KR20180092819A - Lead sealant films and secondary batteries using the same - Google Patents

Abstract

The present invention relates to a lead sealant film having a high adhesive property for sealing a gap between an electrode lead and a case and strongly resistant to modification and to a secondary battery using the same. According to the present invention, the lead sealant film comprises: a first layer including an acid-modified copolymer, an ethylene-based elastomer, and a low-density polyolefin; a second layer bonded onto the first layer and including an acid-modified copolymer, an ethylene-based elastomer, a low-density polyolefin, a cross-linking agent, and a phenol-based antioxidant; and a third layer bonded onto the second layer and including an acid-modified copolymer, an ethylene-based elastomer, and a vinyl-based copolymer, wherein the cross-linking agent includes at least one selected from the group consisting of trimethylolpropane methacrylate, pentaerythritol triacrylate, etching recall dimethacrylate, triallyl cyanurate, and triaryl isocyanurate. The phenol-based antioxidant includes 0.1 to 0.4 parts by weight based on 100 parts by weight of a compound included in the second layer.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead sealant film,

The present invention relates to a rechargeable battery, and more particularly, to a reed sealant film having high adhesiveness for sealing between an electrode lead and a case and resistant to denaturation, and a secondary battery using the same.

2. Description of the Related Art In recent years, portable electronic devices such as a camera-integrated video tape recorder (VTR), a cellular phone, and a portable computer, which have been reduced in size and weight, have appeared. As a portable power source for these electronic devices, research and development have been actively made on batteries, particularly secondary batteries, and non-aqueous electrolyte secondary batteries (so-called lithium ion batteries) among them.

Typically, in view of the shape of the battery, there is a high demand for a prismatic secondary battery and a pouch-type secondary battery that can be applied to products such as mobile phones with a small thickness. In terms of materials, lithium ion batteries having high energy density, discharge voltage, There is a high demand for a lithium secondary battery such as a lithium ion polymer battery.

In order to take advantage of the thin and light weight of a lithium secondary battery, various types of batteries are known in which a battery element is sealed by using a so-called laminate film in which a plastic film or a plastic film is bonded to a metal.

The pouch type lithium secondary battery includes an electrode assembly, electrode tabs extending from the electrode assembly, and a case accommodating the electrode leads and the electrode assembly welded to the electrode tabs.

Here, the electrode leads and the case are integrated by thermal fusion between the films. In this case, when a relatively high heat or pressure is applied during the heat fusion process, the film is damaged and the electrode lead is exposed.

As a result, the case and the electrode lead are brought into contact with each other to cause a short circuit, resulting in a significant decrease in safety and a shortened battery life.

In addition, the pouch type lithium secondary battery may have a problem that the adhesion between the film and the case or between the film and the electrode lead is reduced due to subsequent charging and discharging operations and external forces such as vibration and drop, and leakage of the internal electrolyte may occur.

Japanese Unexamined Patent Application Publication No. 2006-0128096 discloses a lead wire for a nonaqueous electrolyte battery in which a positive electrode, a negative electrode and a separator are housed in a battery case in the form of a laminated film. The surface of the electrode lead wire, which is thermally fused to the battery case, Forming a composite coating layer by applying a treatment liquid containing a resin component and a metal salt to the battery case and forming an insulator that is thermally fused to the battery case on the outer side of the composite coating layer, Aqueous electrolyte battery which is capable of preventing moisture penetration of the non-aqueous electrolyte and improving the adhesion.

The lead wire for a nonaqueous electrolyte battery has a complicated process of manufacturing an electrode lead because a process of applying the resin lead to the surface of the electrode lead by adjusting the compounding ratio of the resin component and the metal salt component is added.

Japanese Unexamined Patent Application Publication No. 2007-0005101 discloses a lead wire for a nonaqueous electrolyte battery in which an insulator is formed on the surface of a conductor. The insulator includes an adhesive layer adhered to the conductor, and a cross- A plurality of grooves or holes filled with the same material as the adhesive layer are formed in the crosslinked resin layer so as to improve the electrical insulation and sealing property of the heat fusion portion located around the electrode lead, .

However, the disclosed lead wire for a non-aqueous electrolyte battery has a problem in that a complicated manufacturing process of forming a plurality of grooves or holes in the crosslinked resin layer formed on the adhesive layer and filling the same material as the adhesive layer has to be added.

It is therefore an object of the present invention to provide a lead sealant film which is highly resistant to degeneration and has high adhesiveness for sealing between an electrode lead and a case in a simple manufacturing process, and a secondary battery using the lead sealant film.

The lead sealant film according to the present invention comprises a first layer comprising an acid-modified copolymer, an ethylenic elastomer and a low-density polyolefin, a first layer laminated on the first layer and comprising an acid-modified copolymer, an ethylenic elastomer, a low-density polyolefin, Based antioxidant and a third layer bonded on the second layer and comprising an acid-modified copolymer, an ethylenic elastomer, and a vinyl-based copolymer, wherein the cross-linking agent is trimethylolpropane Wherein said antioxidant is at least one selected from the group consisting of triallyl cyanurate, triallyl cyanurate, triallyl cyanurate, triallyl cyanurate, And 0.1 to 0.4 parts by weight based on 100 parts by weight of the compound contained.

In the lead sealant film according to the present invention, the acid-modified copolymer is preferably at least one of maleic anhydride modified polypropylene, maleic anhydride modified polyethylene, carboxylic acid modified polypropylene, carboxylic acid modified polyethylene, acrylic modified polypropylene and acrylic modified polyethylene Or the like.

In the lead sealant film according to the present invention, the ethylene elastomer includes at least one of ethylene propylene rubber (EPDM) and ethylene propylene copolymer (EPR).

The lead sealant film according to the present invention is characterized in that the low density polyolefin includes at least one of low density polyethylene (LDPE) and linear low density polyethylene (LLDPE).

In the lead sealant film according to the present invention, the ratio of the acid-modified copolymer to the total weight part of the first layer is 20% or more.

A secondary battery according to the present invention includes an electrode assembly including a plurality of electrode tabs, a plurality of electrode leads connected to the plurality of electrode tabs and exposed to the outside, a lead sealant film attached to at least one side of each of the plurality of electrode leads, And a case for accommodating the electrode assembly in a state that a part of the plurality of electrode leads is exposed to the outside, wherein the lead sealant film is bonded between the electrode lead and the case, and the acid-modified copolymer, And a low-density polyolefin; a second layer bonded on the first layer and comprising an acid-modified copolymer, an ethylenic elastomer, a low-density polyolefin, a crosslinking agent and a phenol-based antioxidant; And a third layer comprising an acid-modified copolymer, an ethylenic elastomer, and a vinyl-based copolymer, wherein the cross- Wherein the antioxidant is at least one selected from the group consisting of platinum methacrylate, pentaerythritol triacrylate, etchrecoll dimethacrylate, triallyl cyanurate and triallyl isocyanurate, And 0.1 to 0.4 parts by weight based on 100 parts by weight of the compound contained in the layer.

The lead sealant film according to the present invention can control the melting point of each layer through the acid-modified copolymer contained in the first layer, the second layer and the third layer, A lead sealant film can be provided.

Further, in the lead sealant film according to the present invention, by adding a crosslinking agent to the second layer, only the second layer can be selectively crosslinked, and the adhesion between the first layer and the third layer can be increased.

In addition, the lead sealant film according to the present invention may contain 0.1 to 0.4 parts by weight of the phenolic antioxidant in 100 parts by weight of the second compound in the second layer, thereby ensuring strong tensile properties while preventing oxidation of the lead sealant film .

1 is a view showing a secondary battery according to the present invention.
FIG. 2 is a view showing an assembled state of an electrode lead, a lead sealant film, and a case in a state where the secondary battery of FIG. 1 is assembled.
3 is a view showing a lead sealant film according to the present invention.
4 is a flowchart showing a method of manufacturing a lead sealant film according to the present invention.

In the following description, only parts necessary for understanding the embodiments of the present invention will be described, and the description of other parts will be omitted so as not to obscure the gist of the present invention.

The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary meanings and the inventor is not limited to the meaning of the terms in order to describe his invention in the best way. It should be interpreted as meaning and concept consistent with the technical idea of the present invention. Therefore, the embodiments described in the present specification and the configurations shown in the drawings are merely preferred embodiments of the present invention, and are not intended to represent all of the technical ideas of the present invention, so that various equivalents And variations are possible.

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

FIG. 1 is a view showing a secondary battery according to the present invention, FIG. 2 is a view showing an assembled state of an electrode lead, a lead sealant film and a case in a state where the secondary battery of FIG. 1 is assembled, Fig. 3 is a view showing a lead sealant film. Fig.

Referring to FIGS. 1 to 3, a secondary battery 10 according to the present invention includes an electrode assembly 30, a lead sealant film 80, and a case 20.

Although not shown, the electrode assembly 30 is formed by stacking a stacked, long sheet-like positive electrode and a negative electrode in which an anode and a cathode are sequentially stacked with a separator interposed therebetween in a state in which a separator is interposed therebetween, And then it is compressed in one direction to be a jelly-roll type power generation device which is manufactured in a plate-like structure in cross section.

The electrode assembly 30 may include a plurality of electrode tabs 40 and 50. The plurality of electrode tabs 40 and 50 may include a positive electrode tab 40 protruding from a current collector of the positive electrode and a negative electrode tab 50 protruding from the current collector of the negative electrode. When a plurality of positive electrode current collectors and negative electrode current collectors are provided, the plurality of positive electrode tabs 40 and the plurality of negative electrode tabs 50 may be integrally joined by welding.

The electrode assembly 30 may include a plurality of electrode leads 60 and 70 electrically connected to the plurality of electrode tabs 40 and 50. The plurality of electrode leads 60 and 70 may include a positive electrode lead 60 electrically connected to the positive electrode tab 40 and a negative electrode lead 70 electrically connected to the negative electrode tab 50 . The positive electrode lead 60 and the negative electrode lead 70 may be electrically connected to the positive electrode tab 40 and the negative electrode tab 50, respectively, by welding.

The electrode assembly 30 may be embedded in the case 20 with a portion of the plurality of electrode leads 60 and 70 exposed to the outside.

The lead sealant film 80 may be attached to at least one side of each of the plurality of electrode leads 60 and 70 of the electrode assembly 30. [ The lead sealant film 80 is provided between the plurality of electrode leads 60 and 70 and the case 20 so as to increase the degree of sealing of the case 20. The lead sealant film 80 has a plurality of electrode leads 60 and 70, It is possible to secure an electrically insulated state between them. Here, when the lead sealant film 80 is attached to both side surfaces of the plurality of electrode leads 60 and 70, the lead sealant films 80 may have the same length and may be overlapped with each other with a plurality of electrode leads 60 and 70 therebetween have.

The lead sealant film 80 may include a first layer 81, a second layer 82, and a third layer 83.

Here, the first layer 81 may include a first compound including an acid-modified copolymer, an ethylenic elastomer, and a low density olelefin as a layer in contact with the plurality of electrode leads 60 and 70. Wherein the first compound may further comprise an antioxidant.

The acid-modified copolymer may include at least one of maleic anhydride modified polypropylene, maleic anhydride modified polyethylene, carboxylic acid modified polypropylene, carboxylic acid modified polyethylene, acrylic modified polypropylene, and acrylic modified polyethylene.

For example, as the acid-modified polypropylene resin, a random type polypropylene in which an unsaturated carboxylic acid is grafted or a block type polypropylene can be used. As the polypropylene, homo type polypropylene, random type polypropylene or block type polypropylene can be used. That is, the acid-modified polypropylene resin combines adhesiveness to a plurality of electrode leads 60, 70 and good heat fusion with a casing, and it can be modified with maleic anhydride to have a molecular weight of 10,000 or more.

The ethylenic elastomer may include at least one of ethylene propylene rubber (EPDM) and ethylene propylene copolymer (EPR).

The low density olefins may include at least one of low density polyethylene (LDPE) and linear low density polyethylene (LLDPE).

On the other hand, in the first layer 81, the proportion of the acid-modified copolymer in the first compound may be 20% or more. That is, by giving the first layer 81 a polarity through the acid-modified copolymer, adhesion with the plurality of electrode leads 60 and 70 can be ensured. If the ratio of the acid-modified copolymer is less than 20%, the adhesive strength to the plurality of electrode leads 60 and 70 may be lowered.

The content of the polypropylene or polyethylene in the first layer 81 may be 10 parts by weight or more based on 100 parts by weight of the acid-modified copolymer. In this case, the melting point of the first layer 81 may be between 130 and 150 ° C. That is, the first layer 81 can be set to have a melting point of 130 to 150 ° C by controlling the content of polypropylene or polyethylene in the acid-modified copolymer. If the melting point of the first layer 81 is less than 130 캜, there is a problem that reliability can not be secured when the user of the secondary battery is exposed to a high temperature environment. If the melting point of the first layer 81 exceeds 150 캜, the difference in melting point with the second layer 82 becomes small, resulting in short-circuiting of the air pressure.

The second layer 82 is provided between the first layer 81 and the third layer 83 and may include a second compound including an acid-modified copolymer, an ethylenic elastomer, and a low density olelefin. Here, the second layer 82 may further include a crosslinking agent and an antioxidant.

The acid-modified copolymer may include at least one of maleic anhydride modified polypropylene, maleic anhydride modified polyethylene, carboxylic acid modified polypropylene, carboxylic acid modified polyethylene, acrylic modified polypropylene, and acrylic modified polyethylene.

For example, as the acid-modified polypropylene resin, a random type polypropylene in which an unsaturated carboxylic acid is grafted or a block type polypropylene can be used. As the polypropylene, homo type polypropylene, random type polypropylene or block type polypropylene can be used. That is, the acid-modified polypropylene resin combines adhesiveness to a plurality of electrode leads 60, 70 and good heat fusion with a casing, and it can be modified with maleic anhydride to have a molecular weight of 10,000 or more.

The ethylenic elastomer may include at least one of ethylene propylene rubber (EPDM) and ethylene propylene copolymer (EPR).

The low density olefins may include at least one of low density polyethylene (LDPE) and linear low density polyethylene (LLDPE).

The cross-linking agent may be at least one selected from the group consisting of trimethylolpropane methacrylate, pentaerythritol triacrylate, etchrecoll dimethacrylate, triallyl cyanurate, and triarylisocyanurate. The second layer 82 includes a crosslinking agent so that the first layer 81, the second layer 82 and the third layer 83 are co-extruded and then irradiated with an electron beam to form the second layer 82 By selectively crosslinking, adhesion between the first layer 81, the second layer 82, and the third layer 83 can be enhanced.

The antioxidant may include a phenolic antioxidant and may include 0.1 to 0.4 parts by weight based on 100 parts by weight of the second compound contained in the second layer 82. If the amount of the antioxidant exceeds 0.4 part by weight, the adhesive strength may be lowered.

The second layer 82 may further include an inorganic filler. For example, the inorganic filler may include Clay, Silica, Calcium Carbonate (CaCO ₃ ), Titanium Dioxide (TiO ₂ ), Glass Fiber, and the like. The inorganic filler has no affinity with an olefin polymer having a low surface energy due to its high surface energy. However, due to the content of the acid-modified copolymer, the polarity difference between the first layer 81 and the second layer 82 The inorganic filler can be positioned at the interface of the polymer by the transfer of the inorganic filler to the polymer.

The content of the polypropylene or polyethylene in the second layer 82 may be 20 parts by weight or more based on 100 parts by weight of the acid-modified copolymer. In this case, the melting point of the second layer 82 may be 150 to 170 ° C. If the melting point of the second layer 82 is less than 150 ° C, there is a possibility that the pneumatic pressure short-circuiting may occur due to a small difference in melting point from the first layer 81 or the third layer 83, It is difficult to control.

The third layer 83 is bonded to the second layer 82 and substantially abuts the case 20. The third layer 83 may include a third compound including an acid-modified copolymer, an ethylenic elastomer, and a vinyl-based copolymer. The second layer 82 may further include an antioxidant.

The acid-modified copolymer may include at least one of maleic anhydride modified polypropylene, maleic anhydride modified polyethylene, carboxylic acid modified polypropylene, carboxylic acid modified polyethylene, acrylic modified polypropylene, and acrylic modified polyethylene.

For example, as the acid-modified polypropylene resin, a random type polypropylene in which an unsaturated carboxylic acid is grafted or a block type polypropylene can be used. As the polypropylene, homo type polypropylene, random type polypropylene or block type polypropylene can be used. That is, the acid-modified polypropylene resin combines adhesiveness to a plurality of electrode leads 60, 70 and good heat fusion with a casing, and it can be modified with maleic anhydride to have a molecular weight of 10,000 or more.

The ethylenic elastomer may include at least one of ethylene propylene rubber (EPDM) and ethylene propylene copolymer (EPR).

The vinyl-based copolymer may include ethylene vinyl acetate or ethylene vinyl chloride.

The content of the polypropylene or polyethylene in the third layer 83 may be 10 parts by weight or more based on 100 parts by weight of the acid-modified copolymer. In this case, the melting point of the first layer 83 may be between 130 and 150 ° C. That is, the third layer 83 can be set to have a melting point of 130 to 150 ° C by controlling the content of polypropylene or polyethylene in the acid-modified copolymer. If the melting point of the third layer 83 is less than 130 캜, there is a problem that reliability can not be secured when the user of the secondary battery is exposed to a high temperature environment. If the melting point of the third layer 83 exceeds 150 캜, the difference in melting point with the second layer 82 becomes small, resulting in short-circuiting of the air pressure.

That is, when the melting points of the first layer, the second layer and the third layer are denoted by M1, M2 and M3, M2> M1> M3 can be satisfied. Here, the difference between M1 and M3 can be 10 to 20 占 폚.

The case 20 can receive the electrode assembly 30 in a state where a part of the plurality of electrode leads 60 and 70 is exposed. The case 20 may include a case body 21 having a space for accommodating the electrode assembly 30 and a case cover 22 coupled to the case body 21 to seal the electrode assembly 30 have. The case body 21 and the case cover 22 may include an outer coating layer 20a and a barrier layer 20b and an inner sealant layer 20c, respectively. For example, the outer coating layer 20a may include a stretched nylon film (ONy). For example, the barrier layer 20b may comprise aluminum. For example, the inner sealant layer 20c may comprise a lead-free polypropylene film (CPP). In addition, a hot melt layer (not shown) is coated on the rim of the inner sealant layer 20c, so that the case body 21 and the case cover 22 can be tightly fixed to each other by heat and pressure.

Hereinafter, a method of manufacturing a lead sealant film according to the present invention will be described.

4 is a flowchart showing a method of manufacturing a lead sealant film according to the present invention.

Referring to FIG. 4, a first compound, a second compound, and a third compound are prepared in step S10. Here, the first compound may include an acid-modified copolymer, an ethylenic elastomer, and a low-density polyolefin. The second compound may include an acid-modified copolymer, an ethylenic elastomer, and a low-density polyolefin. The third compound may include an acid-modified copolymer, an ethylenic elastomer, and a vinyl-based copolymer. Examples of the acid-denatured copolymer, the ethylene-based elastomer, the low-density polyolefin and the vinyl-based copolymer have been described above and will be omitted. Here, the first compound, the second compound and the third compound may be formed in a master batch form.

In step S10, a crosslinking agent may be added to the second compound. By adding a crosslinking agent to the second compound, the second layer containing the second compound can be selectively crosslinked through electron beam irradiation in a step S30 to be described later.

In addition, an antioxidant may be added to the first compound, the second compound and the third compound in the step S10, preferably a crosslinking agent is added to the second compound, and an antioxidant is added to the first and third compounds .

In step S10, an inorganic filler may be added to the second compound. Herein, the inorganic filler has a high surface energy and is not compatible with an olefinic polymer having a low polarity. However, the content of the acid-modified copolymer includes a first compound having a high polarity as compared to a second layer containing a second compound Due to the polarity difference between the first layer and the inorganic filler, the inorganic filler can be positioned at the interface between the polymer and the inorganic filler, thereby enhancing the adhesion.

Next, in step S20, a first layer comprising the first compound, a second layer comprising the second compound, and a third compound are co-extruded from the masterbatch in the form of a first compound, a second compound and a third compound A lead sealant film including the third layer can be produced. Here, the content of polyethylene or polypropylene contained in the acid-modified copolymer of the first layer, the second layer and the third layer is different from that of the first layer, the second layer and the third layer, It is possible to produce a lead sealant film having a laminate structure through coextrusion. Accordingly, the manufacturing method of the lead sealant film according to the present invention can reduce the manufacturing cost.

For example, when the melting points of the first layer, the second layer and the third layer are denoted by M1, M2 and M3, M2> M1> M3 can be satisfied. Here, the difference between M1 and M3 can be 10 to 20 占 폚. The melting point M2 of the second layer 82 may be 150 to 170 占 폚, and the melting points M1 and M3 of the first layer and the third layer may be 130 to 150 占 폚.

Next, in step S30, the lead sealant film may be irradiated with an electron beam to selectively crosslink the second layer. That is, the adhesive force can be doubled between the first layer, the second layer and the third layer by including a crosslinking agent in the second compound in Step S10 and selectively crosslinking the second layer by irradiating electron beams in Step S30.

Next, the lead sealant film according to the present invention can be manufactured by completely lapping the lead sealant film through a heat lapping process in step S40.

Meanwhile, in the method of manufacturing a lead sealant film according to the present invention, the coextruded lead sealant film is irradiated with an electron beam (S30) and then subjected to a heat laminating process (S40), but the present invention is not limited thereto. The electron beam can be irradiated (S30).

Hereinafter, the present invention will be described in more detail by way of examples.

Example

Examples are prepared by mixing ter-ppp (PP-PE-MAH), Ethylene-Butylene Rubber (EBR) and LLDPE to prepare a first compound and a second compound, A third compound was prepared by mixing ethylene-butylene rubber (EBR) and ethylene-vinyl acetate copolymer (EVA). Here, a crosslinking agent (trimethylolpropane methacrylate) and a phenolic antioxidant were added to the second compound in an amount of 0.2 parts by weight based on 100 parts by weight of the second compound.

Next, the first compound, the second compound and the third compound were laminated in order and co-extruded to prepare a film.

Then, the produced film was irradiated with an electron beam, and a lead sealant film according to an embodiment of the present invention was produced through a heat lapping process.

Comparative Example

In Comparative Examples, the same first compound, second compound and third compound were prepared in the examples, and the first compound second compound and the third compound were laminated in order and co-extruded to prepare a film.

Here, a crosslinking agent (trimethylolpropane methacrylate) and a phenolic antioxidant were added to the second compound in an amount of 0.8 parts by weight based on 100 parts by weight of the second compound.

Table 1 below shows the tensile properties of the lead sealant films according to Examples and Comparative Examples.

Comparative Example Example 100 탆 150 100 150 Yield strength MD 13.82 N / mm < 2 & 14.20 N / mm < 2 & 21.33 N / mm < 2 > 22.12 N / mm < 2 > TD 12.32 N / mm < 2 & 13.11 N / mm < 2 > 20.38 N / mm < 2 & 21.01 N / mm < 2 > The tensile strength MD 23.45 N / mm < 2 & 24.21 N / mm < 2 & 40.77 N / mm < 2 & 50.00 N / mm < 2 & TD 22.22 N / mm < 2 > 21.21 N / mm < 2 & 39.18 N / mm < 2 & 38.18 N / mm < 2 > Elongation MD 425.05% 432.76% 708.50% 777.99% TD 423.03% 412.76% 806.77% 796.49%

Referring to Table 2, the tensile properties of Examples and Comparative Examples were analyzed.

On the other hand, the yield strength is related to the stiffness of the film, and the appropriate range is 15 ~ 40 N / ㎟ considering the processability (film supply, heat welding process, softness etc).

As a result of measuring the yield strengths of the examples and comparative examples, it was confirmed that the examples had a yield strength of 15 to 40 N / mm 2, but the comparative example was lower than 15 N / mm 2 there was.

Considering the manufacturing processability, the appropriate tensile strength is 30 ~ 60 N / mm < 2 >, and the elongation is 500~1000%. The example satisfies all of the appropriate tensile strength and elongation while the comparative example has a tensile strength of 30N / And the elongation was 500% or less.

That is, although Examples and Comparative Examples can prevent the oxidation of the lead sealant film prepared by adding the phenolic antioxidant, the tensile properties of the comparative examples are significantly lower than those of the Examples.

It should be noted that the embodiments disclosed in the drawings are merely examples of specific examples for the purpose of understanding, and are not intended to limit the scope of the present invention. It will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention are possible in addition to the embodiments disclosed herein.

10: Secondary battery 20: Case
21: Case body 22: Case cover
30: electrode assembly 40: positive electrode tab
50: cathode electrode tab 60: anode electrode lead
70: cathode electrode lead 80: lead sealant film
81: first layer 82: second layer
83: Third floor

Claims (6)

A first layer comprising an acid-modified copolymer, an ethylenic elastomer and a low-density polyolefin;
A second layer joined on the first layer and comprising an acid-modified copolymer, an ethylenic elastomer, a low-density polyolefin, a crosslinking agent and a phenol-based antioxidant; And
A third layer bonded on the second layer and comprising an acid-modified copolymer, an ethylenic elastomer, and a vinyl-based copolymer; / RTI >
Wherein the cross-linking agent comprises at least one member selected from the group consisting of trimethylolpropane methacrylate, pentaerythritol triacrylate, etchrecoll dimethacrylate, triallyl cyanurate and triarylisocyanurate,
Wherein the phenolic antioxidant comprises 0.1 to 0.4 parts by weight based on 100 parts by weight of the compound contained in the second layer. The method according to claim 1,
Wherein said acid-modified copolymer comprises at least one of maleic anhydride modified polypropylene, maleic anhydride modified polyethylene, carboxylic acid modified polypropylene, carboxylic acid modified polyethylene, acrylic modified polypropylene and acrylic modified polyethylene. Sealant film. The method according to claim 1,
Wherein the ethylenic elastomer comprises at least one of ethylene propylene rubber (EPDM) and ethylene propylene copolymer (EPR). The method according to claim 1,
Wherein the low density polyolefin comprises at least one of low density polyethylene (LDPE) and linear low density polyethylene (LLDPE). The method according to claim 1,
Wherein the ratio of the acid-modified copolymer to the total weight part of the first layer is 20% or more. An electrode assembly including a plurality of electrode tabs;
A plurality of electrode leads connected to the plurality of electrode tabs and exposed to the outside;
A lead sealant film attached to at least one side of each of the plurality of electrode leads;
A case for accommodating the electrode assembly in a state that a part of the plurality of electrode leads is exposed to the outside; Lt; / RTI >
Wherein the lead sealant film is bonded between the electrode lead and the case and has a first layer comprising an acid-modified copolymer, an ethylenic elastomer and a low-density polyolefin, an acid-modified copolymer bonded to the first layer, A second layer comprising an elastomer, a low-density polyolefin, a crosslinking agent and a phenol-based antioxidant, and a third layer bonded on the second layer and comprising an acid-modified copolymer, an ethylenic elastomer and a vinyl-
Wherein the cross-linking agent comprises at least one member selected from the group consisting of trimethylolpropane methacrylate, pentaerythritol triacrylate, etchrecoll dimethacrylate, triallyl cyanurate and triarylisocyanurate,
Wherein the phenolic antioxidant comprises 0.1 to 0.4 parts by weight based on 100 parts by weight of the compound contained in the second layer.

Images