KR100887616B1 - Pouch for packing cell and method for preparing the same - Google Patents

Abstract

The present invention relates to a cell pouch and a method of manufacturing the same, wherein at least one layer of a thermochromic ink layer discolored with temperature is present in a laminated configuration of the cell pouch. According to the cell pouch of the present invention, it is possible to ensure the stability and reliability of the cell by allowing the cell pouch itself to express an abnormal increase in the internal temperature of the cell due to an overcharge or an internal short circuit caused by an abnormal reaction in the cell. In addition, the cell pouch of the present invention is short and light in manufacturing time, free in shape, and excellent in heat resistance, electrical insulation, moisture proof and gas barrier properties, stability, chemical resistance, heat seal strength, and moldability.

Lithium Battery, Storage Battery, Cell Pouch, Temperature, Discoloration, Ink, Temperature, Microcapsules

Description

Pouch for packing cell and method for preparing the same

1 to 6 is a schematic diagram showing a laminated configuration of a cell pouch according to embodiments of the present invention.

* Short description of the major reference marks *

10: outermost layer film 20: thermochromic ink layer

21: mixed layer of thermochromic ink and adhesive 25: ink layer

30 barrier layer 40 sealant layer

a: polyester film b: polyamide film

The present invention relates to a cell pouch such as a lithium secondary battery or a portable storage battery, and a manufacturing method thereof.

As cell packaging materials for lithium secondary batteries, portable storage batteries and the like, packaging materials formed by pressing a metal, in particular aluminum, into a cylindrical or parallelepiped shape or the like have been mainly used. However, in the case of such a metal can packaging material, the outer wall of the container is hard so that the shape of the battery itself is determined by the shape of the metal can packaging material.

To overcome this limitation, stacked cell pouch technology has been developed. For example, Korean Patent Application No. 2003-7002427 discloses a cell pouch consisting of a base layer, an adhesive layer, a barrier layer, a dry lamination layer, and a sealant layer, wherein the sealant layer is composed of a low flow polypropylene layer and a high flow polypropylene layer. . In addition, Korean Patent Publication No. 2002-0030737 discloses a cell pouch structure laminated using biaxially stretched nylon, polyethylene terephthalate (PET), and a polyolefin resin on a base film and a surface protective layer.

In these conventional techniques, gas or moisture barrier properties, moldability, electrolyte resistance, and the like have been considered.

However, in the conventional cell pouch, a method for securing the stability or reliability of the cell has not been developed by sensing an overcharge due to an abnormal reaction in the cell or an internal temperature of the cell due to an internal short.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is a cell pouch such as a lithium secondary battery or a portable storage battery. It is to provide a cell pouch and a method of manufacturing the cell pouch which can ensure the stability and reliability of the cell by allowing the cell pouch itself to express abnormally rising.

It is also an object of the present invention to provide a cell pouch having a short manufacturing time and a light weight, having a free shape, and excellent in heat resistance, electrical insulation, moisture resistance and gas barrier property, stability, chemical resistance, heat sealing strength, and formability, and a method of manufacturing the same. It is.

The object of the present invention described above is achieved by a cell pouch in which at least one layer of a thermochromic ink layer discolored in accordance with temperature in a laminated configuration of a cell pouch and a manufacturing method thereof.

In one embodiment of the present invention, the thermochromic ink includes a thermochromic microcapsules, wherein the thermochromic microcapsules preferably have a particle diameter greater than 0 µm and 3 µm or less.

In one embodiment of the present invention, the thermochromic microcapsules having a particle diameter of more than 0 μm and 3 μm or less are preferably contained in an amount of 50 wt% or more and 100 wt% or less based on the total micro capsules.

In one embodiment of the present invention, the thermochromic ink is a thermochromic microcapsules 10 to 40 parts by weight; 20 to 40 parts by weight of acrylic or urethane resin; And 30 to 50 parts by weight of the solvent.

In one embodiment of the present invention, the thermochromic inks, 1 to 5 parts by weight of one or more additives selected from the group consisting of wax, colorant, antifoaming agent, slip agent, pH adjuster, heat reinforcing agent; 10 to 40 parts by weight of the capsule; 20 to 40 parts by weight of acrylic or urethane resin; And 30 to 50 parts by weight of the solvent; It is preferably further included in the thermochromic ink.

In one embodiment of the present invention, the solvent is preferably composed of 25 to 60% by weight of water, 20 to 60% by weight of ethanol, 5 to 20% by weight of any one or both of methanol or isopropyl alcohol. Do.

In one embodiment of the present invention, the solvent is an organic solvent, it is preferable that toluene is contained in 65% by weight or more and 100% by weight or less.

In one embodiment of the present invention, the thermochromic ink layer is 20 to 40% by weight of the thermochromic ink; And it is preferable that it is a mixed layer of the thermochromic ink and adhesive which consist of 60-80 weight% of adhesives.

In one embodiment of the invention, the cell pouch, the outermost layer film; A barrier layer below the outermost layer film; And a sealant layer that is an innermost layer below the barrier layer, wherein the uppermost layer of the outermost layer, between the outermost layer and the barrier layer, and when the outermost layer is formed of a laminate of a plurality of films, It is preferable that the thermochromic ink layer is formed at any one or more positions selected from the group consisting of two films.

In one embodiment of the present invention, it is preferable that an ordinary ink layer is formed on one or both of the upper or lower portions of the thermochromic ink layer.

In one embodiment of the present invention, it is preferable that an adhesive layer is formed on one or both of the upper or lower portion of the thermochromic ink layer.

In one embodiment of the present invention, the outermost layer film is preferably a polyamide film or a polyester film or a laminated film of a polyester film and a polyamide film.

In one embodiment of the present invention, the outermost layer film is preferably a polyester film containing an acid component of 100 to 110 mol parts with respect to 130 mol parts of the glycol component.

In one embodiment of the present invention, the barrier layer is preferably made of aluminum foil, more preferably a non-chromate-based corrosion protection layer is formed on both sides of the aluminum foil, the aluminum foil comprises silicon and iron at the same time However, the content is more preferably 0.05 to 0.9% by weight and 0.6 to 2.0% by weight, respectively.

In one embodiment of the present invention, it is preferable that any one or two of an adhesive layer or a melt extrusion resin layer is formed in order between the barrier layer and the sealant layer that is the innermost layer, and the melt extrusion resin layer is ozone treated. More preferably.

In one embodiment of the present invention, the sealant layer which is the innermost layer is preferably made of modified polypropylene.

In one embodiment of the invention, the innermost sealant layer is an oxide of SiO ₂ or Al ₂ O ₃ or a group consisting of Cu, Fe, Sn, Zn, Ag and Al on a polyolefin film consisting of a single layer or a multilayer It is preferable that a deposition layer of a metal, which is any one selected from, is formed.

In one embodiment of the present invention, the thickness of the deposited layer is preferably 200 to 500 kPa.

In one embodiment of the present invention, it is preferable that the sealant layer and the barrier layer on which the oxide or metal deposition layer is formed are bonded by a urethane-based adhesive resin.

In one embodiment of the present invention, the polyolefin film is a polyolefin film formed of three layers, it is preferable that two adjacent polyolefins of the polyolefin film formed of the three layers are polyolefins having different crystallinity.

EMBODIMENT OF THE INVENTION Hereinafter, the cell pouch which concerns on this invention, and its manufacturing method are explained in full detail.

In the present invention, in the cell pouch, in particular, by including a thermochromic ink layer composed of ink which changes color according to the temperature in the laminated structure of the cell pouch, the internal temperature of the battery becomes abnormal due to overcharge or internal short circuit caused by abnormal reaction in the cell. By allowing the cell pouch itself to express the rise, it is possible to secure the stability and reliability of the cell. Further, by using the thermochromic ink layer, it is also possible to directly check whether the cell and the electrolyte are put in the cell pouch and sealed at an appropriate temperature in the process of sealing the cell pouch.

1 to 6 is a schematic diagram showing a laminated configuration of a cell pouch according to embodiments of the present invention. For reference, although the adhesive layer, the melt-extruded resin layer, the corrosion prevention layer and the like are not separately illustrated in FIGS. 1 to 6, they are additionally formed based on the configuration of FIGS. 1 to 6 as described below.

The cell pouch according to the embodiment of the present invention is laminated with the outermost layer film 10, the thermochromic ink layer 20, the barrier layer 30, and the sealant layer 40 in order (see FIG. 1). At this time, the opening position of the thermochromic ink layer 20 and the outermost layer film 10 can be changed so that the upper and lower sides (see Fig. 2), if the outermost layer film is two layers (a layer and b layer) In the case where the film is laminated, the film may be formed between the laminated films (see FIG. 3). Furthermore, the thermochromic ink layer may be opened as a mixed layer 21 of thermochromic ink and an adhesive in which an adhesive is mixed (see FIG. 4).

Meanwhile, an ordinary ink layer 25 may be additionally formed under the thermochromic ink layer 20 (see FIG. 5). In this case, the thermochromic ink layer 20 and the ordinary ink layer 25 may be additionally formed. It is also possible for the opened positions of to change their positions (see FIG. 6).

Hereinafter, each layer is explained in full detail.

As the outermost layer film 10, a polyester film (a) having excellent electrolyte resistance is used alone, or a polyamide film (b) capable of reinforcing moldability is used alone, or the polyester film (a) is used. The polyamide film (b) can be laminated (the order of lamination can be changed), and a polyester film having both electrolyte resistance and moldability can be used as described later.

The polyester film (a) is excellent in electrolyte resistance, and usable polyester film resins include, for example, polyethylene terephthalate (PET), poly butylene terephthalate (PBT), and polyethylene naphthalate. One or more selected from the group consisting of (polyethylene naphthalate; PEN), poly butylene naphthalate (PBN), copolyester, polycarbonate (PC) and the like are used.

In order for the polyester film to effectively protect the surface of the packaging material, the thickness of the film is generally 1.2 μm to 25 μm, preferably 1.2 μm to 9.0 μm.

The polyamide film (b) is for reinforcing moldability, which is particularly required for pouches of the molding type. In the case of the molding type, a biaxially stretched polyamide (Polyamides) film is used in consideration of the capacity and size of the battery. Examples of the biaxially stretched polyamides film resin include nylon 6, nylon 6.6, copolymers of nylon 6 and nylon 6.6, nylon 6.10, polymethacrylylene amidamide (MXD 6), and the like. Use one or more selected from. The thickness of the polyamide film is 15 to 50 μm, preferably 15 to 25 μm.

The polyester film (a) and the polyamide film (b) are laminated to each other and further through the adhesive of the polyamide film (b) and its lower layer. In this case, it is preferable to use a polyurethane adhesive having excellent heat resistance, and in particular, to use a urethane base two-component adhesive. Since the high temperature due to heat generation occurs during the movement of the battery in the inner-packed cells, in the case of adhesives having low heat resistance, the polyester film (a) and the polyamide film (b) and the polyamide film (b) and the lower layer It is necessary to use an adhesive having excellent heat resistance since liver separation occurs.

The heat resistance of the adhesive is measured by checking whether or not separation occurs after being put in a dry oven adjusted to a constant temperature in a laminated state or in a commercialized state, after a predetermined time. In general, the heat resistance of the adhesive is used that does not occur layer separation after 5 seconds at 150 ℃ or more than 10 seconds at 260 ℃.

On the other hand, in addition to using the laminated film of a polyester film and a polyamide film as above-mentioned as the outermost layer film, the film which has all the required characteristic of a polyester film and a polyamide film can be used.

As such a film, a polyester film containing an acid component in an amount of 100 to 110 moles per 130 moles of the glycol component is used. As described above, the polyester film in which the molar ratio of the acid component is adjusted with respect to the glycol component has moldability, moisture permeability, impact resistance, air (oxygen) permeation resistance, puncture strength, and electrolyte resistance It is excellent and satisfies all the required properties without the simultaneous use of a polyester film and a polyamide film, and is particularly suitable as the outermost film of a cell pouch.

The glycol component of the polyester film in which the molar ratio of the acid component to the glycol component is controlled is, for example, propane diol, and the acid component is, for example, dimethyl terephthalate, terephthalic acid, naphthalenedicarboxylic acid, isophthalic acid, adipic acid or the like. An additive such as a catalyst, a slip agent, a stabilizer, and the like may be added to the polyester film in which the molar ratio of the acid component to the glycol component is controlled. In particular, the slip agent increases the slip properties, thereby reducing the coefficient of friction during molding to facilitate molding, and when the friction coefficient is large, a break point is formed to be short, thereby preventing the problem of cracking of aluminum. The polyester film in which the molar ratio of the acid component to the glycol component is controlled is particularly preferably a biaxially stretched film having excellent mechanical strength, and the thickness thereof is preferably 12 to 100 µm. In addition, it is preferable to use a corona treatment on the inner surface or both sides in order to enhance the adhesion.

Next, the thermochromic color ink layer 20 will be described in detail.

A thermochromic ink is an ink whose color changes with temperature, and the thermochromic ink absorbs energy and discolors (or discolors), and when the energy is blocked, the thermochromic ink returns to its original color or discolors to another color. Such thermochromic inks exist in various types depending on their color, discoloration temperature (the discolorable temperature is applicable at a wide temperature such as -30 to 120 ° C), discoloration mechanism, and the like.

In the present invention, in particular, by using the thermochromic ink, the ink layer is formed to grasp the thermal behavior of the cell through the cell pouch itself, thereby ensuring stability and reliability of the cell, and sealing at an appropriate temperature in the cell pouch sealing process. It is possible to directly check if this is possible.

In forming the thermochromic ink layer, the thermochromic dye is very sensitive to the external environment, it is preferable to protect it with a microcapsule. That is, a thermochromic microcapsules are formed by putting a thermochromic dye (chromic dye) inside and forming an outer wall such as melamine resin, formaldehyde, yeast, starch or dextrin.

In this case, when the number of layers of the outer wall is increased by a method of increasing the number of coatings, the outer wall may be further strengthened, thereby lowering the probability that the capsule is broken by the pressure during the printing process. Further, as a preparation of the thermochromic microcapsules, a method of capturing the thermochromic pigment using a yeast cell wall component and using a collecting solvent such as ethanol may be used (Korean Patent No. 429951).

The thermochromic microcapsules have a particle diameter of several micrometers, and in order to maintain printability, preservation, and color reproducibility, the microcapsule may have a small diameter in the range of several micrometers. In the present invention, in particular, the particle size of the thermochromic microcapsules is 3 µm or less, in which case printability, storageability and color reproducibility are excellent. Further, even if the particle size of the total thermochromic microcapsules has a particle size of 3 μm or less, only 50% by weight or more is good in printability, storageability, and color reproduction.

The particle size distribution control may be performed by removing or filtering relatively large particles larger than 3 μm through the mesh. By repeatedly performing such removal operations using a mesh, a desired particle size can be secured.

In the present invention, 10 to 40 parts by weight of the thermochromic microcapsules (solids), 20 to 40 parts by weight of an acrylic or urethane resin, and 30 to 50 parts by weight of a solvent are mixed and stirred for 10 to 20 minutes to prepare a thermochromic ink composition. Here, the thermochromic ink composition may be added in an amount of 1 to 5 parts by weight of any one or two or more additives of a wax, a colorant, an antifoaming agent, a slipping agent, a pH adjusting agent or a heat reinforcing agent.

The thermochromic microcapsules (solids) should be contained in the composition at 10 to 40 parts by weight as described above to improve color and transfer power. In other words, if less than 10 parts by weight color reproducibility is lowered, the distribution of capsules is lowered, the color does not change when the temperature changes, and if more than 40 parts by weight unnecessary excess addition without the advantage in color reproducibility, etc. It is not preferable because it rises.

 The solvent is an aqueous type or an oil type solvent.

The aqueous type solvent consists of 25 to 65% by weight of water, 20 to 60% by weight of ethanol, either 5 to 20% by weight of either or both of methanol or isopropyl alcohol, and the oily type of solvent is at least 65% by weight of toluene and the remainder is added. If present, other organic solvents such as MEK are comprised of up to 35% by weight.

Each type of solvent has a good resistance of the capsule to the solvent at the above composition ratio and there is no problem of solvent retention.

As described above with reference to FIGS. 1 to 3, the thermochromic ink layer 20 may be located at an upper position of the outermost layer film 10 or a position or outermost position between the outermost layer film 10 and the barrier layer 20. It may be formed at a position between the polyester film (a) and the polyamide film (b) of the outer layer film, and may be formed at two or more positions. At this time, the thermochromic ink layer 20 is applied by spray or by the coating method such as gravure, screen, offset, flexo, etc., the upper surface of the outermost layer film 10 or any one of the laminated films (a, b). Or on the lower surface or on the upper surface of the barrier layer 30. Printing roll making method for coating the thermochromic ink composition using a laser method to produce a plate at 150 to 200 lines at a depth of 26 to 46㎛ particularly good coating for capsules of 3㎛ or less The castle can be secured. When the thermochromic ink layer 20 is formed as described above, the outermost layer film 10 and the barrier layer 20 are laminated using, for example, a urethane-based adhesive having excellent heat resistance as described above.

As described with reference to FIG. 4, in the present invention, it is also possible to form the mixed layer 21 of the thermochromic ink and the adhesive by mixing the thermochromic ink composition with the adhesive.

As such, when the thermochromic ink and the adhesive are blended, it is most preferable to blend the microcapsules in an amount of 20 to 40% by weight and the adhesive in an amount of 60 to 80% by weight in terms of color realization and adhesive strength. If the adhesive is more blended than this range, there is no abnormality in the adhesive strength, but the ratio of the microcapsules is relatively low, which makes it difficult to apply the low sensitivity in the color implementation. On the contrary, when the adhesive is less than this range, the adhesive strength of the outermost layer and the barrier layer is low, so that the delamination phenomenon occurs, especially in a high temperature environment, and thus the moisture and gas barrier properties are deteriorated. do. The blending range applies to both aqueous type or oil type thermochromic inks.

As described with reference to FIG. 5, in the present invention, an aqueous type or an oil type ink layer 25 may be further formed in addition to the thermochromic ink layer 20.

Next, the barrier layer 3 is explained in full detail. The barrier layer 30 is a layer for blocking the ingress of moisture, gas, oxygen, etc. into the battery, and is made of a film deposited with a metal such as soft aluminum or nickel, or an inorganic compound such as silicon oxide or alumina. Although it is possible to use the soft aluminum foil, it is preferable because the tensile strength and elongation are high.

In addition, the aluminum foil preferably contains iron. In the case of containing iron, aluminum has good insulation properties, and pinholes are less likely to occur due to bending as a lamination agent, and in particular, when forming an embossed exterior Can also be easily formed. At this time, when the iron content is less than 0.6% by weight, there is no effect of preventing the occurrence of pinholes, improving the embossing formability, and when the iron content is higher than 2.0% by weight, the flexibility as aluminum is impaired, and the encapsulant as the laminating agent. In molding, the workability becomes poor. In addition, the aluminum preferably contains silicon, wherein when the silicon content is excessively increased to more than 0.9% by weight, the magnetic properties are improved, but the workability that can be formed into an encapsulation becomes worse, and is less than 0.05% by weight. If the content is reduced, the strength of the product is weakened and the elongation rate is lowered, resulting in poor processability to form a bag.

Therefore, the aluminum foil contains silicon (Si) and iron (Fe), but in particular, from the viewpoint of formability and workability, the silicon content is preferably 0.05 to 0.9 wt%, and preferably the iron content is 0.6 to 2.0 wt%. .

On the other hand, it is preferable that the aluminum is subjected to a non-chromate treatment for foil corrosion protection and adhesive strength improvement. The non-chromate treatment is to form an acid resistant film with at least one compound selected from the group consisting of organic and inorganic and organic compounds such as titanium resin, zirconium and phosphate. At this time, the non-chromate treatment is particularly preferable because treatment on both sides of the aluminum foil can further increase salt resistance.

Next, the sealant layer 40 which is an innermost layer is explained in full detail. The sealant layer 40 is preferably formed in 5 to 120㎛. An adhesive resin layer and a melt extrusion resin layer may be formed between the barrier layer 3 and the sealant layer 40. In particular, it is preferable to form an adhesive resin layer (or melt extruding resin layer) between the barrier layer 3 and the sealant layer 40 and to use a polyolefin (modified polypropylene) film or a deposition sealant layer as the sealant layer.

The formation structure of the said adhesive resin layer, a melt extrusion resin layer, and a sealant layer is demonstrated. The adhesive resin layer is formed by coating the barrier layer 30 with an adhesive resin that is easily adhered to aluminum to facilitate adhesion to a metal, preferably aluminum. In the case of a battery requiring heat resistance, a polypropylene resin is generally used as a sealant layer 40 material, and since it is not directly attached to aluminum, the adhesiveness that facilitates adhesion with aluminum is facilitated at this time. Coating the resin. The adhesive resin is used by dissolving at least one selected from the group consisting of modified polyethylene, modified polypropylene, modified acrylic resin and the like in a solvent.

A melt extrusion resin layer is formed between the adhesive resin layer and the sealant layer. The melt extrusion resin layer serves to laminate the upper and lower layers by providing an adhesive force by coating the film by melt extrusion coating. The melt extrusion resin layer is formed by melt extruding a polypropylene resin or polyethylene resin and coating a polypropylene resin or polyethylene resin film on the adhesive resin layer and laminating with a sealant layer.

When the melt extrusion coating, ozone is radiated using an ozone generator, which is an additional machine that emits ozone, to peroxidize the surface of the melt extrusion coating resin to improve adhesion and at the same time form an ozone film to improve the barrier property and adhesive water. It is possible to improve adhesion and sealing properties between the ground layer and the melt extrusion resin layer and the heat sealing layer.

When ozone is emitted to the resin extruded during the melt extrusion coating, the adhesive force is further improved. The ozone generator uses an existing known ozone generator. For example, the air in the air is compressed using an air compressor to separate nitrogen and oxygen from an oxygen generator, using only pure oxygen, and producing a high concentration of ozone using a plasma silent discharge system using high frequency and high voltage. The ozonated air is injected into the resin discharge port through the air nozzle to enhance the film adhesion strength by strongly oxidizing the resin film. The coating thickness of the melt extrusion resin layer is 10 to 80 ㎛, preferably 10 to 40 ㎛.

The said sealant layer uses the resin layer which can be sealed by heat. In the case of the molding type, the slipperiness and heat sealing strength characteristics of the mold surface in the molding machine during molding, and the crack, whitening, pinhole, etc. of the heat sealing layer due to the molding conditions during molding should be prevented. A plastic film formed by adding at least one selected from the group consisting of ethylene, butadiene, ethylene propylene rubber, etc. to at least one selected from the group consisting of polypropylene, ethylene copolymer, propylene copolymer and the like is preferably used. Modified polypropylene film is used.

The structure which forms an adhesive resin layer (or melt extrusion resin layer) and a vapor deposition sealant layer is demonstrated.

The deposition sealant layer was deposited on SiO ₂ , Al ₂ O ₃ on a monolayer or multilayer laminate film of polyolefin. By depositing any one of an oxide such as an oxide or a metal of any one of Cu, Fe, Sn, Zn, Ag, or Al, it not only provides high barrier property, but also prevents delamination with the barrier layer, and particularly provides excellent electrolyte resistance. It is to prevent the surface corrosion of aluminum by hydrogen fluoride generated by the reaction of electrolyte and water.

That is, the SiO ₂ , Al ₂ O ₃ in the sealant layer By directly depositing any one of an oxide such as an oxide or a metal of any one of Cu, Fe, Sn, Zn, Ag, or Al, high barrier properties can be obtained without forming an additional barrier layer, and excellent electrolyte solution Because of its properties, it is possible to prevent the penetration of the electrolyte. It is also more effective in preventing delamination (layer separation) between the barrier layer and the sealant layer due to the penetration of the electrolyte. In addition, the deposition of the oxide or metal directly on the sealant layer is more advantageous in terms of manufacturing process efficiency and manufacturing cost reduction. Furthermore, depositing directly on the sealant layer as described above has the advantage of enabling uniform distribution of the oxide or metal in the sealant layer and very easy control of the distribution.

The deposition is performed by physical vapor deposition, chemical vapor deposition, resistive heating deposition, plasma deposition, ion plating or sputtering, and the deposition thickness is preferably 200 ~ 500Å, if less than 200Å, the deposition uniformity is not good, 500 좋지 If exceeded, moldability decreases and cracks are caused.

On the other hand, as the polyolefin film, a polyolefin film formed of three layers is particularly preferable. That is, when the polyolefin film on which the oxide or the metal is deposited is formed of three layers, penetration of the electrolyte can be effectively prevented. The polyolefin film may be formed into four or more layers in excess of three layers, but a polyolefin film formed of three layers is most preferred in terms of process efficiency and economics.

More preferably, two adjacent polyolefins among the polyolefin films formed of the above three layers are polyolefins having different crystallinities.

That is, since the polyolefin film is not 100% gas barrier property, the electrolyte is permeable and the adhesion strength between the barrier layer and the sealant layer is reduced. To solve this, a layer is formed of polyolefins having different crystallinities. Even if the electrolyte permeates the first layer, the permeability decreases while contacting the second layer made of a polyolefin component having a different degree of crystallinity from the first layer, while permeating while contacting a third layer made of a polyolefin having a different degree of crystallinity from the second layer. The possibility can be further blocked. For example, when the film formed of the three layers of the polyolefin is PP / PE / PP, when the film formed of the three layers of PP / PP / PP is different from the film formed of the three layers of PP / PP, PE having different crystallinity is located in the second layer. It becomes more difficult itself and even if it is permeable, there is an advantage that can dramatically reduce the permeation time.

The adhesive resin layer is for laminating the barrier layer and the sealant layer. Of course, in this case, instead of the general adhesive resin layer, a melt-extruded resin layer formed by melt-extrusion coating of (modified) polypropylene or (modified) polyethylene resin may be used to provide adhesion. Here, it is preferable that the coating thickness of the said melt extrusion resin layer is 10-80 micrometers, and it is more preferable that it is 10-40 micrometers. When the molten extruded resin is coated, the surface of the molten extruded resin coated by ozone may be additionally oxidized to improve adhesion and at the same time to form an ozone film to improve barrier properties and sealability.

However, in the case of forming the deposition sealant layer, forming the melt-extruded resin layer has a disadvantage in that workability is lowered and manufacturing costs are expensive. Therefore, it is particularly preferable to form an adhesive resin layer using a general urethane adhesive instead of the melt-extruded resin. Better in terms of performance yield and unit cost

Hereinafter, the present invention will be described in more detail by explaining preferred examples and experimental examples of the present invention. However, the present invention is not limited to the following examples, and various forms of embodiments can be implemented within the scope of the appended claims, and the following examples are only ordinary in the art while making the disclosure of the present invention complete. It is intended to facilitate the implementation of the invention to those with knowledge.

[Experiment 1-Measurement of capsule resistance according to solvent (degree of encapsulation by solvent) and change over time (preservation)]

30 wt% water, 60 wt% ethanol, 10 wt% methanol (Example 1), toluene (Example 2), MEK (Comparative Example 1), EA (Comparative Example 2), isopropyl alcohol ( Comparative Example 3) 40 parts by weight of an acrylic resin in 50 parts by weight of each solvent of ethanol (Comparative Example 4) and methanol (Comparative Example 5), and thermochromic microcapsules (Chemyleon-T from Polychrome; solid content; red) Ten parts by weight were added and the resistance of the capsules to the solvent at 10 days, 20 days, and 30 days and their change over time were tested.

Specifically, in order to measure the resistance of the capsule according to the solvent and its change over time, the red microcapsules are broken down at each time and diluted to the solvent to confirm the degree of color drop, so that the color degradation does not appear and the resistance is good (" (Circle) "), the color degradation appeared in some parts, and the tolerance was moderate (" △ "), and the color degradation appeared overall and the tolerance was poor (" x ").

On the other hand, in order to measure the function of the temperature change, after the ink of each Example and Comparative Example 30 days after coating on a paper to prepare a sample. When the temperature is higher than 65 ℃, the degree of redness disappears with the naked eye, and when the temperature is lowered again, it is checked again to see the original red color. The temperature change function is good ("○"), and the temperature change function is medium. It was evaluated that it was a thing ("(DELTA)") and a thing with a bad temperature function ("x").

Table 1 shows each measurement result.

10 days 20 days 30 days Temperature change function Example 1 ○ ○ △ ○ Example 2 ○ ○ ○ ○ Comparative Example 1 △ △ × × Comparative Example 2 △ △ × × Comparative Example 3 ○ △ △ △ Comparative Example 4 ○ △ △ △ Comparative Example 5 ○ △ △ △

As can be seen from the above, Toluene (Example 2) was the most excellent resistance of the capsule to the solvent, MEK (Comparative Example 1), EA (Comparative Example 2) was greatly reduced the resistance of the capsule to the solvent , The ability to change temperature completely disappeared. On the other hand, isopropyl alcohol (Comparative Example 3), ethanol (Comparative Example 4), methanol (Comparative Example 5) were similar in the resistance of the capsule to the solvent, but the capsule resistance to the solvent over time was inferior. In the case of the solvent of Example 1, the capsule resistance to the solvent was excellent, and its change over time was good enough to be equivalent to toluene (Example 2).

Experiment 2: Measurement of Color Reproducibility and Distribution by Mixing Ratio

Biaxially stretched polyester film containing 100 mol parts of terephthalic acid as an acid component with respect to 130 mol parts of 1, 3- propane diols as a glycol component / Thermochromic ink layer / Urethane adhesive layer / Barrier layer (Al) / Polypropylene melt extrusion resin layer The cell pouch was composed of a sealant layer in which Al ₂ O ₃ was deposited on a polyolefin film formed of three layers.

In the thermochromic ink layer composed of a solvent, an acrylic resin, and a thermochromic microcapsule, color reproducibility and distribution change were measured while adjusting the respective contents of the thermochromic microcapsules (Chameleon-T of Polychrome).

모드로 측정하였다. 오차 범위가 3을 초과한 경우 색 재현성이 떨어진다고 보고 이를 "×"로 표현하였고, 그렇지 않은 경우 색 재현성이 양호한 것으로 보고 이를 "○"과 같이 표현하였다. 캡슐 분포는 SEM으로 분포 및 상태를 파악하였다. SEM 측정 결과 10,000개/mm² 이상이 경우 "○"로 표시하고, 1,000 내지 10,000개/mm² 인 경우 "△"로 표시하고, 1,000개/mm² 이하인 경우 "×"로 표시하였다.The color standard is judged using the PAN paper, which is the color standard.

Measured in mode. When the error range exceeded 3, it was reported that the color reproducibility was inferior, and this was expressed as "x". Capsule distribution was analyzed by SEM and distribution. As a result of SEM measurement, when it is 10,000 pieces / mm <^2> or more, it shows as "(circle)", and when it is 1,000-10,000 pieces / mm <^2> , it shows as "(triangle | delta)" and when it was 1,000 pieces / mm <^2> or less, it represented by "x".

Table 2 shows the measurement results.

Thermochromic Microcapsule Content Color reproduction Distribution 5 parts by weight × × 9 parts by weight × △ 10 to 40 parts by weight ○ ○

As can be seen from the above, when the thermochromic microcapsules were contained in less than 10 parts by weight, such as 5 parts by weight and 9 parts by weight of the total ink composition, the color reproducibility was poor and the distribution also decreased. On the other hand, in the range of 10 to 40 parts by weight, both in color reproducibility and distribution were good.

[Experiment 3: Measurement of Color Reproducibility and Adhesive Strength According to Mixing Ratio of Thermochromic Ink and Adhesive]

Melt-extrusion of biaxially stretched polyester film containing 100 mol parts of terephthalic acid as acid component / thermochromic ink and urethane adhesive mixed with 130 mol parts of 1,3-propane diol as glycol component / barrier layer (Al) / polypropylene melt extrusion The cell pouch was constituted by a sealant layer in which Al ₂ O ₃ was deposited on a polyolefin film formed of a resin layer / 3 layers.

The thermochromic ink composition is 30 parts by weight of water, 60 parts by weight of ethanol, 50 parts by weight of a solvent consisting of 10% by weight of methanol, 40 parts by weight of an acrylic resin, 10 parts by weight of thermochromic microcapsules (Chemyleon-T of Polychrome; solid content) Configured.

Color reproducibility and adhesive strength were measured while changing the thermochromic ink composition and urethane adhesive as shown in the following table.

Color reproducibility test was carried out as in Experiment 2.

Adhesive strength is to evaluate the delamination properties, the delamination strength was measured at the time of peeling the Al layer and the sealant layer of the pouch specimen. Specifically, the pouch specimen was cut to a constant size (width 15mm × length 150mm), and the outermost layer and the Al layer of the prepared specimen were peeled off. The peeled specimen was mounted on a tensile strength tester (SHIMADZU AGS-100D), and the test method measured physical properties according to the JIS K 7127 test standard and determined the measured value. The thing less than 500 gf was represented by "X", and the thing less than 500 gf was represented by "(circle).

Table 3 shows the measurement results.

Thermochromic ink composition Urethane adhesive Color reproduction Adhesive strength Compounding cost 1-20 wt% 80-99% by weight × ○ 20-40 wt% 60 to 80% by weight ○ ○ 40-90 wt% 10 to 60% by weight ○ ×

As can be seen from the above, when the thermochromic ink composition is 1 to 20% by weight and the urethane adhesive is 80 to 99% by weight, the adhesive strength is good but the color reproducibility is low and the thermochromic ink composition is 40 to 90% by weight. In the case of the urethane adhesive of 10 to 60% by weight, the color reproducibility was good, but the adhesive strength was low. On the other hand, when the thermochromic ink composition is 20 to 40% by weight and the urethane adhesive is 60 to 80% by weight, both color reproducibility and adhesive strength were good.

According to the cell pouch of the lithium secondary battery or the portable storage battery of the present invention, the cell pouch itself can express the abnormal increase in the internal temperature of the cell due to an overcharge or an internal short circuit caused by an abnormal reaction inside the cell. And reliability can be ensured.

In addition, the cell pouch of the present invention is short and light in manufacturing time, free in shape, and excellent in heat resistance, electrical insulation, moisture resistance and gas barrier properties, stability, chemical resistance, heat seal strength, and moldability.

Although the present invention has been described in connection with the above-mentioned preferred embodiments, it is possible to make various modifications or variations without departing from the spirit and scope of the invention. Accordingly, the appended claims will cover such modifications and variations as fall within the spirit of the invention.

Claims (12)

In the cell pouch, A cell pouch comprising a thermochromic ink layer containing a thermochromic dye which discolors with a change in temperature in a laminated configuration of a cell pouch. The method of claim 1, The thermochromic ink includes a thermochromic microcapsule, wherein the thermochromic microcapsule has a particle diameter greater than 0 µm and 3 µm or less. The method of claim 2, The thermochromic microcapsules having a particle diameter of greater than 0 µm and less than or equal to 3 µm are contained in 50 wt% or more and 100 wt% or less based on the total microcapsules. The method of claim 1, wherein the thermochromic inks 10 to 40 parts by weight of thermochromic microcapsules; 20 to 40 parts by weight of acrylic or urethane resin; And 30 to 50 parts by weight of the solvent; cell pouch comprising a. The method of claim 4, wherein The thermochromic ink may include 1 to 5 parts by weight of at least one additive selected from the group consisting of waxes, colorants, antifoams, slip agents, pH adjusters, and heat reinforcing agents; 10 to 40 parts by weight of thermochromic microcapsules; 20 to 40 parts by weight of acrylic or urethane resin; And 30 to 50 parts by weight of the solvent; a cell pouch further comprising a thermochromic ink. The method of claim 4, wherein the solvent, 25 to 60% by weight of water, 20 to 60% by weight of ethanol, Cell pouch, characterized in that composed of 5 to 20% by weight of any one or both of methanol or isopropyl alcohol. The method of claim 4, wherein The solvent is an organic solvent, cell pouch characterized in that toluene is contained in 65% by weight or more and 100% by weight or less. The method of claim 4, wherein The thermochromic ink layer, 20 to 40% by weight of the thermochromic ink; And a mixed layer of a thermochromic ink and an adhesive composed of 60 to 80 wt% of an adhesive. In the manufacturing method of the cell pouch, A method of manufacturing a cell pouch, comprising a thermo-paging ink layer containing a thermochromic dye that changes color with a change in temperature in a laminated configuration of the cell pouch. The method of claim 9, The thermochromic ink layer comprises a thermochromic microcapsule containing a thermochromic dye. The method of claim 2, The outer wall of the thermochromic microcapsule is a cell pouch, characterized in that formed by one or more selected from the group consisting of melamine resin, formaldehyde, yeast, starch and dextrin. In the cell pouch, A cell pouch comprising a thermochromic ink layer containing a thermochromic microcapsules that change color with a change in temperature in a laminated structure of a cell pouch.

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