed to a friction coefficient measuring jig. (c) Next, the jig provided in the friction coefficient measuring device is sandwiched between the two pouches so that it abuts both pouches, and the bottom of the friction coefficient measuring device is moved at a speed of 15 mm / s for 55 seconds to measure the coefficient of friction between the sealant layers of the pouches. In one embodiment, the friction coefficient measuring device may be a CF-800XS model manufactured by Labsink. Specifically, the friction coefficient may be 0.15 or more, 0.2 or more, 0.25 or more, or 0.3 or more, and may be 0.5 or less, 0.4 or less, 0.35 or less, 0.3 or less, 0.25 or less, or 0.2 or less.

[0026] In the present disclosure, the material and thickness of each layer of the film are not particularly limited as long as they can be produced as a film for a cell pouch, and may include, for example, the following configurations.

[0027] In the present disclosure, the sealant layer refers to an inner layer that is thermally bonded to provide sealing properties after the cells are installed. In one embodiment, the sealant layer may include a thermal adhesive resin, i.e., a sealing resin for thermal adhesion. Specifically, the sealant layer may include at least one selected from the group consisting of polyolefins such as polypropylene (PP) and polyethylene (PE), their copolymers, terpolymers, or derivatives thereof, and ethylene vinyl acetate (EVA). Examples of the copolymer or terpolymer include ethylene / propylene copolymers and ethylene / propylene / butadiene terpolymers. In one embodiment, the sealant layer may have a thickness of 20 μm to 100 μm. The sealant layer may be composed of multiple layers.

[0028] In this disclosure, the slip agent refers to an additive that reduces the coefficient of friction on the surface of a film and provides lubricity and moldability. In one embodiment, the slip agent may include one or more of a wax-based, an amide-based, a siloxane, and a silicone. Specifically, the slip agent may be an oleic acid amide-based slip agent. More specifically, the slip agent may include one or more of erucamide, behenamide, stearamide, and oleamide.

[0029] In one embodiment, the film may include 0.1 to 20 wt % of a slip agent based on the total weight of the sealant layer. Specifically, the film may contain at least 0.1 wt %, at least 0.2 wt %, at least 0.3 wt %, at least 0.4 wt %, at least 0.5 wt %, at least 0.6 wt %, at least 0.7 wt %, at least 0.8 wt %, at least 0.9 wt %, at least 1 wt %, at least 2 wt %, at least 3 wt %, at least 4 wt %, at least 5 wt %, at least 6 wt %, at least 7 wt %, at least 8 wt %, at least 9 wt %, at least 12 wt %, at least 15 wt %, at least 17 wt %, or at least 19 wt %, and at most 20 wt %, at most 17 wt %, at most 15 wt %, at most 13 wt %, at most 10 wt %, at most 9 wt %, at most 8 wt %, at most 7 wt %, at most 6 wt %, at most 5 wt %, at most 4 wt %, at most 3 wt %, at most 2 wt %, at most 1 wt %, or at most 0.5 wt % of the slip agent, based on the total weight of the sealant layer. If the amount of slip agent is excessively increased beyond the above range, the sealing strength may be reduced, the winding state may be poor, and the physical properties may become non-uniform over time. Also, if the amount of slip agent is less than the above range, the moldability may be reduced.

[0030] In the present disclosure, the outer layer means a layer having heat resistance, abrasion resistance, chemical resistance, etc. to protect the metal layer. In one embodiment, the outer layer may include one selected from the group consisting of polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), polyhydroxy aldehyde (PHA), polylactic acid (PLA), thermoplastic starch (TPS), polyvinyl alcohol (PVA), polycaprolactam (PCL), polyethylene (PE), polypropylene (PP), ethylene vinyl acetate (EVA), ethylene vinyl alcohol (EVOH), polyvinylidene chloride (PVDC), polyethylene terephthalate (PET), and nylon. More specifically, the outer layer may include one or more resins selected from nylon resin, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), etc. In one embodiment, the outer layer may have a thickness of 5 μm to 40 μm. The outer layer may be composed of multiple layers.

[0031] In this specification, the metal layer refers to a barrier layer that blocks water vapor or air from outside the battery, gas generated inside the battery, and / or moisture. In one embodiment, the metal layer may further include a surface treatment layer uniformly coated on one or both sides. In one embodiment, the metal layer may be a thin metal film or a metal deposition layer. An example of the thin metal film is metal foil. The metal deposition layer may be formed by vacuum-depositing a metal on a separate plastic film, such as a film of polyethylene terephthalate (PET), polyethylene (PE), or polypropylene (PP).

[0032] In one embodiment, the metal of the metal layer is not particularly limited as long as it has the above-described barrier properties. Examples include one or more (single metal or mixture of single metals) selected from the group consisting of aluminum (Al), iron (Fe), copper (Cu), magnesium (Mg), nickel (Ni), tin (Sn), zinc (Zn), indium (In), and tungsten (W), or an alloy of two or more selected from these metals. Specifically, the metal may include one or more selected from the group consisting of aluminum or its alloys, titanium or its alloys, tungsten or its alloys, molybdenum or its alloys, copper or its alloys, and stainless steel. More specifically, it may include aluminum. In one embodiment, the surface treatment layer may be a surface treatment layer containing phosphate, chromium, zirconium, cerium, lanthanum, scandium, yttrium, or the like to provide corrosion resistance to the metal.

[0033] In one embodiment, the metal layer may have a thickness of 20 μm to 80 μm. If the thickness of the metal layer is less than 20 μm, pinholes, microcracks, etc. may occur during processes such as molding, making it difficult to ensure safety. If the thickness of the metal layer is more than 80 μm, the energy density may be reduced during battery fabrication.

[0034] An embodiment of the present disclosure may further include an adhesive layer between the metal layer and the outer layer for bonding the metal layer and the outer layer. Also, an embodiment of the present disclosure may further include an adhesive layer between the sealant layer and the metal layer for bonding the metal layer and the sealant layer. Specifically, the adhesive layer may be an adhesive layer and / or an extruded resin layer. For example, the adhesive layer may include one or more of an epoxy-based adhesive, a polyurethane-based adhesive, a phenolic resin-based adhesive, a polyolefin-based adhesive, and a polyester-based adhesive. In one embodiment, the adhesive layer may have a thickness of 0.5 μm to 10 μm. For example, the extruded resin layer may include an olefin-based resin such as a polypropylene-based resin. In one embodiment, the extruded resin layer may have a thickness of approximately 5 μm to 80 μm.

[0035] One embodiment of the present disclosure can provide a cell pouch including the above-described cell pouch film.

[0036] Another embodiment of the present disclosure may provide a method for storing the aforementioned cell pouch film, including storing the film at a temperature of 48 to 57° C. Specifically, the storage temperature may be 48° C. or higher, 49° C. or higher, 50° C. or higher, 51° C. or higher, 52° C. or higher, 53° C. or higher, or 54° C. or higher, and may be 57° C. or lower, 56° C. or lower, 55° C. or lower, 54° C. or lower, 53° C. or lower, 52° C. or lower, or 51° C. or lower. Storage temperatures above 57° C. may result in reduced moldability, while temperatures below 48° C. may result in excessive leakage and aggregation of the slip agent, causing process defects and reducing product reliability.

[0037] In one embodiment, the storage period of the storage step may be 10 days or more, specifically 10 days or more, 20 days or more, 30 days or more, 40 days or more, 50 days or more, 60 days or more, 70 days or more, 80 days or more, 90 days or more, 100 days or more, 150 days or more, 200 days or more, or 250 days or more, and may be 300 days or less, 200 days or less, 100 days or less, 90 days or less, 80 days or less, 70 days or less, 60 days or less, 50 days or less, 40 days or less, 30 days or less, or 20 days or less.

[0038] In one embodiment, the relative humidity during the storage stage may be 5% to 25%.

[0039] The present disclosure will be described in more detail below through examples. However, it will be obvious to those skilled in the art that these examples are merely for the purpose of illustrating the disclosure and should not be construed as limiting the scope of the present disclosure.

[0040] [Manufacturing example] An example of the present disclosure was prepared by the following method.

[0041] A 25 μm outer layer of polyethylene terephthalate film was formed on one side of a 60 μm thick metal layer made from a metal roll of aluminum foil, and an 80 μm sealant layer was formed by laminating an unstretched polypropylene film containing an amide-based slip agent in an amount of 0.1 to 20 wt % based on the total weight of the sealant layer on the other side of the metal layer, to produce a film for a cell pouch.

[0042] As an example of the present disclosure, a film for a cell pouch can be manufactured using an outer layer in which a 12 μm polyethylene terephthalate film and a 25 μm nylon film are laminated to the outer layer, and it was confirmed that the results of the test examples described below were the same in this case as well.

[0043] [Test Example 1] In order to confirm the surface roughness of the films produced in the above Production Examples depending on the storage temperature during storage, the following experiment was carried out.

[0044] First, a lubricant testing device was prepared by wrapping the surface of a cubic metal (iron) (weight: approximately 1.3 kg) in a black pouch (manufacturer: Kurimura Chemical Co., Ltd.). The film produced in the above manufacturing example, cut to a size of 50 mm x 240 mm, was fixed on a flat surface with the sealant layer facing upward, and the black pouch of the device was rubbed once against the sealant layer of each film stored at different storage temperatures at a speed of 400 mm / 10 s. Next, a 1 x 1 cm area was measured to determine the area where the slip agent had leaked out of the film and formed white stripes on the black pouch. 2 The specimen was cut to the size of 10 mm and attached flat to a glass slide using double-sided tape. The surface roughness was then measured using a surface roughness measuring device (e.g., NV-2200 3D profiler, manufactured by Nano Systems) and an analysis program (NanoMap, manufactured by Nano Systems).

[0045] Of these, the results of Examples 1 and 2 and Comparative Example 4 are shown in FIG.

[0046] [Table 1]

[0047] As shown in the above results, it can be confirmed that in Examples 1 and 2 of the present disclosure, the surface roughness Rt falls within the range of 13 to 20 μm and the surface roughness Rz falls within the range of 10 to 15 μm by adjusting the storage temperature.

[0048] [Test Example 2] In order to confirm the cohesion state, friction coefficient, and formability of the slip agent depending on the surface roughness of the film according to one embodiment of the present disclosure, the following experiments were conducted on Examples 1 and 2 and Comparative Examples 1 to 4, whose surface roughness was confirmed in Test Example 1 above, and the measured values ​​are shown in Tables 2 to 9. The formability, lubricant test, and friction coefficient of each film were measured at room temperature on day 0, and then the results were observed while storing the film at each set storage temperature for 90 days.

[0049] Lubricant Inspection The lubricant test was conducted to measure the amount and agglomeration state of slip agent leaked onto the surface of the sealant layer or outer layer of the cell pouch film. The same lubricant tester as used for the surface roughness measurement was used. The prepared films were cut into 50 mm x 240 mm pieces and fixed on a flat surface with the sealant layer or outer layer facing upward. The test was then rubbed against the sealant layer or outer layer of each prepared film at a speed of 400 mm / 10 s. The test was repeated once for the sealant layer and five times for the outer layer. Next, images of the areas where the slip agent leaked from each film and formed white streaks on the black pouch were taken using a scanning electron microscope (SEM, manufactured by Hitachi, product name: SU3500), and the size of the slip agent agglomerated particles was confirmed and evaluated by scanning visual inspection. Figure 2 is a photograph of the lubricant inspection device used in the experiment, and Figure 3 is an image of the black pouch after the experiment, showing the formation of a white stripe at the top of the black pouch. As shown in Figure 4, visual evaluation results were graded as follows: a white stripe was observed on only one edge and there were few scratches over the majority of the area, an S grade was given; two lines were observed on the edge (white stripe area) and scratches on the slip agent were given an A grade (A+, A0, or A-); and two lines were observed on the corners and slip agent was applied over the entire surface, a B grade was given.

[0050] In addition, during SEM image analysis, the largest agglomerated particles of slip agent present in the area where the slip agent had leaked out and formed white stripes on the black pouch were selected, and the number and average diameter of the largest agglomerated particles were determined.

[0051] Measurement of the coefficient of friction Each film was cut to a size of 200 x 100 mm, and the coefficient of friction of each film was measured using a friction coefficient tester (manufacturer: Labsink, product name: CF-800XS). Specifically, a 200 x 100 mm specimen of each film was prepared and attached flat to the bottom of the friction coefficient tester. A 70 x 60 mm specimen of the same film was then attached to a jig installed in the friction coefficient tester, and the jig was then connected to the equipment with a string. The jig was placed on the equipment so that the two films were in contact, and the bottom of the equipment was moved at a speed of 15 mm / s for 55 seconds. During this time, the films on the jig, fixed with the string, did not move, and the coefficient of friction between the two films was measured.

[0052] Formability measurement Each film was cut into a size of 200 x 100 mm and placed in a cup-shaped mold (manufacturer: GWANGSHIN HI-TECH, model: GS-S5) and molded into a cup shape under a pressure of 0.3 MPa. The maximum depth at which no cracks or tears occurred during molding was measured. If no tears occurred in any of the ten film specimens, the next deeper depth was used. If even one specimen broke, the depth immediately before the break was defined as the maximum height.

[0053] Comparative Example 1 [Table 2]

[0054] Comparative Example 2 [Table 3]

[0055] Comparative Example 3 [Table 4]

[0056] Comparative Example 4 [Table 5]

[0057] Example 1 [Table 6]

[0058] Example 2 [Table 7]

[0059] Comparative Example 5 [Table 8]

[0060] Figures 5A, 5B, 6A, and 6B show the results of particle size analysis of particles formed by agglomeration of slip agent that leaked out after the lubrication test. Figures 5A and 5B are images of the film of Example 1 in the table, and the average diameter of the largest agglomerated particles present in the SEM image was 39.2 μm. Figures 6A and 6B are images of the film of Comparative Example 4 in the table. The average diameter of the largest agglomerated particles present in the SEM image of Comparative Example 4 in Figure 6A was 40.9 μm, and the average diameter of the largest agglomerated particles present in the SEM image of Comparative Example 4 in Figure 6B was 97.5 μm.

[0061] The results are summarized in the table below.

[0062] [Table 9]

[0063] As can be seen from the above results, unlike Comparative Examples 1 to 4, Examples 1 and 2 of the present disclosure satisfied the surface roughness Rt range of 13 to 20 μm and Rz range of 10 to 15 μm, and thus the size of agglomerated particles of slip agent present on the surface of the sealant layer during the lubrication test was reduced to 60 μm or less. Furthermore, Examples 1 and 2 maintained the friction coefficient of the sealant layer at 0.15 or higher, and the moldability improved by approximately 40% compared to room temperature (day 0), demonstrating excellent moldability despite a small amount of slip agent leakage.

[0064] [Test Example 3] Films were produced according to the above-mentioned Production Examples, and by adjusting the storage temperature, Examples 3 and 4 were prepared, in which the film surface roughness Rt was within the range of 13 to 20 μm and the film surface roughness Rz was within the range of 10 to 15 μm, and Comparative Examples 5 to 8, in which the film surface roughness was outside the range. To confirm the cohesion state, coefficient of friction, and moldability of the slip agent depending on the film surface roughness, the surface roughness, lubricant test, coefficient of friction, and moldability of each film were measured using the same methods as those described in Test Examples 1 and 2. The measured values ​​are shown in Table 10.

[0065] [Table 10]

[0066] As a result, Examples 3 and 4 of the present disclosure, which had a surface roughness Rt of 13 to 20 and an Rz of 10 to 15, both received an S grade in the lubricant test and exhibited a high coefficient of friction of 0.2 or more. Furthermore, although Examples 3 and 4 contained the same amount of slip agent as Comparative Examples 5 to 8, it was confirmed that the outflow of slip agent was adjusted to satisfy the surface roughness requirements, resulting in significantly superior formability.

[0067] The present disclosure can provide the following embodiment as an example.

[0068] [First embodiment] a sealant layer containing a slip agent; a metal layer formed on the sealant layer; and an outer layer formed on the metal layer; A film for a cell pouch comprising: The film is a cell pouch film, and after storing the film at a temperature of 48 to 57°C for 30 days, when a lubricant testing device is used to rub the front surface of a 1.3 kgf cubic metal piece wrapped in a black pouch with a matte black exterior and an outer layer made of nylon against the sealant layer or outer layer of the film at a speed of 400 mm / 10 s, the slip agent that has leaked out of the film and exuded white streaks on the black pouch has a surface roughness of Rt 13 to 20 μm and Rz 10 to 15 μm.

[0069] [Second embodiment] The film according to the first embodiment, wherein after storing the film at a temperature of 48 to 57°C for 30 days, when a lubricant testing device is used to rub the front surface of a 1.3 kgf cubic metal pouch with a matte black exterior and an outer layer made of nylon against the sealant layer or outer layer of the film at a speed of 400 mm / 10 s, the slip agent leaked from the film and exuded white streaks on the black pouch, and the largest agglomerated particles of the slip agent present in the area have an average diameter of 60 μm or less.

[0070] [Third embodiment] The film according to the first or second embodiment, wherein the friction coefficient of the sealant layer after storage at a temperature of 48 to 57°C for 30 days is 0.15 to 0.5.

[0071] [Fourth embodiment] The film has a formability of 15 to 25 mm after storage at a temperature of 48 to 57°C for 30 days, Here, the formability is measured by applying a pressure of 0.3 MPa to the film and measuring the maximum depth at which the film does not tear when molded into one cup, according to any one of the first to third embodiments.

[0072] [Fifth embodiment] The film according to any one of the first to fourth embodiments, wherein the film is intended to be stored at a temperature of 48 to 57°C.

[0073] [Sixth embodiment] The film according to any one of the first to fifth embodiments, wherein the film contains 0.1 to 20% by weight of a slip agent relative to the total weight of the sealant layer.

[0074] [Seventh embodiment] The film according to any one of the first to sixth embodiments, wherein the slip agent includes one or more of a wax-based agent, an amide-based agent, a siloxane agent, and a silicone agent.

[0075] [Eighth embodiment] The film according to any one of the first to seventh embodiments, wherein the metal layer contains one or more selected from the group consisting of aluminum or an alloy thereof, titanium or an alloy thereof, tungsten or an alloy thereof, molybdenum or an alloy thereof, copper or an alloy thereof, and stainless steel.

[0076] [Ninth embodiment] The film according to any one of the first to eighth embodiments, wherein the outer layer comprises one selected from the group consisting of polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), polyhydroxy aldehyde (PHA), polylactic acid (PLA), thermoplastic starch (TPS), polyvinyl alcohol (PVA), polycaprolactam (PCL), polyethylene (PE), polypropylene (PP), ethylene vinyl acetate (EVA), ethylene vinyl alcohol (EVOH), polyvinylidene chloride (PVDC), polyethylene terephthalate (PET), and nylon.

[0077] [Tenth embodiment] The film according to any one of the first to ninth embodiments, wherein the sealant layer contains a thermal adhesive resin.

[0078] [Eleventh embodiment] A method for storing the cell pouch film according to any one of the first to tenth embodiments, A storage method comprising storing the film at a temperature of 48 to 57°C.

[0079] [Twelfth embodiment] The storage method according to the eleventh embodiment, wherein the storage period of the above steps is 10 to 300 days.

[0080] [Thirteenth embodiment] The storage method according to the eleventh or twelfth embodiment, wherein the relative humidity during storage in the step is 5% to 25%.

Claims

1. A sealant layer comprising an amide-based slip agent; a metal layer formed on the sealant layer; and an outer layer formed on the metal layer; A film for a cell pouch comprising: The amide-based slip agent is contained in an amount of 0.1 to 20% by weight based on the total weight of the sealant layer; The film is intended for storage at a temperature of 48-57°C; The film is stored at a temperature of 48 to 57°C for 30 days, and then, when a lubricant testing device is used to rub the front surface of a 1.3 kgf cubic metal piece wrapped in a black pouch with a matte black exterior and an outer layer made of nylon against the sealant layer or outer layer of the film at a speed of 400 mm / 10 s, the slip agent that has leaked out of the film and exuded white streaks on the black pouch has a surface roughness of Rt 13 to 20 μm and Rz 10 to 15 μm.

2. 10. The film of claim 1, wherein, after storing the film at a temperature of 48 to 57°C for 30 days, when a lubricant testing device is used to rub the front surface of a 1.3 kgf cubic metal pouch having a matte black exterior and an outer layer made of nylon against the sealant layer or outer layer of the film at a speed of 400 mm / 10 s, the average diameter of the largest agglomerated particles of slip agent present in the area where the slip agent has oozed out of the film and formed white streaks on the black pouch is 60 μm or less.

3. 10. The film of claim 1, wherein the sealant layer has a coefficient of friction of 0.15 to 0.5 after storage at a temperature of 48 to 57°C for 30 days.

4. The film has a formability of 15 to 25 mm after storage at a temperature of 48 to 57°C for 30 days; The film according to claim 1, wherein the formability is measured by applying a pressure of 0.3 MPa to the film and measuring the maximum depth at which the film does not break when molded into one cup.

5. 2. The film of claim 1, wherein the metal layer comprises at least one selected from the group consisting of aluminum or an alloy thereof, titanium or an alloy thereof, tungsten or an alloy thereof, molybdenum or an alloy thereof, copper or an alloy thereof, and stainless steel.

6. The outer layer may be made of polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), polyhydroxyaldehyde (PHA), polylactic acid (PLA), thermoplastic starch (TPS), polyvinyl alcohol (PVA), polycaprolactam (PCL), polyethylene (PE), polypropylene (PP), ethylene vinyl acetate (ethylene vinyl acetate), or a combination of these.

2. The film of claim 1, comprising one selected from the group consisting of polyvinyl acetate (EVA), ethylene vinyl alcohol (EVOH), polyvinylidene chloride (PVDC), polyethylene terephthalate (PET), and nylon.

7. The film of claim 1 , wherein the sealant layer comprises a thermal adhesive resin.

8. The method includes a step of storing the cell pouch film according to any one of claims 1 to 7, The storage temperature in the above step is 48-57°C.

9. The storage method according to claim 8, wherein the storage period in the step is 10 to 300 days.

10. The storage method according to claim 8, wherein the relative humidity during storage in said step is 5% to 25%.

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