KR102089415B1 - Sealing film for secondary battary lead tab - Google Patents

Abstract

In the present specification, a sealing film for a secondary battery lead tab, comprising: a core layer comprising a homopropylene resin and an organic filler; And a skin layer comprising a polypropylene-based resin in which dicarboxylic acid or an acid anhydride thereof is graft copolymerized, wherein the skin layer is formed on one or both sides of the core layer, for a secondary battery lead tab. A sealing film is provided.

Description

Sealing film for secondary battery lead tab {SEALING FILM FOR SECONDARY BATTARY LEAD TAB}

The present specification discloses a sealing film for a lead tab that provides heat dissipation performance to a polymer sealing film for a lead tab of a secondary battery for sealing between a lead tab of a secondary battery and an exterior material.

In recent years, various electronic products such as notebooks and mobile phones have progressed at high speed and high performance. With the increase in performance and miniaturization of electronic products, the battery components embedded therein are being increased in capacity and high integration, and as a result, a lot of heat is generated in electronic products. In addition, heat generation problems are gradually emerging due to the enlargement and high performance of pouch type batteries used for EV and ESS. In particular, the heat generated from the battery shortens the life of the product or causes malfunctions or malfunctions, and in severe cases, may cause an explosion or fire.

Accordingly, while maintaining the dimensional stability, which is a physical property required for the lead-tap sealing film, and excellent thermal adhesion to metals and exterior materials, while providing electrical insulation, the heat generated from the battery is effectively dropped to effectively stabilize the battery and the efficiency of the battery. There is a need for a sealing film that can improve the.

In embodiments of the present invention, while maintaining the dimensional stability, excellent thermal adhesion to the metal and the exterior material, while providing electrical insulation while effectively dropping the heat generated by the battery to improve the stability and efficiency of the battery of the secondary battery It is intended to provide a sealing film for a lead tab.

In one embodiment of the present invention, in a sealing film for a secondary battery lead tab, a core layer comprising a homo-propylene resin and an organic filler; And a skin layer comprising a polypropylene-based resin in which dicarboxylic acid or an acid anhydride thereof is graft copolymerized, wherein the skin layer is formed on one or both sides of the core layer, for a secondary battery lead tab. A sealing film is provided.

In an exemplary embodiment, the polypropylene-based resin in which the dicarboxylic acid or an acid anhydride thereof is graft copolymerized is maleic acid, maleic anhydride, fumaric acid, maleimide, maleimide anhydride, itaconic acid, itaconic anhydride, and derivatives thereof. One or more polar groups selected from the group consisting may be introduced.

In an exemplary embodiment, the polypropylene-based resin in which the dicarboxylic acid or an acid anhydride thereof is graft copolymerized may be a maleic anhydride-grafted polypropylene-based resin.

In an exemplary embodiment, the organic filler is modified graphite, and the modified graphite may include one or more selected from the group consisting of silica, magnesium oxide, zinc oxide, aluminum hydroxide, titanium dioxide, and titanium hydroxide.

In an exemplary embodiment, the average particle size of the organic filler may be 500 nm to 5 μm.

In an exemplary embodiment, the organic filler may include 25 to 55% by weight based on the total weight of the core layer composition.

In an exemplary embodiment, the core layer and the skin layer may further include a thermoplastic elastomer and a nucleating agent.

In an exemplary embodiment, the nucleating agent includes at least one selected from the group consisting of a transparent nucleating agent and a rigid nucleating agent, and the transparent nucleating agent is a phosphate ester salt, sodium benzoate, lithium benzoate, aluminum hydroxy dipara-t-butyl benzo Eight (Aluminum hydroxy dipara t-butyl benzoate, Al-PTBBA) and at least one selected from the group consisting of talc, the rigid nucleating agent is a sorbitol-based nucleating agent, nonitol-based nucleating agent and para-t-butylphenol-sodium (PTBP- Na) may include one or more selected from the group consisting of complexes.

In an exemplary embodiment, the nucleating agent includes both a transparent nucleating agent and a rigid nucleating agent, and the rigid nucleating agent and the transparent nucleating agent may be included in a weight ratio of 3: 7 to 7: 3.

In an exemplary embodiment, in the core layer and the skin layer, the nucleating agent may be included in a weight ratio of 2 to 10% by weight, and the thermoplastic elastomer may be included in a weight ratio of 10 to 30% by weight.

In an exemplary embodiment, the core layer has a thickness of 10 to 80 μm,

The skin layer may have a thickness of 25 to 40 μm.

The sealing film for the lead tab of the secondary battery of the present invention has dimensional stability, excellent thermal adhesion with metals and exterior materials, and effectively dissipates the heat generated in the battery, thereby improving the stability of the battery and the efficiency of the battery. Performance.

1 shows a configuration diagram showing a laminated structure of a conventional multilayer lead tab sealing film.
2 is a block diagram showing a stacked structure of a sealing film for a lead tab according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in more detail.

The embodiments of the present invention disclosed in the text are exemplified for illustrative purposes only, and the embodiments of the present invention may 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 variously modified and have various forms, and the embodiments are not intended to limit the present invention to a specific disclosed form, and all modifications, equivalents, or substitutes included in the spirit and scope of the present invention It should be understood to include.

In the present specification, the term "lead tap" refers to a portion exposed to the outside of the outer packaging material among the electrode terminals (tabs) drawn from the electrode group of the secondary battery.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Figure 2 shows an exemplary form of the present invention. Referring to FIG. 2, the sealing film 100 for a secondary battery lead tab according to embodiments of the present invention includes a core layer 10 and a skin layer 20, wherein the skin layer is one of the core layers It may be formed on a side or both sides.

Core layer

In an exemplary embodiment, the core layer 10 may include a homo propylene resin and an organic filler.

First, since the core layer 10 improves physical stability and increases heat resistance as a substrate role, a high melting point and high stiffness can be used. Accordingly, the core layer 10 may include a homo polypropylene resin having a melting point of 160 ° C or higher. More specifically, the core layer 10 may include a non-polar homo polypropylene resin.

In an exemplary embodiment, the homo polypropylene resin in the core layer 10 may be included in a weight ratio of 60 to 80% by weight. When included in less than 60% by weight, physical properties such as heat adhesion workability may be deteriorated, and when exceeded 80% by weight, physical properties such as sealability may be deteriorated.

In an exemplary embodiment, the core layer 10 may further include a thermoplastic elastomer to improve heat resistance.

Specifically, the thermoplastic elastomer is not particularly limited, and examples thereof include an olefin-based thermoplastic elastomer, a styrene-based elastomer, and a hydrogenated styrene-based elastomer.

In an exemplary embodiment, the olefin-based thermoplastic elastomer is not particularly limited, and examples thereof include ethylene-α-olefin copolymers and the like. For example, examples of the α-olefins include propylene, 1-butene, and 1-hexane.

On the other hand, styrene-based elastomers and hydrogenated styrene-based elastomers are not particularly limited, but include, for example, styrene-ethylene butylene-styrene copolymers, styrene-ethylene propylene-styrene copolymers, styrene-ethylene butylene-styrene hydrogenated copolymers, And styrene-ethylene propylene-styrene hydrogenated copolymers.

Among them, it may be preferable to use at least one thermoplastic elastomer selected from the group consisting of ethylene-propylene rubber (EPR) and ethylene-propylene-butene rubber (EPBR) as the thermoplastic elastomer.

On the other hand, the melting point of the thermoplastic elastomer is preferably 80 ℃ or less. By using a thermoplastic elastomer having a melting point of 80 ° C. or less, there is an advantage that sufficient adhesion to the tab surface can be secured during sealing bonding.

In addition, the MFR of the thermoplastic elastomer is preferably 5 g / 10 minutes or less.

In an exemplary embodiment, it is preferred that the gel fraction of the thermoplastic elastomer is 20-90%. When the gel fraction is less than 20%, the degree of crosslinking is insufficient, and the amount of the elastomer melted when heat-sealed becomes too large. If the gel fraction exceeds 90%, the degree of crosslinking is too large and the adhesion may be deteriorated.

On the other hand, the thermoplastic elastomer in the core layer 10 may be included in a weight ratio of 10 to 30% by weight. When included in less than 10% by weight, the sealing film has reduced sealing properties, and if it exceeds 30% by weight, heat resistance may be reduced.

On the other hand, the core layer 10 may further include a nucleating agent to improve heat curability, and the nucleating agent may include one or more selected from the group consisting of a transparent nucleating agent and a rigid nucleating agent.

The sealing film for a conventional secondary battery lead tab contains only a thermoplastic elastomer in a core layer or a skin layer, and in this case, the thermal curing degree of the film is lowered, thereby preventing the moisture or air from external moisture and air permeation / permeability from the electrolyte inside the battery. The barrier properties are significantly reduced (see Fig. 1). The sealing film 100 according to an embodiment of the present invention may further include a nucleating agent in the core layer 10 and the skin layer 20 to compensate for this, and accordingly, the thermal curing degree of the film is improved, thereby improving barrier properties. It can be increased, and heat adhesion, sealing properties, etc. can be improved.

In an exemplary embodiment, the transparent nucleating agent may impart transparency and flexibility, and a phosphate ester salt, sodium benzoate, lithium benzoate, aluminum hydroxy dipara t-butyl benzoate, Al -PTBBA) and one or more selected from the group consisting of talc.

The rigid nucleating agent can accelerate the crystallization rate of the polymer and increase the crystallization rate by miniaturizing the crystal size, and is a group consisting of a sorbitol-based nucleating agent, a nonitol-based nucleating agent, and a para-t-butylphenol-sodium (PTBP-Na) complex. It may include one or more selected from. The sorbitol-based nucleating agent may include one or more selected from the group consisting of benzylidene sorbitol, methylbenzylidene sorbitol, ethylbenzylidene sorbitol, and 3,4-dimethylbenzylidene sorbitol, and the nonitol-based nucleating agent is 1,2,3- Trideoxy-4,6: 5,7-bis-0-[(4-propylphenyl) methylene] -nonitol.

In an exemplary embodiment, it may be desirable for the core layer 10 to include both rigid and transparent nucleating agents. In this case, the rigid nucleating agent and the transparent nucleating agent may be mixed in a weight ratio of 3: 7 to 7: 3. If it is less than 3: 7, moisture permeability may also be deteriorated, and if it is more than 7: 3, heat adhesion workability may be deteriorated.

In one embodiment, the core layer 10 may include a rigid nucleating agent and a transparent nucleating agent in a ratio of 1: 1.

Nucleating agent in the core layer 10 may be included in a weight ratio of 2 to 10% by weight. When included in excess of 10% by weight, heat resistance may be reduced, and when included in less than 2% by weight, adhesiveness may be reduced.

In an exemplary embodiment, the core layer 10 may have a thickness in the range of 10 to 80 μm. For example, the core layer 10 may have a thickness of about 30 μm. When the thickness is less than 10 μm, the stiffness of the sealing film 100 may be deteriorated, and when it exceeds 80 μm, the thickness of the skin layer 20 may be relatively thin, thereby deteriorating the adhesion between the lead tab and the outer packaging material.

In an exemplary embodiment, the core layer 10 may include an organic filler, and the organic filler may be modified graphite. Graphite is a conductive material having a high thermal conductivity, and through modification, it is possible to obtain a non-conductive property having insulating properties while maintaining the properties of the high thermal conductivity possessed by graphite.

Specifically, the modified graphite may include one or more selected from the group consisting of silica, magnesium oxide, zinc oxide, aluminum hydroxide, titanium dioxide, and titanium hydroxide. For example, the modified graphite may be coated with at least one selected from the group consisting of silica, magnesium oxide, zinc oxide, aluminum hydroxide, titanium dioxide, and titanium hydroxide.

For example, the modified graphite may be manufactured by coating silica on the surface of graphite through a sol-gel method by a chemical method, thereby retaining the inherent properties of high thermal conductivity and new to existing graphite of a non-conductive type that does not conduct electricity. It may be a characteristic added.

In an exemplary embodiment, the average particle size of the organic filler may be 500 nm to 5 μm. Preferably, the average particle size of the organic filler may be 500 nm to 3 μm, or 500 nm to 1 μm. By using an organic filler having an average particle size in the above range, it is possible to prevent agglomeration of each other and uneven mixing and smooth mixing of the process.

In general, the particle size of the organic filler added to the core layer 10 is twice the particle size of graphite, so the number of interfaces with the polymer is half, so the larger the particles, the better, but if the particle size is too large, for example, 5 If it is more than µm, film formation (filming) is difficult during the process of extruding the film, or graphite particles are stuck in the T-die part of the extrusion machine, which can damage the equipment.

In an exemplary embodiment, the organic filler may be included in an amount of 25 to 55% by weight based on the total weight of the core layer composition. Specifically, the organic filler may include 25-40% by weight, 30-50% by weight, 30-45% by weight, or 30-40% by weight relative to the total weight of the core layer composition. Preferably, the organic filler may be included 35 to 45% by weight relative to the total weight of the core layer composition. For example, the organic filler may be included in about 40% by weight based on the total weight of the core layer composition. When the organic filler exceeds 55% by weight based on the total weight of the core layer composition, filming may be difficult, and when the organic filler is less than 25% by weight relative to the total weight of the core layer composition, heat dissipation performance may be poor.

In general, it is determined whether or not filming is possible depending on the amount of modified graphite to be filled, and as the amount increases, the heat dissipation performance is excellent, whereas filming is difficult, so an appropriate amount of addition considering heat dissipation performance and filming is required.

Skin layer

Meanwhile, the skin layer 20 may be formed on one surface or both surfaces of the core layer, and specifically, may be formed between a lead tab including a metal and the core layer 10, or a metal It is formed between the exterior material and the core layer 10, including, it is possible to improve their adhesion.

In an exemplary embodiment, the skin layer 20 may include a polypropylene-based resin in which dicarboxylic acids or acid anhydrides thereof are graft copolymerized.

In an exemplary embodiment, the skin layer 20 may include a polypropylene-based resin graft copolymerized with a lead tab containing a metal and a dicarboxylic acid or an acid anhydride thereof, and a nucleating agent and a thermoplastic elastomer. It may further include.

The skin layer 20 may be well sealed between a lead tab containing a metal and the core layer 10, or may be well sealed between an exterior material containing a metal and the core layer 10. A polypropylene-based resin in which a dicarboxylic acid having an melting point of 120 to 150 ° C. or an acid anhydride thereof is graft copolymerized may be used.

In one embodiment, the polypropylene-based resin in which the dicarboxylic acid or an acid anhydride thereof is graft copolymerized may be a maleic anhydride-grafted polypropylene resin.

Specifically, the polypropylene-based resin in which the dicarboxylic acid or an acid anhydride thereof is graft copolymerized may be a maleic anhydride graft-random polypropylene resin.

In an exemplary embodiment, the polypropylene-based resin in which the dicarboxylic acid or an acid anhydride thereof is graft copolymerized in the skin layer 20 may be included in a weight ratio of 60 to 80% by weight. When included in less than 60% by weight, the adhesion rate decreases, and when it exceeds 80% by weight, the heat resistance decreases.

The skin layer 20 may further include a thermoplastic elastomer in order to impart a sealing effect to the polypropylene-based resin.

The thermoplastic elastomer is not particularly limited, and examples thereof include olefin-based thermoplastic elastomers, styrene-based elastomers, hydrogenated styrene-based elastomers, and the like, and may be substantially the same or similar to the thermoplastic elastomer of the core layer described above.

In one embodiment, the thermoplastic elastomer contained in the skin layer 20 and the thermoplastic elastomer contained in the core layer 10 may be the same.

On the other hand, the thermoplastic elastomer in the skin layer 20 may be included in a weight ratio of 10 to 30% by weight. When included in less than 10% by weight, the sealing property of the sealing film 100 decreases, and when it exceeds 30% by weight, heat resistance may decrease.

In an exemplary embodiment, skin layer 20 may have a thickness in the range of 25-40 μm. If it has a thickness of 40 μm or more, the stiffness of the sealing film 100 may be lowered, and if it is less than 25 μm, the adhesive strength between the lead tab and the outer packaging material may be reduced.

On the other hand, the skin layer 20 may further include a nucleating agent to improve the heat curability, the nucleating agent may include at least one selected from the group consisting of a transparent nucleating agent and a rigid nucleating agent.

In one embodiment, the nucleating agent included in the skin layer 20 may be the same as that included in the core layer 10.

In an exemplary embodiment, the transparent nucleating agent imparts transparency and flexibility, phosphate ester salt, sodium benzoate, lithium benzoate, aluminum hydroxy dipara t-butyl benzoate, Al -PTBBA) and one or more selected from the group consisting of talc.

The rigid nucleating agent promotes the crystallization rate of the polymer, refines the crystal size to increase the crystallization rate, and is selected from the group consisting of sorbitol-based nucleating agent, nonitol-based nucleating agent, and para-t-butylphenol-sodium (PTBP-Na) complex. It may include the above. The sorbitol-based nucleating agent may include one or more selected from the group consisting of benzylidene sorbitol, methylbenzylidene sorbitol, ethylbenzylidene sorbitol, and 3,4-dimethylbenzylidene sorbitol, and the nonitol-based nucleating agent is 1,2,3- Trideoxy-4,6: 5,7-bis-0-[(4-propylphenyl) methylene] -nonitol.

The skin layer 20 may include both a rigid nucleating agent and a transparent nucleating agent. In this case, the rigid nucleating agent and the transparent nucleating agent may be mixed in a weight ratio of 3: 7 to 7: 3. When it is less than 3: 7, physical properties such as moisture permeability may be deteriorated, and when it exceeds 7: 3, physical properties such as heat adhesion workability may be deteriorated.

In one embodiment, the skin layer 20 may include a rigid nucleating agent and a transparent nucleating agent in a ratio of 1: 1.

In the skin layer 20, the nucleating agent may be included in a weight ratio of 2 to 10% by weight. When included in excess of 10% by weight, heat resistance may be reduced, and when included in less than 2% by weight, adhesiveness may be reduced.

In an exemplary embodiment, skin layer 20 may have a thickness in the range of 25-40 μm. If it has a thickness of 40 μm or more, the stiffness of the sealing film 100 may be lowered, and if it is less than 25 μm, the adhesive strength between the lead tab and the outer packaging material may be reduced.

In an exemplary embodiment, the sealing film 100 for a secondary battery lead tab may have a thickness of 80 to 120 um.

As described above, the sealing film 100 for a secondary battery lead tab according to one embodiment of the present invention effectively maintains dimensional stability, excellent thermal adhesion with metals and exterior materials, and provides electrical insulation while effectively providing heat generated by the battery. Dropping can improve battery stability and battery efficiency.

On the other hand, in another embodiment of the present invention, a method of manufacturing a sealing film for a secondary battery lead tab includes: a core layer 10 including homopropylene, a thermoplastic elastomer and a nucleating agent; A first skin layer 21 comprising a polypropylene-based resin, a nucleating agent and a thermoplastic elastomer in which a dicarboxylic acid or an acid anhydride thereof is graft copolymerized; And a second skin layer 22 comprising a polypropylene-based resin in which a dicarboxylic acid or an acid anhydride thereof is graft copolymerized, a thermoplastic elastomer, and a nucleating agent; A method of manufacturing a sealing film for a secondary battery lead tab including a first skin layer 21, a core layer 10, and a second skin layer 22 sequentially stacked by coextrusion is provided.

Hereinafter, the present invention will be described in more detail through examples. These examples are only for illustrating the present invention, it will be apparent to those skilled in the art that the scope of the present invention is not to be construed as limited by these examples.

Example

[Example 1] Preparation of sealing film

A sealing film for a lead tab having a three-layer structure of a first skin layer / core layer / second layer was manufactured using a coextruder. At this time, the total thickness of the film was 100 μm. At this time, the first skin layer was prepared to contain a maleic anhydride graft polypropylene resin, a nucleating agent and an elastomer (manufactured by EPDM ELASTOMER, Samjin Polymer) in a weight ratio of 65: 5: 30 (thickness: 35 μm). The core layer was prepared to contain a silica-modified graphite having a diameter of 500 nm, a homo polypropylene resin, a nucleating agent, and an elastomer in a weight ratio of 20: 45: 5: 30 (thickness: 30 μm). The second skin layer was prepared to contain the maleic anhydride graft polypropylene resin, a nucleating agent, and an elastomer in a weight ratio of 65: 5: 30 (thickness: 35 μm). As a nucleating agent, a 1: 1 mixture of a rigid nucleating agent and a transparent nucleating agent was used, and as a rigid nucleating agent, a sorbitol-based nucleating agent product (manufactured by Adeka NA-27) was used, and a transparent nucleating agent was a phosphate ester salt product (made by Adeka NA-21) ) Was used. At this time, the thickness of the entire sealing film is 100 um.

[ Comparative example  One]

A sealing film was prepared in the same manner as in Example 1, except that the core layer did not contain silica-modified graphite.

[Experimental Example 1] Insulation properties analysis experiment

First, an aluminum (Al) electrode plate most used as a lead tab of a lithium secondary battery was prepared. And the sealing film according to each Example and Comparative Example was cut to a width of 10 mm and a length of 12 cm, followed by primary bonding by applying heat of 160 ° C. and pressure of 30 kgf for 3 seconds. Subsequently, heat was adhered to the Al electrode plate by pressing the film at a pressure of 30 kgf for 3 seconds while heating at 200 ° C. The heat-bonding strength was measured for each of the heat-bonded specimens.

The thermal adhesive strength was measured by applying an increasing load at a speed of 140 mm / min using an adhesive strength meter (AGS-1kNX model from SHIMADZU, Japan) to measure the thermal adhesive strength between the Al electrode plate and the sealing film (Japan, AGS from SHIMADZU). -1kNX model). Other comparative experiments confirmed the heat dissipation performance, heat diffusivity, and insulating properties of the lead tab film. The heat dissipation performance was confirmed by attaching each lead-tap film to a heat source based on a 60 ° C heat source and conducting experiments of temperature change over time to confirm the lowered temperature. The heat diffusivity was confirmed by using a thermal imaging camera (model VT-04 from Fluke, USA) after 1 hour of attaching each lead tab film to the heat source based on the 60 ° C. heat source. Insulation was checked by using an insulation resistance meter (multimeter) (Model IR4051-10 from Hioki, Japan). The results are shown in Table 1 below. Here, excellent (◎), good (○), and normal (△) are unsatisfactory (X), respectively.

Comparative Example 1 Example 1 Heat dissipation performance 60 ℃ 55 ℃ Thermal diffusivity X ◎ Thermal adhesive strength (N / 15mm) 29 29 Insulation ◎ ◎

[ Example  1-2 and Comparative example  2-4] Organic filler  Production of sealing films of different sizes

A sealing film was prepared by changing only the size of the organic filler in the same production method as the sealing film of Example 1. Specifically, the diameters of the organic fillers were 500 nm (Example 1), 1 μm (Example 2), 3 μm (Comparative Example 2), 5 μm (Comparative Example 3), and 7 μm (Comparative Example 4), respectively. It was prepared as.

[Experimental Example 2] Filming analysis according to the size change of the organic filler

In order to check whether or not filming is possible during the film extrusion process according to the particle size of the organic filler, after preparing the particle size of the organic filler differently (Example 1-2 and Comparative Example 2-4), other resins and additives The film was extruded through blending with the field. A 3-layer film was extruded, and a film having a thickness of 100 um, which is most commonly used among lead tab film thicknesses, was produced. During the extrusion process, silica-modified graphite was added to the core layer to extrude the film, and the thickness of the core layer in the 3-layer was 30 μm. Whether or not filming was possible during the extrusion process according to the silica-modified graphite particle size was visually observed and the results are shown in Table 2 below. Here, excellent (◎), good (○), and normal (△) are unsatisfactory (X), respectively.

Example 1
(500 nanometers) Example 2
(1 micro) Comparative Example 2
(3 micro) Comparative Example 3
(5 micro) Comparative Example 4
(7 micro) Film ◎ ◎ ○ △ X

[ Example  3-5 and Comparative example  5-6] Organic filler  Production of sealing films with different contents

A sealing film was prepared by changing only the content of the organic filler in the same production method as the sealing film of Example 1. Specifically, the content of the organic filler relative to the total weight of the core layer 20% by weight (Example 3), 30% by weight (Example 4), 40% by weight (Example 5), 50% by weight (Comparative Example 5) , And 60% by weight (Comparative Example 6).

[Experimental Example 3] Analysis of filming and heat dissipation performance according to the content of organic filler

In the film extrusion process according to the amount of modified graphite added, the films were extruded with different amounts of modified graphite added to confirm whether filming is possible and heat dissipation performance. A 3-layer film was extruded, and a film having a thickness of 100 um, which is most commonly used among lead tab film thicknesses, was produced. During the extrusion process, the amount of modified graphite added to the core layer was added differently to extrude the film, and the thickness of the core layer was 30 μm. In the extrusion process according to the amount of modified graphite added, whether filming was possible or not and heat dissipation performance according to the amount of addition were observed, and the results are shown in [Table 3]. Here, excellent (◎), good (○), and normal (△) are unsatisfactory (X), respectively.

Example 3
(20% by weight) Example 4
(30%) Example 5
(40%) Comparative Example 5
(50%) Comparative Example 6
(60%) Film ◎ ◎ ◎ ○ X Heat dissipation performance 60 ℃ 57 ℃ 55 ℃ 53 ℃ 51 ℃

The embodiments of the present invention described above should not be construed as limiting the technical spirit of the present invention. The scope of protection of the present invention is limited only by the matters described in the claims, and a person having ordinary knowledge in the technical field of the present invention can improve and modify the technical spirit of the present invention in various forms. Accordingly, such improvements and modifications will fall within the protection scope of the present invention as long as it is apparent to those skilled in the art.

Claims (11)

In the sealing film for a secondary battery lead tab,
A core layer comprising a homopropylene resin, an organic filler, a thermoplastic elastomer, and a nucleating agent; And
Contains a skin layer comprising a polypropylene-based resin, a thermoplastic elastomer, and a nucleating agent in which the dicarboxylic acid or acid anhydride thereof is graft copolymerized;
The skin layer is formed on one or both sides of the core layer,
The nucleating agent includes a rigid nucleating agent, a sealing film for a secondary battery lead tab. According to claim 1,
The dicarboxylic acid or an acid anhydride thereof graft copolymerized polypropylene-based resin is one selected from the group consisting of maleic acid, maleic anhydride, fumaric acid, maleimide, maleimide anhydride, itaconic acid, itaconic anhydride and derivatives thereof The sealing film for secondary battery lead tabs in which the above polar groups are introduced. According to claim 1,
The polypropylene-based resin in which the dicarboxylic acid or an acid anhydride thereof is graft copolymerized is a maleic anhydride-grafted polypropylene-based resin, a sealing film for secondary battery lead tabs. According to claim 1,
The organic filler is a modified graphite, and the modified graphite includes at least one selected from the group consisting of silica, magnesium oxide, zinc oxide, aluminum hydroxide, titanium dioxide, and titanium hydroxide. According to claim 1,
The average particle size of the organic filler is 500 nm to 5 μm, a sealing film for a secondary battery lead tab. According to claim 1,
The organic filler is 25 to 55% by weight based on the total weight of the core layer composition, a sealing film for a secondary battery lead tab. delete In the sealing film for a secondary battery lead tab,
A core layer comprising a homopropylene resin, an organic filler, a thermoplastic elastomer, and a nucleating agent; And
Contains a skin layer comprising a polypropylene-based resin, a thermoplastic elastomer, and a nucleating agent in which the dicarboxylic acid or acid anhydride thereof is graft copolymerized;
The skin layer is formed on one or both sides of the core layer,
The nucleating agent includes at least one selected from the group consisting of a transparent nucleating agent and a rigid nucleating agent,
The transparent nucleating agent includes at least one selected from the group consisting of phosphate ester salt, sodium benzoate, lithium benzoate, aluminum hydroxy dipara t-butyl benzoate (Al-PTBBA) and talc. and,
The rigid nucleating agent includes one or more selected from the group consisting of a sorbitol-based nucleating agent, a nonitol-based nucleating agent and a para-t-butylphenol-sodium (PTBP-Na) complex, sealing film for a secondary battery lead tab. In the sealing film for a secondary battery lead tab,
A core layer comprising a homopropylene resin, an organic filler, a thermoplastic elastomer, and a nucleating agent; And
Contains a skin layer comprising a polypropylene-based resin, a thermoplastic elastomer, and a nucleating agent in which the dicarboxylic acid or acid anhydride thereof is graft copolymerized;
The skin layer is formed on one or both sides of the core layer,
The nucleating agent includes both a transparent nucleating agent and a rigid nucleating agent,
The rigid nucleating agent and the transparent nucleating agent are contained in a weight ratio of 3: 7 to 7: 3, a sealing film for a secondary battery lead tab. The method according to any one of claims 1, 8, and 9,
In the core layer and the skin layer, the nucleating agent is included in a weight ratio of 2 to 10% by weight, and the thermoplastic elastomer is included in a weight ratio of 10 to 30% by weight. According to claim 1,
The core layer has a thickness of 10 to 80μm,
The skin layer has a thickness of 25 to 40 μm, a sealing film for a secondary battery lead tab.

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