KR101686961B1 - Seal tape, preparation method thereof and lithium secondary battery comprising the same - Google Patents

Abstract

The present invention relates to a laminate comprising a melt adhesive layer, a polymer base film layer, and a pressure-sensitive adhesive layer laminated in this order, and even when compressed at a temperature of less than 100 ° C, the adhesion strength of the battery pouch with the polymer coating layer is 300 gf / And a lithium secondary battery including the same.

Description

TECHNICAL FIELD [0001] The present invention relates to a thermally compression-bonded tape, a method of manufacturing the same, and a lithium secondary battery including the same. BACKGROUND ART [0002]

The present invention relates to a thermally compression-bonded tape, a method of manufacturing the same, and a lithium secondary battery including the same. More particularly, the present invention relates to a thermally crimped finish tape which is disposed between an electrode assembly and a pouch in a pouch type lithium ion secondary battery so that an electrode assembly is not separated from a pouch even when an impact is applied to the cell, The present invention relates to a secondary battery.

BACKGROUND ART Generally, in manufacturing a lithium ion secondary battery, an outer surface of an electrode assembly is wrapped with a tape to hold an electrode assembly (also referred to as a 'jelly roll') so as not to be loosened so as to accommodate the electrode assembly in a cylindrical or pouch-shaped battery case. That is, the tape is attached in a state of wrapping the outer surface of the electrode assembly in which the positive electrode plate, the separator, and the negative electrode plate are stacked in order. Generally, such a tape is called a finished tape.

In the pouch-type lithium ion secondary battery (polymer battery), an electrode assembly is placed in a battery case of a pouch type. When an impact is applied to the battery due to dropping or the like, the electrode assembly flows in the pouch, Explosion or the like occurs. Accordingly, a finishing tape having a special function between the electrode assembly and the pouch should be disposed so that the electrode assembly does not flow in the pouch even if the battery is impacted.

Generally, a finish tape used in a pouch-type secondary battery is formed by using a finish tape coated with an acrylic pressure sensitive adhesive (PSA) on a polypropylene (OPP) or polyethylene terephthalate (PET) The PP or PET layer of the tape is pressed against the coated surface.

In the case of some commercially available PP films, a sufficient adhesion may be caused by pressing at a temperature of 140 ° C or higher. However, when the electrolyte used in the lithium ion secondary battery receives heat of 120 ° C or more, electrolyte dissolved in the electrolyte precipitates, resulting in deterioration of the performance of the battery. On the other hand, when the finishing tape is squeezed at a temperature of 100 ° C or higher, a part of the electrolyte is vaporized to generate air bubbles inside the cell, and the pressure caused by the generated air bubbles presses the jelly roll to reduce the life of the battery .

Therefore, in order to solve the above problems, it is necessary to exhibit a sufficient adhesive force even when it is squeezed at a low temperature of less than 100 ° C, and ideally it is necessary to develop a thermosetting tape which can be adhered at 80 ° C or less.

Patent Document 1: Korean Patent Publication No. 10-2011-0127830A (Published on November 28, 2011 "Secondary Battery") Patent Document 2: Korean Patent Laid-Open Publication No. 10-2012-0013877A (Published on February 15, 2012 "Secondary Battery")

An object of the present invention is to prevent the electrode assembly from flowing in a pouch in a pouch type lithium ion secondary battery.

It is another object of the present invention to provide a thermally crimped finishing tape capable of preventing an electrode assembly from flowing in a pouch, a method for manufacturing the same, and a lithium secondary battery comprising the same.

Another object of the present invention is to provide a thermally compression-bonded tape capable of exhibiting a sufficient adhesive force even when it is compressed at a low temperature of less than 100 캜 while satisfying the above-mentioned object.

The above-described object of the present invention is achieved by the following means.

1. A thermally pressed finish tape laminated in this order of a hot melt adhesive layer, a polymer substrate film layer and a pressure sensitive adhesive layer.

2. The thermally pressed finish tape 1, wherein the thickness of the hot melt adhesive layer is 1 to 50 占 퐉, the thickness of the polymer base film layer is 1 to 75 占 퐉, and the thickness of the pressure sensitive adhesive layer is 1 to 25 占 퐉.

3. The thermally pressed finish tape of 1 above, wherein the hot-melt adhesive layer comprises an adhesive having a melting temperature of 60 DEG C or lower.

4. The thermally pressed finish tape of 3 above, wherein said adhesive comprises ethylene vinyl acetate, polyolefin and synthetic butadiene rubber.

5. The thermally pressed finish tape of 1 above, wherein the polymer is at least one selected from the group consisting of polyethylene, polypropylene, polyethylene terephthalate, polycarbonate, polymethylmethacrylate, polyurethane and polyimide.

6. The hot-pressed adhesive tape of 1 above, wherein the hot-melt adhesive layer has an adhesion of 300 pg / in or more to the polymer coating layer of the cell pouch during compression at a temperature of less than 100 ° C.

7. The thermally pressed finish tape of the above 1, wherein the pressure-sensitive adhesive layer comprises an acrylic pressure-sensitive adhesive.

Wherein the acrylic pressure-sensitive adhesive is selected from the group consisting of butyl acrylate, ethyl acrylate, methyl methacrylate, vinyl acrylate, 2-ethylhexyl acrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, glycidyl methacrylate, Ethylene glycol dimethacrylate, ethylene glycol dimethacrylate, and ethylene glycol dimethacrylate, and acrylic acid.

9. A pouch-type lithium secondary battery comprising the thermocompression-bonded tape according to any one of 1 to 8 above.

10. The pouch-type mold according to the above 9, wherein the pressure-sensitive adhesive layer of the thermo-compression-finishing tape is in contact with the electrode assembly, and the hot-melt adhesive layer is in contact with the pouch, Lithium secondary battery.

11. A method of increasing the adhesion force to at least 300 gf / in at the time of thermocompression at a temperature below 100 DEG C, comprising forming a hot melt adhesive coating layer on the polymer substrate film.

12. The method of 11 above, wherein said hot melt adhesive layer comprises an adhesive having a melting temperature of < RTI ID = 0.0 > 60 C < / RTI >

13. The method of claim 12, wherein the adhesive comprises ethylene vinyl acetate, a polyolefin, and a synthetic butadiene rubber.

14. The method of 11 above, wherein the polymer is at least one selected from the group consisting of polyethylene, polypropylene, polyethylene terephthalate, polycarbonate, polymethylmethacrylate, polyurethane and polyimide.

A pouch-type lithium ion secondary battery according to the present invention is provided with a thermally compression-finished tape disposed between an electrode assembly and a pouch to prevent an electrode assembly from being separated from a pouch even when an impact is applied to the battery, a method for manufacturing the same, and a secondary battery comprising the same. .

The thermally compression-finished tape according to the present invention can prevent the electrode assembly from flowing in the pouch when the battery is repeatedly dropped. Therefore, unlike an existing battery, even if an impact is applied to the battery, a short circuit, ignition, explosion, . ≪ / RTI >

In addition, since the thermally crimped finishing tape according to the present invention can exhibit sufficient adhesion even when it is compressed at a low temperature of less than 100 캜, it is not necessary to press the finishing tape at a high temperature of 100 캜 or higher in producing a pouch- , It is possible to prevent a rise in internal pressure of the battery due to bubbles generated by vaporization of a part of the electrolytic solution at the time of high-temperature thermocompression bonding and a reduction in the life of the battery.

1 is a schematic view of a pouch type secondary battery to which a finishing tape including a PP film is applied according to the prior art.
2 is a schematic view of a pouch-type secondary battery to which a thermally compression-bonded tape according to an embodiment of the present invention is applied.

The present invention relates to a thermally compression-finished tape capable of securing sufficient adhesion even when thermocompression is performed at a temperature of less than 100 ° C, a method for producing the same, and a lithium secondary battery comprising the same.

The thermocompression-bonded tape according to the present invention comprises a laminate laminated in this order of a hot-melt adhesive layer, a polymer-based film layer and a pressure-sensitive adhesive layer.

The hot-melt adhesive layer may have a thickness of 1 to 50 占 퐉, the polymer-based film layer may have a thickness of 1 to 75 占 퐉, and the pressure-sensitive adhesive layer may have a thickness of 1 to 25 占 퐉. The total thickness of the thermally bonded finish tape comprising these laminate layers can be up to 150 [mu] m depending on the application.

Wherein the hot melt adhesive layer comprises an adhesive having a melting temperature of 60 DEG C or lower. As a finishing tape for a lithium secondary battery, a pressure-sensitive adhesive layer is coated on one side of a commercial polypropylene (PP) base film. In the case of some commercially available PP films, it is possible to secure an adhesion force of 300 gf / in or higher by pressing at a high temperature of 140 캜 or higher. However, when the lithium secondary battery receives heat of 100 占 폚 or more, a part of the electrolyte is vaporized and air bubbles are generated inside the battery, and the resulting inner pressure presses the jelly roll to reduce the life of the battery. For use as a tape, thermocompression should be possible at temperatures below 100 ° C. In the present invention, a hot-melt adhesive layer containing an adhesive having a melting temperature of 60 占 폚 or less is coated on a polymer base film, whereby adhesion by thermocompression at a low temperature of less than 100 占 폚 becomes possible. Therefore, when applying the finishing tape according to the present invention to a battery, even if a repeated impact is applied to the battery, an adhesive force sufficient to prevent the electrode assembly from flowing in the battery pouch, preferably an adhesive force of 300 gf / .

The adhesive included in the hot melt adhesive layer includes ethylene vinyl acetate, polyolefin and synthetic butadiene rubber, preferably 40 wt% or less of ethylene vinyl acetate, 40 wt% or less of a polyolefin, preferably polyethylene and / or polypropylene And a mixture of 20 wt% or more of synthetic butadiene rubber. Specific examples of the hot melt adhesive include, but are not limited to, a commercial hot melt chip (manufactured by Chemtec Korea), and an adhesive having a melting temperature of 60 占 폚 or less, Anything can be used.

As the polymer base film, any material can be used as long as it is made of a material which can be used as a base material of a finishing tape. The polymer may preferably be one or more selected from the group consisting of polyethylene, polypropylene, polyethylene terephthalate, polycarbonate, polymethylmethacrylate, polyurethane and polyimide.

On the thermocompression-bonded tape according to the present invention, a pressure sensitive adhesive layer is laminated on one side of the polymer base film on which the hot melt adhesive layer is not coated. The pressure-sensitive adhesive layer may be formed using a conventional pressure sensitive adhesive, preferably an acrylic pressure-sensitive adhesive, more preferably butyl acrylate, ethyl acrylate, methyl methacrylate, vinyl acrylate, 2-ethylhexyl acrylate, hydroxyethyl acrylate, But are not limited to, acrylic acid, acrylic acid, hydroxyethyl methacrylate, glycidyl methacrylate, triethylene glycol dimethacrylate, and acrylic acid. Any of acrylic pressure-sensitive adhesives can be used.

The present invention also relates to a pouch type lithium secondary battery comprising the above-mentioned thermally compression-bonded tape. The pouch-type lithium secondary battery according to the present invention has a configuration of a conventional lithium secondary battery except that the electrode assembly and the battery pouch are attached by applying the above-mentioned thermally compression-bonded tape. For example, the pouch-type lithium secondary battery is laminated in the order of an electrode assembly, a thermally press-coated finish tape, and a pouch, and the pressure-sensitive adhesive layer of the thermosetting finish tape is in contact with the electrode assembly and the hot melt adhesive layer is in contact with the pouch Lt; / RTI >

The present invention also relates to a method of enhancing the adhesion force to 300 gf / in or more at the time of thermocompression at a temperature of less than 100 캜, including forming a hot melt adhesive coating layer on a polymer substrate film. Here, the hot melt adhesive layer includes an adhesive having a melting temperature of 60 DEG C or lower, preferably an adhesive comprising ethylene vinyl acetate, a polyolefin and a synthetic butadiene rubber.

Example

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. The present invention is intended to more specifically illustrate the present invention, and the scope of the present invention is not limited to these embodiments.

Manufacture of thermo-compression finished tape

Example 1

A hot melt solution was prepared by mixing 35% by weight of a hot melt chip (manufacturer: Chemtech Korea, product name: V7523) and 65% by weight of toluene. A commercially available polypropylene film (BT Grade, manufactured by Philax) having a thickness of 15 탆 was applied as a base film to an appropriate amount on one side of the prepared solution, and a coating film was formed using a comma coater. Followed by drying for a minute to produce a PP film coated with a hot melt adhesive layer.

A solution obtained by mixing 100 parts by weight of an acrylic pressure-sensitive adhesive (manufacturer: Saneon, product name: ATL-30), 0.6 parts by weight of toluene diisocyanate and 70 parts by weight of toluene was applied to a release film (XP3BR Grade, To form a coating film, which was then dried in an oven at 120 캜 for 3 minutes to form a pressure-sensitive adhesive layer having a thickness of 5 탆.

The pressure-sensitive adhesive layer thus prepared was transferred to a film surface on which the hot-melt adhesive layer of the hot-melt coating film prepared in the above was not formed to produce a finish tape.

Example 2

A finish tape was prepared in the same manner as in Example 1, except that a commercially available polypropylene film (CPT Grade, manufacturer: Pillmax) having a thickness of 40 탆 was used as a base film.

Example 3

A finish tape was prepared in the same manner as in Example 1 except that a commercially available polyethylene terephthalate film (XP37 Grade, manufactured by Toray Industries, Ltd.) having a thickness of 25 탆 was used as a base film.

Example 4

A finishing tape was produced in the same manner as in Example 1 except that a commercially available polyimide film (IF Grade, manufacturer: SKK CORPORATION) having a thickness of 25 mu m was used as a base film.

Comparative Example 1

A solution obtained by mixing 100 parts by weight of an acrylic pressure-sensitive adhesive (manufacturer: Saneon, product name: ATL-30), 0.6 parts by weight of toluene diisocyanate and 70 parts by weight of toluene was applied to a release film (XP3BR Grade, To form a coating film, which was then dried in an oven at 120 캜 for 3 minutes to form a pressure-sensitive adhesive layer having a thickness of 5 탆.

The pressure-sensitive adhesive layer thus prepared was transferred to one side of the film using a commercially available propylene film (BT Grade, manufacturer: PILLMAX) having a thickness of 15 μm used as a base material for a lithium ion secondary battery, Respectively.

Comparative Example 2

A finish tape was prepared in the same manner as in Comparative Example 1, except that a 40 μm thick commercial polypropylene film (CPT Grade, manufactured by PILLMAX) used as a base material for a lithium ion secondary battery tape was used as a base film.

Comparative Example 3

A finish tape was produced in the same manner as in Comparative Example 1, except that a commercially available polyethylene terephthalate film (XP37 Grade, manufactured by Toray Industries, Ltd.) having a thickness of 25 μm used as a base material for a tape for a lithium ion secondary battery was used as a base film Respectively.

Comparative Example 4

A finish tape was produced in the same manner as in Comparative Example 1, except that a 25 μm thick commercial polyimide film (IF Grade, manufacturer: SKK CORPORATION) used as a base material for a tape for a lithium ion secondary battery was used as a base film Respectively.

Adhesion evaluation

The finishing tape prepared in Examples and Comparative Examples was cut to a width of 1 inch and a length of 1500 mm and the pressure sensitive adhesive layer of the finishing tape was placed in contact with the aluminum electrode plate for the secondary battery. Then, the 2 kg pressing roller was rotated at a speed of 300 mm / min And the finish tape was attached to the aluminum electrode plate.

Then, 0.1 g of an electrolytic solution (product name: Starlyte, manufactured by Panax Electronic Co., Ltd.) was applied to the hot-melt thermocompression side of the finishing tape, and the surface coated with the electrolyte was placed in contact with the inner surface of the battery pouch. The test specimens were prepared by pressing the specimens with a length of 25 cm and a length of 25 cm at a pressure of 10 kg for 20 seconds.

The force (adhesive force) required to peel the finished tape specimen from the pouch at 180 ° at a speed of 300 ± 30 mm / min was measured using a universal testing machine (UTM). Table 1 below shows the adhesion force measurement (gf / in).

Example Comparative Example Thermocompression temperature One 2 3 4 One 2 3 4 60 ° C 0 0 0 0 0 0 0 0 70 ℃ 454 435 461 446 0 0 0 0 80 ℃ 521 550 544 512 0 0 0 0 90 ° C 603 620 661 652 0 0 0 0 100 ℃ 718 709 714 716 0 0 0 0 110 ° C 793 804 795 810 0 0 0 0 120 DEG C 864 866 841 859 0 0 0 0

As shown in Table 1, the tapes prepared in the examples of the present invention exhibit an adhesive force of 300 gf / in or more even when thermocompression is performed at a temperature of less than 100 캜, which is sufficient for use as a low-temperature thermosetting finish tape. This is because, in the embodiment of the present invention, the hot melt adhesive having a melting temperature of about 60 캜 is used to melt the surface even when pressed at a temperature of less than 100 캜 to exert a sufficient adhesive force.

On the contrary, as in Comparative Examples 1 to 4, a finish tape to which a commercial polypropylene film used as a base material of a finish tape for a lithium secondary battery was applied had sufficient adhesion at a temperature of 140 ° C or higher. However, . Thus, the finish tape produced in the comparative example can be used when there is no problem even at high temperature hot pressing at 140 ° C. or more. However, when hot pressing is required at a low temperature of less than 100 ° C., for example, It can be seen that it can not be applied as a finishing tape when it is adhered by an al bonding method.

The present invention has been described above by way of examples. It will be understood by those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are only illustrative of the present invention and are not intended to limit the scope of the invention. The scope of the present invention is defined by the appended claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention.

10: Pouch
11: Aluminum foil
12: Polypropylene coating
20: Finishing tape 21: polymer-based film layer
22: Pressure sensitive adhesive layer 23: Hot melt adhesive layer
30: Electrode assembly (jelly roll)

Claims (14)

A hot melt adhesive layer comprising ethylene vinyl acetate, polyolefin and synthetic butadiene rubber; A polymer based film layer; And a pressure-sensitive adhesive layer,
Wherein the hot melt adhesive layer has a melting temperature of 60 占 폚 or lower
Thermal pressed tape for pouch type secondary battery. The method according to claim 1,
Wherein the thickness of the hot-melt adhesive layer is 1 to 50 占 퐉, the thickness of the polymer-based film layer is 1 to 75 占 퐉, and the thickness of the pressure-sensitive adhesive layer is 1 to 25 占 퐉. delete delete The method according to claim 1,
Wherein the polymer is at least one selected from the group consisting of polyethylene, polypropylene, polyethylene terephthalate, polycarbonate, polymethylmethacrylate, polyurethane and polyimide. The method according to claim 1,
Wherein the hot melt adhesive layer has an adhesive strength of 300 gf / in or more to the polymer coating layer of the battery pouch when compressed at a temperature of less than 100 캜. The method according to claim 1,
Wherein the pressure-sensitive adhesive layer comprises an acrylic pressure-sensitive adhesive. 8. The method of claim 7,
The acrylic pressure sensitive adhesive may be at least one selected from the group consisting of butyl acrylate, ethyl acrylate, methyl methacrylate, vinyl acrylate, 2-ethylhexyl acrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, glycidyl methacrylate, Glycol dimethacrylate, and acrylic acid. The thermally compression-finished tape for a pouch type secondary battery according to claim 1, A pouch type lithium secondary battery comprising the thermally compression-bonded tape for a pouch type secondary battery according to any one of claims 1, 2, and 5 to 8. 10. The method of claim 9,
Wherein the pressure sensitive adhesive layer of the thermosetting finish tape is in contact with the electrode assembly and the hot melt adhesive layer is contacted with the pouch. The pouch type lithium secondary battery according to claim 1, wherein the pouch type lithium secondary battery is a pouch type lithium secondary battery. A process for producing a hot melt adhesive coating layer on a polymer substrate film comprising the steps of: applying a finish tape and a release layer on a polymer substrate film during thermal compression at a temperature below 100 DEG C, comprising forming a hot melt adhesive coating layer comprising ethylene vinyl acetate, a polyolefin and a synthetic butadiene rubber, A method for improving the adhesion force with a secondary battery pouch to 300 gf / in or more. delete delete 12. The method of claim 11,
Wherein the polymer is at least one selected from the group consisting of polyethylene, polypropylene, polyethylene terephthalate, polycarbonate, polymethylmethacrylate, polyurethane and polyimide.

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