KR20080089270A - Packaging material for flat type eletrochemical cell - Google Patents

Abstract

A packaging material for a flat type electrochemical cell is provided to prevent cracks at a bent portion even in bending the inner edge of a seal part around an exterior body by keeping uniform flexibility and durability of a heat-adhesive resin layer even after the heat-adhesive resin layer is crystallized by a heat seal. A packaging material for a flat type electrochemical cell is composed of a base layer(6), a metal thin layer(7) having a chemically treated layer(7a) on at least one surface, an acid modified polyolefin layer(9), and a heat-adhesive resin layer(8), which are laminated in order. The acid modified polyolefin layer is a resin layer made of acid modified polyolefin resin. The heat-adhesive resin layer has a resin layer made of propylene resin. Propylene elastomer resin is mixed with acid modified polyolefin resin or polyolefin resin. Propylene elastomer resin is copolymer consisting of a constituent unit derived from propylene and a constituent unit provided with 2~20 carbons and derived from alpha-olefin except for propylene. A constituent unit derived from propylene is included over 50mol.% to the sum of a constituent unit derived from propylene and a constituent unit derived from alpha-olefin of 100mol.%. Shore hardness of the packaging material is 65~90. A melting point is 130~170°C. Density is 860~875kg/m^3. Glass transition temperature measured by a DSC(Differential Scanning Calorimeter) is -25~-35°C.

Description

PACKAGING MATERIAL FOR FLAT TYPE ELETROCHEMICAL CELL

The present invention relates to a packaging material for flat electrochemical cells exhibiting stable sealing properties, insulating properties and formability.

A lithium ion battery is also called a lithium secondary battery, and has an electrolyte of a liquid form, a gel form, or a polymer polymer form, and includes a cathode and a cathode active material comprising a polymer polymer. In the lithium ion battery, during charging, lithium atoms (Li) in the lithium transition metal oxide serving as the positive electrode active material become lithium ions (Li ⁺ ), are interposed between the carbon layers of the negative electrode (intercalation) and discharged. Is a battery in which lithium ions (Li ⁺ ) are separated from the carbon layer (deintercalation), move to the positive electrode, and become charges and discharge reactions as they become original lithium compounds. It has an excellent characteristic that there is no so-called memory effect that the output voltage is higher, the energy density is high, and the apparent discharge capacity is reduced by repeating the shallow discharge and recharging.

In addition, the structure of a lithium ion battery consists of a positive electrode current collector material / positive electrode active material layer / electrolyte layer / negative electrode active material layer / negative electrode current collector material, and an exterior body which wraps these, and presses a conventional metal as a packaging material which forms an exterior body. Metal pipes processed and containerized into a cylindrical or rectangular parallelepiped shape have been used.

However, since the outer wall of the container is hard, the metal tube has a limited shape, and since there is no degree of freedom in shape since it is necessary to design the hard side in accordance with the battery, recently, a multilayer film is used as a packaging material instead of the metal tube. There is a tendency to use it. This packaging material consists of at least a base material layer, a metal foil, and a heat-adhesive resin layer, forms the packaging material into a bag shape, forms the pouch type which accommodates a battery main body, or press-processes the packaging material, and forms a recessed part. The embossed type exterior body which accommodates a battery main body is formed in the part. For example, in JP-A-2005-56729 as a battery packaging material, an acid-modified poly with a thickness of 1 to 5 µm for bonding a non-stretched polypropylene layer having a thickness of more than 10 µm to 60 µm or less, a metal foil and a heat adhesive resin layer. A packaging material has been proposed in which a propylene layer and a first chemical conversion film layer having a coating amount of 5 to 30 mg / m 2 are sequentially laminated with a thin aluminum layer having a thickness of 10 to 100 μm and a layer made of a synthetic resin.

Fig. 12A is a perspective view of a conventional pouch type lithium ion battery 1, and Fig. 12B is a schematic perspective view showing an exploded view of a conventional pouch type lithium ion battery. As shown in FIG. 12A and FIG. 12B, in the pouch type lithium ion battery 1, the lithium ion battery main body 2 is hermetically housed in a bag 10 having a bag shape. 13A is a perspective view of a conventional embossed lithium ion battery 1, and FIG. 13B is a schematic perspective view showing a conventional embossed lithium ion battery in an exploded manner. As shown in FIGS. 13A and 13B, the embossed lithium ion battery 1 uses a lithium ion battery main body 2 using an exterior body 10 formed of a tray 10t and a sheet 10s on which an embossed portion is formed. ) Is housed in a sealed manner.

In either type, when the lithium ion battery main body 2 is sealed with the outer case 10, the metal terminal 4 connected to each of the positive electrode and the negative electrode of the lithium ion battery main body 2 is the outer case 10. ) The sealing property is secured by protruding to the outside and inserting and heat-sealing the metal terminal 4 between the exterior bodies 10. In addition, the lithium ion battery main body 2 contains the positive electrode which consists of a positive electrode active material and a positive electrode collector, the negative electrode which consists of a negative electrode active material and a negative electrode collector, and the electrolyte (not shown in figure) filled between a positive electrode and a negative electrode. It is composed of a cell (capacitor) and a metal terminal 4 which is connected to a positive electrode and a negative electrode in the cell and whose tip is protruded outside of the exterior body 10.

In addition, when the lithium ion battery 1 is actually used, the exterior body 10 alone is weak in impact resistance, and small damage may cause cracking, so the lithium ion battery 1 is stored in a plastic case. It is often used.

FIG. 14A is a schematic perspective view showing a conventional lithium ion battery 1, and FIG. 14B is a schematic perspective view showing a conventional lithium ion battery 1 housed in a plastic case 13 indicated by a dotted line.

Here, in order to reduce the size of the lithium ion battery 1, the plastic case is formed by bending (that is, bending and bending) the seal portion 10b around the exterior of the lithium ion battery 1. It is necessary to store it in (13). FIG. 14C is a cross-sectional view of the lithium ion battery 1 housed in the plastic case 13 as viewed in the arrow x direction of FIG. 14B.

However, in the bent portion 10c, which is a folding mark of the internal magnetic field of the peripheral seal portion 10b, the heat-adhesive resin layer, which is the innermost layer of the outer package 10, is melted once during heat sealing, and then crystallized thereafter. Because of this, cracking is liable to occur during bending. In addition, when this cracking occurs, since the electrolyte inside the exterior body 10 comes into contact with the metal foil constituting the exterior body 10 and the metal foil is energized, the output of the lithium ion battery is remarkably lowered, and thus the battery functions. The loss is a problem.

Moreover, also in the embossing formation process of the exterior body 10 by press work, when the metal excellent in elongation like aluminum is used for the metal foil which comprises the exterior body 10, the innermost part of the exterior body 10 is carried out. The elongation of the heat-adhesive resin layer of the layer does not follow the stretching of aluminum, and the aluminum and the heat-adhesive resin layer may peel off, or cracks may occur in the heat-adhesive resin layer. In addition, the battery packaging material shown in JP-A-2005-56729 did not sufficiently solve the said problem.

In addition to storing the lithium ion battery main body 2 in the exterior body 10, the same problem occurs when the capacitor and the electric double layer capacitor are housed and sealed sealed.

Therefore, in view of the above problems, the present invention provides a flexible, heat resistant, sealing seal in a packaging material for flat electrochemical cells of an exterior body that seals and houses flat electrochemical cells such as a lithium ion battery body, a capacitor, and an electric double layer capacitor. An object of the present invention is to provide a packaging material for flat electrochemical cells having excellent properties, insulation and moldability.

In order to achieve the above object, a first configuration of the present invention is a flat type electric machine in which a base material layer, a metal thin layer having a chemical conversion treatment layer on at least one side thereof, an acid-modified polyolefin layer, and a heat-adhesive resin layer are sequentially laminated at least. In the packaging material for chemical cells, the acid-modified polyolefin layer is a resin layer composed of an acid-modified polyolefin resin, and the heat-adhesive resin layer has a resin layer composed of a propylene resin, and at least the acid-modified polyolefin resin A propylene-based elastomer resin is mixed with one of the resins or the propylene-based resin, and the propylene-based elastomer resin is a copolymer composed of propylene-derived structural units and 2 to 20 carbon atoms and structural units derived from α-olefins except propylene. The total of the structural unit derived from the said propylene, and the structural unit derived from the said (alpha) -olefin is 100 mol% A constituent unit of the propylene-derived when a not less than 50 mol%,

(a) Shore A hardness (ASTM D2240) is 65 to 90,

(b) the melting point is from 130 to 170 ° C;

(c) a density (ASTM D1505) is 860 to 875 kg / m 3;

(d) It is a packaging material for flat electrochemical cells characterized by the glass transition temperature by DSC measurement -25 degreeC--35 degreeC.

According to a second aspect of the present invention, in the above-mentioned flat electrochemical cell packaging material, the propylene-based elastomer resin is mixed in an amount of 3% by weight or more and 30% by weight or less with respect to the propylene-based resin.

According to a third aspect of the present invention, in the packaging material for a flat electrochemical cell, the metal thin layer is an aluminum foil having a thickness of 80 µm or more and 120 µm or less.

According to the 1st structure of this invention, acid-modified polyolefin layer and / or heat-adhesive resin layer which comprise the packaging material for flat electrochemical cells have acid-modified by having the resin layer which consists of resin which mixed the propylene-type elastomer resin. The flexibility, heat resistance and impact resistance of the polyolefin layer and / or the heat adhesive resin layer are greatly improved. As a result, when the packaging material for flat electrochemical cells is used as an exterior body of a lithium ion battery, since the heat-adhesive resin layer maintains a constant flexibility and durability even after crystallization by heat seal, when storing in a plastic case Even if the magnetic field inside the seal portion around the exterior body is bent, the occurrence of cracks in the bent portion can be prevented. Therefore, the electrolyte in the exterior can be prevented from coming into contact with the thin metal layer from the cracked portion, and the insulation of the exterior can be ensured.

In addition, since the acid-modified polyolefin layer and / or the heat-adhesive resin layer have a certain flexibility and durability, when the outer body is pressed and embossed, the metal thin layer and the heat-adhesive resin layer are peeled off or cracked. It can be prevented from occurring.

According to the second aspect of the present invention, the acid-modified polyolefin layer after the heat seal, in the above-mentioned flat electrochemical cell packaging material, by adjusting the mixing amount of the propylene elastomer resin to the propylene resin to 3% by weight or more and 30% by weight or less. The physical property of a heat-adhesive resin layer can be made more stable, and it can improve.

According to the 3rd structure of this invention, when an exterior body has aluminum foil which is 80 micrometers-120 micrometers in thickness, the impact resistance as an exterior body and the resistance to being stuck by a sharp thing (henceforth abbreviation "sticking resistance") improve.

In general, when the thickness of the aluminum foil is large, distortion and fine wrinkles tend to occur between the aluminum foil and the heat-adhesive resin layer when pressing the flat electrochemical cell packaging material, but the acid-modified polyolefin layer and / or These problems can be solved by configuring the heat-adhesive resin layer with a propylene resin layer mixed with a propylene-based elastomer resin having excellent durability and flexibility.

The present invention is an electrochemical cell packaging material excellent in flexibility, heat resistance, sealing sealability, moldability, low temperature sealing property, and insulation property. The packaging material will be described in more detail with reference to the drawings. 12A, 12B, 13A, 13B, 14A, 14B, and 14C of the conventional example are denoted by the same reference numerals and description thereof will be omitted.

First, the material etc. which comprise each layer of the electrochemical cell packaging material of this invention are demonstrated with reference to FIG. As shown in FIG. 1, the packaging material according to the present invention which can be used for the exterior body 10 includes a base material layer 6 at the outermost layer, a heat-adhesive resin layer 8 at the innermost layer, and a thin metal layer therebetween. (7) is arrange | positioned, The heat-adhesive resin layer 8 and the metal thin layer 7 are adhere | attached through the acid-modified polyolefin layer 9. At this time, by providing the chemical conversion treatment layer 7a on the surface of the metal thin layer 7, the interlayer adhesive strength between the base layer 6 and the heat-adhesive resin layer 8 and the metal thin layer 7 is more stable. Moreover, the protective layer 11 is formed in the surface of the base material layer 6. In addition, the packaging material for an electrochemical cell of the present invention includes a base layer 6, a metal thin layer 7 having a chemical conversion treatment layer 7a, an acid-modified polyolefin layer 9, and a heat-adhesive resin layer 8. What is necessary is just to laminate | stack in order, and can also comprise it through interposing different types of layers between each layer.

Here, as a lamination method of the thin metal layer 7 and the heat-adhesive resin layer 8 in the packaging material which concerns on this invention, it can divide roughly by the dry lamination method and the thermal (thermal) lamination method. The dry lamination method is excellent in productivity because it is laminated using an adhesive, but has high water permeability in the cross section of the adhesive layer, and moisture penetrating in the cross section penetrates the inner layer and reacts with the electrolyte to generate hydrofluoric acid. This hydrofluoric acid peels between the thin metal layer 7 and the heat-adhesive resin layer 8 with time, and causes liquid leakage.

In addition, in the thermal lamination method, a method of laminating a coextruded film made of the acid-modified polyolefin layer 9 and the heat-adhesive resin layer 8 to the metal thin layer 7 by the thermal lamination method, and the melted acid-modified polyolefin There is a sandwich lamination method in which the layer 9 is inserted between the thin metal layer 7 and the heat-adhesive resin layer 8 and laminated, and both methods have a resistance to contents in comparison with the dry lamination method. It is a lamination method with excellent durability.

Specifically, in the thermal lamination method, a metal thin layer such as aluminum having undergone chemical conversion treatment on the surface of the acid-modified polyolefin layer 9 of the coextruded film composed of the acid-modified polyolefin layer 9 and the heat-adhesive resin layer 8 ( The method of thermal lamination by bonding the chemical conversion treatment layer 7a of 7) is performed. The sandwich lamination method extrudes the acid-modified polyolefin layer 9 as an adhesive resin to the chemical conversion treatment layer 7a of the metal thin layer 7 and heats it. It is a method of adhering with the adhesive resin layer 8. Here, in the case of extrusion lamination of the acid-modified polyolefin layer 9, the resulting laminate is heated (post-heated) above the softening point of the acid-modified polyolefin, or in the extrusion processing of the acid-modified polyolefin, the surface of the aluminum is acidified. By heating (preheating) above the softening point of the modified olefin, the packaging material can be used as a package to enable a laminate having adhesive strength that can withstand the contents resistance and formability.

As this heating method, there are a method such as a hot roll contact type, a hot air type, a near or far infrared ray type, but any heating method may be used in the present invention, and as described above, the adhesive resin may be heated above the softening point temperature. If you can.

Next, each layer of the packaging material which comprises the exterior body 10 shown in FIG. 1 is demonstrated concretely. The heat-adhesive resin layer 8 of the innermost layer is thermally bonded by inserting the metal terminal 4 (see FIG. 12) of the lithium battery main body 2 in a protruding state to the outside. At this time, the propylene constituting the heat-adhesive resin layer 8 depends on whether or not an adhesive film for sealing the metal terminal having metal adhesion is interposed between the heat-adhesive resin layer 8 and the metal terminal 4. The type of resin is different. When interposing the adhesive film for metal terminal sealing, a film made of a single substance or a mixture of propylene-based resin may be used, but when the adhesive film for metal terminal sealing is not interposed, an acid graft-modified with unsaturated carboxylic acid is used. It is necessary to use the film which consists of a modified olefin resin.

As the heat-adhesive resin layer 8, propylene-based resin (in the following description, propylene-based resin may be simply abbreviated as polypropylene) can be suitably used, but a single layer of linear low-density polyethylene and medium-density polyethylene Alternatively, a single layer or a film composed of a multilayer or a blend resin of linear low density polyethylene and medium density polyethylene may be used.

Moreover, polypropylene can be divided into various types, such as a random polypropylene, a homo polypropylene, and a block polypropylene, In the multilayer polypropylene film which consists of these types of polypropylene, the polypropylene film which mixed the propylene-type elastomer resin By including in the lamination, physical properties such as durability, flexibility, and whitening resistance of the heat-adhesive resin layer 8 can be increased.

The polypropylene mixed with the propylene-based elastomer resin does not take a structure in which the resin is dispersed in an island-like shape with the amorphous portion as the sea and the crystal portion as the island like the ethylene-propylene random copolymer. "Isles", which are spiral crystal portions, are connected to each other to take a network (i.e., net-like) structure to cover the entire amorphous portion. With this "net" structure, the polypropylene mixed with the propylene-based elastomer resin has excellent seal strength, durability, heat resistance, and flexibility.

Thereby, the shaping | molding limit of the packaging material containing the polypropylene which mixed the propylene-type elastomer resin can be raised, and the metal thin layer 7 and the heat-adhesive resin layer 8 peel or heat-bond by press molding. Cracking can be prevented from occurring in the resin layer 8.

Since the crystal part of the polypropylene which mixed the propylene-type elastomer resin is a "net" structure, it is considered that a "net" structure remains and solidifies uniformly even when it melts and solidifies once at the time of heat sealing.

For this reason, when the lithium ion battery 1 shown in FIG. 14B is accommodated in the plastic case 13, the crack generation can be prevented also in the process of bending the seal inner edge of the outer periphery 10b. Since the electrolyte inside the exterior body does not come into contact with the thin metal layer 7 from the cracked portion, the insulation of the exterior body 10 can be ensured.

In general, when the degree of crystallinity is increased to increase the heat resistance, the flexibility decreases. However, in the polypropylene in which the present propylene-based elastomer resin is mixed, the amorphous part is incorporated at the nano level inside the crystal part, and the amorphous part that surrounds the periphery is used. Since it takes the structure of connecting, even if it raises heat resistance, flexibility does not fall.

Thereby, when heat-sealing the polypropylene which mixed the propylene-type elastomer resin, sufficient sheet strength can be obtained even if it heat-seals at low temperature from the melting point of the polypropylene which does not mix the propylene-type elastomer resin. For this reason, the sealing time can be shortened, the heat sealing process can be simplified, and the production efficiency of a lithium ion battery can be improved.

In addition, when the propylene-based elastomer resin is mixed with 3% by weight or more and 30% by weight or less with respect to polypropylene, the physical properties of the polypropylene layer can be most improved.

Here, the propylene-type elastomer resin which concerns on this invention is a copolymer which consists of a structural unit derived from propylene, and a structural unit derived from C2-C20 alpha-olefin (except propylene), and the structural unit derived from propylene is 50 It contains mol% or more (the sum total of the structural unit derived from propylene and the structural unit derived from C2-C20 alpha-olefin is 100 mol%),

(a) Shore A hardness (ASTM D2240) is 65 to 90,

(b) the melting point is from 130 to 170 ° C;

(c) a density (ASTM D1505) is 860 to 875 kg / m 3;

(d) The glass transition temperature by DSC measurement satisfy | fills the physical property which is -25 degreeC--35 degreeC.

Specifically, the α-olefin having 2 to 20 carbon atoms (excluding propylene) constituting the propylene-based elastomer resin according to the present invention includes ethylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, etc. are mentioned.

In addition, the propylene-based elastomer resin according to the present invention is a copolymer made of a propylene-derived structural unit and a structural unit derived from a C 2-20 alpha -olefin (excluding propylene). It is more preferable when it is a copolymer which consists of a structural unit derived from ethylene, and a structural unit derived from C4-C10 alpha-olefin.

Moreover, when the sum total of the structural unit derived from propylene and the structural unit derived from propylene and the structural unit derived from C2-C20 alpha olefin (excluding propylene) is 100 mol%, 50 mol% or more 99 It is mole% or less, Preferably they are 60 mol% or more and 99 mol% or less.

Moreover, (a) Shore A hardness of the propylene-type elastomer resin which concerns on this invention is 65-90, Preferably it is 65-85, More preferably, it is the range of 72-85. In addition, the measuring method of Shore A hardness is mentioned later. Moreover, (b) melting | fusing point is the range of 130-170 degreeC, Preferably it is 130-150 degreeC. In addition, the measuring method of melting | fusing point is mentioned later. Moreover, (c) density is the range of 860-875 kg / m <3>, Preferably it is 860-872 kg / m <3>. In addition, the measuring method of density is mentioned later. Moreover, the glass transition temperature (Tg) measured by (d) DSC is the range of -25 degreeC--35 degreeC, Preferably it is -26 degreeC--33 degreeC. In addition, the measuring method of glass transition temperature (Tg) is mentioned later.

Moreover, it is preferable that the propylene-type elastomer resin which concerns on this invention satisfy | fills said (a), (b), (c) and (d), and satisfy | fills one of following (e) or (f), More preferably, both (e) and (f) are satisfied:

(e) Haze (internal haze) is less than 15%, preferably less than 10%.

(f) Melt flow rate (MFR (melt flow rate), measured at 230 degreeC and a load of 2.16 kg based on ASTMD1238) is 3-15 g / 10min, Preferably it is the range of 5-10 g / 10min.

Next, the measuring method of the physical property shown by said (a)-(f) is demonstrated one by one. The Shore A hardness of (a) was left to stand at 23 ° C. for 72 hours after pressing the 2 mmt press sheet obtained by molding under the following press molding conditions. The scale was taken and read (according to ASTM D2240).

Press molding conditions: temperature 190 degreeC, heating, pressurization time 7 minutes, It cools in a 15 degreeC cooler.

The melting point (Tm) of (b) is about 10 mg of the sample filled in an aluminum pan, (i) 100 ° C./min to 200 ° C. and maintained at 200 ° C. for 5 minutes, and (ii) at 10 ° C./min. The temperature of the endothermic peak observed in (iii) was measured when the temperature was lowered to −150 ° C. and then (iii) the temperature was raised to 10 ° C. from 10 ° C./min.

In addition, the density of (c) is measured by the method based on ASTMD1505, after leaving a 2 mm in press sheet obtained at the same press molding conditions as the said Shore A hardness measurement sample for 72 hours at 23 degreeC.

Moreover, the glass transition temperature (Tg) of (d) fills about 10 mg of samples with a dedicated aluminum pan, (i) It raises from 30 degreeC to 200 degreeC at 200 degreeC / min, hold | maintains at 200 degreeC for 5 minutes, (ii) The temperature is lowered from 200 ° C to -100 ° C at 10 ° C / min, held at -100 ° C for 5 minutes, and then (iii) at 10 ° C / min. It was calculated | required by the DSC curve in this case (iii). In the examples, DSCRDC220 manufactured by Seiko Instruments Co., Ltd. was used.

In addition, the haze (internal haze) of (e) was made by Nippon Denshoku Kogyo Co., Ltd. after leaving a 2 mmt press sheet obtained at the same press molding conditions as the said Shore A hardness measurement sample at 23 degreeC for 72 hours. The amount of diffuse transmitted light by C light source and total amount of transmitted light by C light source was measured in a cyclohexanol solution using a digital turbidimeter (NDH-2000), and haze (internal haze) was measured by the following formula.

Haze (%) = 100 x (diffuse transmitted light amount) / (total transmitted light amount)

In addition, melt flow rate (MFR) of (f) is measured at 230 degreeC and 2.16 kg of loads based on ASTMD1238.

In addition, content of each structural unit is measured using ¹³ CNMR.

As described above, the propylene-based elastomer resin according to the present invention is not particularly limited as long as it satisfies the above physical properties. For example, a commercially available one may be used. As what is marketed, "Nothio (trademark)" made by Mitsui Chemicals Co., Ltd. is mentioned, for example, It is not limited to this.

In addition to the base layer 6, the metal thin layer 7, and the heat-adhesive resin layer 8, an intermediate layer made of a biaxially oriented film such as polyimide, polyethylene terephthalate, or the like may be thermally adhesive with the metal thin layer 7. You may provide between the resin layers 8. An intermediate | middle layer can prevent the short circuit by the strength improvement as the packaging material for electrochemical cells, stabilization of improvement of barrier property, and the contact of the tab and metal thin layer at the time of heat sealing of a lithium ion battery exterior body.

Further, by using a high melting point type having a melting point of 140 to 180 DEG C for the intermediate layer, for example, in the lithium ion battery 1 shown in Fig. 12A, the temperature inside the exterior body 10 due to overcharge or the like is caused. Also rises, the metal terminal 4 generates heat, and even when the metal terminal 4 insertion portion of the innermost layer of the exterior body 10 is melted, the intermediate layer is not melted, and the metal terminal 4 and the metal are not melted. The thin layer 7 can be prevented from contacting and shorting.

In addition, the heat-adhesive resin layer 8 may be formed by further processing the polypropylene layer melt-extruded on the innermost layer surface of the exterior body 10. By further processing the melt-extruded polypropylene layer, the heat sealing temperature can be lowered while securing a predetermined seal strength. This is considered to be because the melt-extruded polypropylene layer has a lower melting point and higher fluidity than other polypropylene layers not melt-extruded constituting the heat-adhesive resin layer 8.

Usually, when heat-sealing a polypropylene layer, it is necessary to apply heat and pressure near melting | fusing point (about 190 degreeC) of a polypropylene layer to a seal part. However, by providing a melt-extruded polypropylene layer having a melting point of 120 to 150 캜 on the surface of the polypropylene layer, heat sealing can be performed at a lower temperature than the melting point of the unstretched polypropylene layer.

In addition, it can be seen that when a melt index of 5 g / 10 min or more and 30 g / 10 min or less is used for the melt-extruded polypropylene layer at this time, sufficient sealing strength can be ensured at the sealing temperature.

For example, as shown in FIGS. 12A and 12B, the lithium ion battery main body 2 is enclosed in the exterior body 10, and the metal terminal 4 of the battery main body is inserted in the state protruding outward and sealed. When sealing, since the fluidity of the melt-extruded polypropylene layer is high, the opening part of the exterior body 10 is sealed-sealed so that the whole insertion part of the metal terminal 4 may be covered. Therefore, the external water vapor which penetrates from the insertion part of the metal terminal 4 can be interrupted | blocked, and generation | occurrence | production of hydrofluoric acid by reaction of an electrolyte and water vapor can be suppressed.

Here, by using the resin in which the melt-extruded polypropylene layer is mixed with a propylene elastomer resin, the characteristics of the polypropylene layer in which the propylene elastomer resin is mixed while maintaining the properties of the melt-extruded polypropylene layer The heat-adhesive resin layer which has both can be comprised.

In addition, each of the above types of polypropylene, i.e., random polypropylene, homo polypropylene, block polypropylene, has three components of low crystalline ethylene-butene copolymer, low crystalline propylene-butene copolymer, ethylene, butene and propylene. You may add the antiblocking agent (made by AＢ), such as a terpolymer which consists of copolymers, a silica, a zeolite, and acrylic resin beads, a slip agent of a fatty acid amide system, etc.

In addition, the heat-adhesive resin layer 8 which concerns on this invention is multilayered by combining the single layer which consists of said each type of polypropylene, or the said polypropylene layer of each type timely.

Next, the base material layer 6 is demonstrated. The base material layer 6 generally consists of a stretched polyester or a nylon film, but at this time, as the polyester resin, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, copolymerized poly Ester, polycarbonate, etc. are mentioned. Examples of nylon include polyamide resins, that is, nylon 6, nylon 6,6, copolymers of nylon 6 and nylon 6,6, nylon 6,10, polymethylene adipamide (MXD6), and the like. .

In addition, the base material layer 6 can also laminate | stack a film of another material other than a polyester film or a nylon film, in order to improve pinhole resistance and the insulation at the time of using it as an exterior body of a battery. When laminate | stacking the base material layer 6, a base material layer contains at least 1 resin layer of 2 or more layers, and the thickness of each layer is 6 micrometers or more, Preferably it is 6-25 micrometers. As an example of laminating | stacking a base material layer, although not shown, the following 1) -7) are mentioned:

1) stretched polyethylene terephthalate / stretched nylon

2) stretched nylon / stretched polyethylene terephthalate

3) Fluorine-based resin / stretched polyethylene terephthalate (Fluorine-based resin is formed by drying after film or liquid coating)

4) Silicone resin / stretched polyethylene terephthalate (silicone resin is formed by drying after film or liquid coating)

5) Fluorine Resin / Stretched Polyethylene Terephthalate / Stretched Nylon

6) Silicone resin / stretched polyethylene terephthalate / stretch nylon

7) Acrylic resin / stretched nylon (Acrylic resin is cured by drying after film or liquid coating)

In addition, as shown in 3) to 7), the exterior of a lithium ion battery by mechanical aptitude of packaging materials (stability of conveyance in packaging machines and processing machines), surface protection (heat resistance, electrolyte resistance), and secondary processing In order to make the sieve 10 into the emboss type, in order to reduce the frictional resistance between the metal mold | die at the time of embossing, and the base material layer 6, or in order to protect the base material layer 6 when electrolyte solution adheres, a base material layer It is preferable to multilayer (6) and to provide the protective layer 11 (refer FIG. 1), such as a fluorine resin layer, an acrylic resin layer, a silicone resin layer, a polyester resin layer, and these blend water layers, on the surface of a base material layer. .

Moreover, the same effect can be acquired also when extending | stretching polybutylene terephthalate and polyethylene naphthalate are used instead of the said extending | stretching polyethylene terephthalate.

Here, the base material layer 6 is bonded by the metal thin layer 7 and the adhesive bond layer 12 using the dry lamination method.

Next, the metal thin layer 7 is demonstrated. The thin metal layer 7 is a layer for preventing the ingress of water vapor into the inside of the lithium ion battery from the outside, and stabilizes the pinhole of the thin metal layer and processing ability (pouching, embossing formability), and also pinhole resistance. In order to have a metal having a thickness of 15 µm or more, such as aluminum or nickel, or an inorganic compound, for example, a film in which silicon oxide or aluminum oxide is deposited, etc. may be mentioned. In many cases, aluminum foil having a thickness of 80 µm was used.

Here, the heat adhesive resin layer 8 which concerns on this invention is comprised from the polypropylene which mixed the propylene-type elastomer resin, and shows the physical property excellent in flexibility and durability. For this reason, even if the bending distortion became large by making the thickness of the aluminum foil used for the metal thin layer 7 into 80 micrometers or more and 120 micrometers or less, a delamination will be made between the aluminum foil and the heat-adhesive resin layer 8. It is hard to generate | occur | produce or a crack in the heat-adhesive resin layer 8. Therefore, in the packaging material for electrochemical cells of this invention, it is possible to use the aluminum foil whose thickness is 80 micrometers or more and 120 micrometers or less for the metal thin layer 7, and improves the impact resistance and sticking resistance of the exterior body 10. FIG. .

In addition to the distortion caused by the thickness of the aluminum foil, the thicker the aluminum foil, the longer it takes for the heat retained in the aluminum foil to dissipate during heat sealing, and crystallization of the heat-adhesive resin layer 8 proceeds. This may cause cracks in bending of the seal portion.

However, since the heat-adhesive resin layer 8 is comprised of the polypropylene which mixed the propylene-type elastomer resin, since it has excellent heat resistance compared with other polypropylene resin, generation | occurrence | production of the said crack can be prevented.

In addition, in order to improve the generation of pinholes and to make the type of the exterior of a lithium ion battery an emboss type, there is no occurrence of cracks or the like in embossing. The iron content is preferably 0.3 to 9.0% by weight, preferably 0.7 to 2.0% by weight.

Thereby, compared with aluminum which does not contain iron, the malleability of aluminum is favorable, the generation | occurrence | production of the pinhole by bending as an exterior body reduces, and when forming embossing packaging material, a side wall can be formed easily. have. Moreover, when iron content is less than 0.3 weight%, effects, such as prevention of pinhole generation and the improvement of emboss moldability, were not confirmed, and when iron content of aluminum exceeds 9.0 weight%, the flexibility as aluminum is impaired. This results in poor umbilicality as a packaging material.

In addition, although the aluminum produced by cold rolling changes the flexibility, the strength and the hardness of the trunk under the annealing (the so-called annealing treatment) conditions, the aluminum employed in the present invention is somewhat or completely annealed than the hardened product without annealing. Aluminum tends to be soft.

That is, the annealing conditions may be appropriately selected in accordance with the processing aptitude (pouch formation, embossing). For example, in order to prevent wrinkles and pinholes at the time of embossing, annealed soft aluminum according to the shaping | molding degree can be used.

Moreover, the adhesive strength with the adhesive agent 12 and the acid-modified polyolefin layer 9 improves by forming the chemical conversion treatment layer 7a in the surface and the back surface of aluminum which is the metal thin layer 7.

Next, this chemical conversion treatment layer 7a will be described. As shown in FIG. 1, the chemical conversion treatment layer 7a is formed in the surface of the heat-adhesive resin layer 8 side of the metal thin layer 7 at least. The chemical conversion treatment layer 7a can stably bond the acid-modified polyolefin layer 9 and the metal thin layer 7 to prevent the lamination of the metal thin layer 7 and the heat-adhesive resin layer 8. In addition, the chemical conversion treatment layer 7a also has a function of preventing corrosion of aluminum.

Specifically, by forming an acid resistant film such as phosphate, chromate, fluoride, triazine thiol compound, prevention of delamination between the thin metal layer 7 and the heat-adhesive resin layer 8 during embossing molding, and lithium ion Hydrogen fluoride produced by the reaction of the battery with the electrolyte and moisture prevents the dissolution and corrosion of the aluminum surface, in particular, the dissolution and corrosion of the aluminum oxide present on the surface of the aluminum, and the adhesion of the aluminum surface (wetting). Can improve.

The chemical conversion treatment layer 7a is a metal thin layer by chromium-based chemical treatment such as chromate chromate treatment, phosphate chromate treatment, coated chromate treatment, or non-chromium (coated) chemical conversion treatment such as zirconium, titanium, zinc phosphate or the like. (7) Although it is formed on the surface, it is strongly adhered to the fluorine-based resin, and the coating type chemical conversion treatment, in particular amination, from the fact that the continuous treatment is possible and the washing process is unnecessary and the treatment cost can be reduced. It is most preferable to treat with a treatment liquid containing a phenol polymer, a trivalent chromium compound and a phosphorus compound.

Moreover, what is necessary is just to select and form a process liquid as well as the well-known coating methods, such as the bar coating method, the roll coating method, the gravure coating method, and the deposition method, as a formation method of the chemical conversion treatment layer 7a. Before forming the chemical conversion treatment layer 7a, the surface of the metal thin layer 7 is treated with a known degreasing method such as an alkali deposition method, an electrolytic cleaning method, an acid washing method, or an acid activation method in advance. It is preferable at the point which expresses the function of the layer 7a as much as possible, and can hold | maintain for a long time.

Corona treatment, blast treatment, oxidation treatment, ozone treatment, and the like are appropriately applied to each of the above layers for the purpose of appropriately improving and stabilizing film forming properties, lamination processing, and final product secondary processing (pouching, embossing) aptitude. May be surface activated.

Next, the acid-modified polyolefin layer 9 will be described. The acid-modified polyolefin layer 9 is a layer provided for bonding the thin metal layer 7 and the heat-adhesive resin layer 8, which is an inner layer of the exterior body 10, and is used for the heat-adhesive resin layer 8. Although it is necessary to select and use suitably according to the species, normally, an acid-modified polyolefin resin can be used, Specifically, the polyolefin resin graft-modified by unsaturated carboxylic acid, ethylene or propylene, acrylic acid, or air of methacrylic acid It is a copolymer or a metal crosslinked polyolefin resin, etc., If necessary, 5% or more of a butene component, an ethylene propylene- butene copolymer, an amorphous ethylene propylene copolymer, a propylene-alpha-olefin copolymer, etc. may be added.

In addition, the acid-modified polyolefin layer 9 can use the acid-modified polypropylene, and can provide the exterior body 10 which is further excellent in content resistance and adhesive strength.

When using acid-modified polypropylene,

(1) Vicat Softening Point: Homo type of 115 ° C or higher, melting point 150 ° C or higher,

(2) Vicat softening point 105 degreeC or more, copolymer with ethylene propylene which is melting | fusing point 130 degreeC or more (random copolymerization type)

(3) A single compound or a blend obtained by acid-denatured polymerization using an unsaturated carboxylic acid having a melting point of 110 ° C. or higher can be used.

Here, by adding a resin containing a propylene elastomer resin to the acid-modified polypropylene, the adhesive strength of the heat-adhesive resin layer 8 is strengthened, and the metal thin layer 7 and the heat-adhesive resin layer 8 It is effective to prevent delamination between. In addition, the flexibility and durability of the entire exterior body 10 are further improved, and the role of improving bending resistance and preventing cracks during molding is also achieved.

In addition, this invention is not limited to each embodiment mentioned above, A various change is possible and the embodiment obtained by combining suitably the technical means disclosed in each embodiment is also included in the technical scope of this invention. .

[ Example  One]

EMBODIMENT OF THE INVENTION Hereinafter, the action and effect of this invention are concretely demonstrated using an Example. Example 1 evaluates the insulation in the sealing part after heat sealing when the propylene-type elastomer resin is mixed with the polypropylene layer which comprises a heat-adhesive resin layer.

In addition, the propylene-based elastomer resin used in the present example is Nothio PN-2070 manufactured by Mitsui Chemical Corporation. This propylene elastomer resin is 71 mol% in content of the structural unit derived from propylene, and contains the structural unit derived from ethylene and the structural unit derived from 1-butene as structural units other than the structural unit derived from propylene. In addition, the physical properties of the Shore A hardness (ASTM D2240) 75, melting point 138 ℃, density (ASTM D1505) 867 kg / ㎥, glass transition temperature (Tg) of -29 ℃, haze 7%, melt flow rate (MFR, ASTM D1238) is 7.0 g / 10 min.

Next, the manufacturing method of the electrochemical cell packaging material used by a present Example is demonstrated. First, chemical conversion treatment was performed on both surfaces of aluminum, and the stretched nylon film was bonded to one chemical conversion treatment surface by a dry lamination method via a two-liquid curable polyurethane adhesive. Next, an acid-modified polypropylene (hereinafter abbreviated as "acid-modified PP") is applied and baked on the other chemical conversion surface by a roll coat method, and a two-layer random polypropylene film is described on the acid-modified PP surface (hereinafter And a three-layer coextruded film formed by inserting a block polypropylene film (hereinafter abbreviated as "block PP") (thickness 20 µm) between "random PP") (5 µm thick) in the thermal lamination method. It laminated by this and obtained the packaging material for electrochemical cells of the comparative example 1.

In the present embodiment, the base material layer is a stretched nylon film (thickness 25 μm), and the metal thin layer is aluminum (thickness 40 μm). It apply | coated by the roll coat method and baked on the conditions which become a film temperature 90 degreeC or more. Here, the coating amount of chromium was 10 mg / m <2> (dry weight), acid-modified PP was baked on the conditions which aluminum temperature becomes 140 degreeC or more, and the coating amount of acid-modified PP was 3 g / m <2> (dry weight).

Subsequently, in the lamination method of the packaging material obtained in Comparative Example 1, instead of the block PP film constituting the three-layer coextrusion film, a propylene-based elastomer resin (Nothio (registered trademark) PN-2070 manufactured by Mitsui Chemical Co., Ltd.) The packaging material for electrochemical cells which concerns on this invention 1 was obtained using the block PP film which mixed 10weight%.

Next, in the lamination method of the packaging material obtained in Comparative Example 1, instead of the block PP film constituting the three-layer coextruded film, a propylene-based elastomer resin (NOTI PTM-2070 manufactured by Mitsui Chemical Co., Ltd.) ) Was used to obtain a packaging material for an electrochemical cell according to the present invention 2, using a block PP film mixed with 20% by weight.

Subsequently, in the lamination method of the packaging material obtained in Comparative Example 1, instead of the block PP film constituting the three-layer coextrusion film, a propylene-based elastomer resin (Nothio (registered trademark) PN-2070 manufactured by Mitsui Chemical Co., Ltd.) Using a block PP film mixed with 20% by weight, a random PP film obtained by mixing 10% by weight of propylene-based elastomer resin (Nothio (registered trademark) PN-2070, manufactured by Mitsui Chemical Co., Ltd.) in place of two layers of random PP The electrochemical cell packaging material according to the present invention 3 was obtained.

Next, in the lamination method of the packaging material obtained in Comparative Example 1, instead of the block PP film constituting the three-layer coextrusion film, a propylene-based elastomer resin (NOTI PTM-2070 manufactured by Mitsui Chemical Co., Ltd.) Random PP film which mixed 20 weight% of propylene-type elastomer resins (Nothio (trademark) PN-2070 made by Mitsui Chemical Co., Ltd.) instead of two layers of random PP using 20% by weight of block PP film which mixed Using, the electrochemical cell packaging material according to the present invention 4 was obtained.

Next, the electrochemical cell packaging material of Comparative Example 1 and the present inventions 1 to 4 was cut into a sheet piece of 60 mm (MD direction) × 60 mm (TD direction), and the sheet piece was folded in half in the MD direction, The opposing two sides were heat-sealed to 7 mm width, and the pouch type exterior body which has an opening in one side was created. At this time, heat sealing was performed on condition of surface pressure 1.0 Mpa, sealing temperature 190 degreeC, and sealing time 3.0 second.

2 is a schematic plan view for explaining the evaluation method in the present embodiment. As a method for evaluating insulation at the bent portion of the outer package body after heat sealing, a case where the sheet is folded by 90 ° so as to form a fold on A-A '(see FIG. 2) on the heat seal portion of the prepared outer body is folded. This MD direction folding was repeated 20 round trips, and the lithium ion battery main body was enclosed from the opening part of the exterior body, the electrolyte solution was put, and it sealed and sealed.

Next, as shown in FIG. 2, the tip end portion of the negative electrode terminal 14b is set in the electrolyte containing the positive electrode terminal 14a so as to reach the aluminum foil of the exterior body, and the voltage meter 15 sets the voltage 25V or 100V. The resistance was measured by applying for 5 seconds. In this evaluation method, four samples of the comparative example 1 and this invention 1-4 were prepared, respectively, and the evaluation was performed twice about the applied voltage 25V and 100V, respectively. The results are shown in the table of FIG.

As mentioned above from the table | surface of FIG. 3, when a fold mark is put in the MD direction which is the orientation direction of a heat seal resin, the propylene-type elastomer resin (Nothio (trademark) PN-2070 by Mitsui Chemical Co., Ltd.) was mixed. In either case, the heat-adhesive resin layer containing the polypropylene layer had a resistance value of ∞, and cracks did not occur. However, propylene-based elastomer resin (Nothio PN-2070 manufactured by Mitsui Chemical Co., Ltd.) was used. In the heat-adhesive resin layer not containing the mixed polypropylene layer, cracks occurred and it was found that the aluminum foil was energized.

From this, the polypropylene which mixed propylene-type elastomer resin (Nothio (registered trademark) PN-2070 by Mitsui Chemical Co., Ltd.) to the heat-adhesive resin layer in the process of bending the sealing part inner edge of the outer periphery. It was found that the inclusion of the layer can suppress the occurrence of cracks and ensure the insulation of the exterior body.

[ Example  2]

Example 2 evaluates the limit moldability when the propylene-based elastomer resin is mixed with the polypropylene layer constituting the heat-adhesive resin layer.

First, the same thing as the packing material for electrochemical cells of the comparative example 1 and this invention 1-4 obtained in Example 1 was prepared, and it cut out to 80 mm x 20 mm square. Next, each sample was molded in a 30 mm x 50 mm diameter molding die (female mold) and a molding die (male mold) corresponding thereto to form a single-sided embossed type external body having a depth of 7.0 mm. The lithium ion battery main body was enclosed in the exterior body, the electrolyte solution was put, and it sealed sealing with the seal width 5mm.

Next, the positive electrode terminal was set in the electrolyte so that the tip end of the negative electrode terminal reached the aluminum foil of the exterior body, and voltages of 25 V, 100 V, 500 V, and 1000 V were applied by a voltmeter for 5 seconds to measure resistance. In this evaluation method, eight samples of Comparative Example 1 and the present inventions 1 to 4 were prepared, and each of the applied voltages was evaluated twice, and the results are shown in FIG. 4.

As is apparent from the table of FIG. 4, when the high voltage of 500 V is applied, the energization is confirmed only in Comparative Example 1, and when the high voltage of 1000 V is applied to the packaging material, the electrochemical according to Comparative Example 1 and the present invention 1 The energization was confirmed in the cell packaging material. The insulation after embossing is superior to the case where the propylene-based elastomer resin (NOTI® PN-2070 manufactured by Mitsui Chemicals Co., Ltd.) is not mixed therefrom, and the propylene-based elastomer resin (Mitsuka Chemical) It was found that the insulation after embossing was superior to the case where 20% by weight of Nothio (registered trademark) PN-2070 manufactured by Corporation was mixed with 10% by weight. Therefore, it was found that by mixing the propylene-based elastomer resin (NOTI® PN-2070 manufactured by Mitsui Chemical Co., Ltd.), the flexibility and durability of the heat-adhesive resin were improved to suppress the occurrence of cracks.

[ Example  3]

Example 3 evaluates the seal strength when the propylene-based elastomer resin is mixed with the polypropylene layer constituting the heat-adhesive resin layer.

First, the same thing as the comparative example obtained in Example 1, and the packaging material for electrochemical cells of this invention 1-4 was prepared, and it cut out to the sheet piece of 60 mm (MD direction) x 60 mm (TD direction). Next, this was folded in half in the TD direction, and the two opposite sides were heat sealed to a width of 7 mm to form a pouch-shaped exterior body having an opening on one side, and the opening was 7 mm wide, a surface pressure of 1.0 MPa, and a seal. Heat seal with a ring time of 3.0 seconds. At this time, the sealing temperature was changed to 150 degreeC, 170 degreeC, 190 degreeC, and 210 degreeC, and the sample was produced.

Next, the heat seal part in the said opening part of these samples was cut | disconnected in strip shape of 15 mm width, and this was pulled at the speed | rate of 300 mm / min by the tension machine (made by Shimadzu Corporation, AGS-50D (brand name)). , Heat seal strength was measured. The unit is N / 15 mm wide.

The relationship between the sealing temperature and the seal strength measured for Comparative Example 1 and the electrochemical cell packaging material of the present inventions 1 to 4 is shown in the graph of FIG. 5. As is apparent from this graph, it is found that the heat-adhesive resin according to the present invention 2 strengthens the seal strength at a sealing temperature of 150 ° C to 200 ° C as compared with the heat-adhesive resin according to Comparative Example 1 and the present invention 1. Could. Moreover, it turned out that the heat-adhesive resin which concerns on this invention 4 also strengthens sealing strength in the sealing temperature of 150 degreeC-200 degreeC compared with the heat-adhesive resin which concerns on this invention 3 similarly. Accordingly, it was found that the seal strength of the block PP film and the random PP film increased by increasing the mixing amount of the propylene-based elastomer resin (NOTI® PN-2070 manufactured by Mitsui Chemicals Co., Ltd.). Moreover, it turned out that especially the amount of change of seal strength is large when mixing a propylene-type elastomer resin in a block PP film.

Therefore, although heat of around 190 ° C. is usually applied as the heat sealing temperature and the strength of about 80 N / 15 mm is required as the seal strength, when the electrochemical cell packaging material of the present invention 1 is used, it is 80 N / 15 with heat around 175 ° C. Strength of about mm can be obtained. Therefore, low temperature sealing property can be ensured and the manufacturing efficiency of a lithium ion battery can be improved.

[ Example  4]

Example 4 evaluates the insulation property in the sealing part after heat sealing in the case where the thickness of a metal thin layer is provided thick and the propylene-type elastomer resin is mixed with the polypropylene layer which comprises a heat-adhesive resin layer. .

First, in Comparative Example 1 used in Example 1 and the electrochemical cell packaging materials of the present inventions 1 and 2, the electrochemical cell packaging material prepared by using aluminum having a thickness of 100 μm for the metal thin layer, respectively, was Comparative Example 2, the present invention. As 5 and this invention 6, each electrochemical cell packaging material was cut out to the sheet piece of 60 mm (MD direction) x 60 mm (TD direction). Next, this sheet piece was folded in half in the MD direction, and the two opposite sides were heat-sealed in a width of 7 mm to create a pouch-shaped exterior body having an opening on one side. At this time, heat sealing was performed on condition of surface pressure 1.0 Mpa, sealing temperature 190 degreeC, and sealing time 3.0 second.

Next, the case of folding 90 ° so as to be folded at A-A '(see FIG. 2) on the heat seal portion of the prepared outer package was called MD direction folding. After this MD direction folding was repeated 5 times round-trip, the lithium ion battery main body was enclosed from the opening part of the exterior body, the electrolyte solution was put, and it sealed sealed.

Next, as shown in FIG. 2, the tip end portion of the negative electrode terminal 14b is set in the electrolyte containing the positive electrode terminal 14a so as to reach the aluminum foil of the exterior body, and the voltage meter 15 sets the voltage 25V or 100V to 5. The resistance value was measured by applying for a second. In this evaluation method, four samples of the comparative example 2 and this invention 5, 6 were prepared, respectively, and evaluation was performed twice about the applied voltage 25V and 100V with respect to MD direction folding. The results are shown in the table of FIG.

As is apparent from the table of FIG. 6, when the folds are inserted in the MD direction, which is the orientation direction of the heat-adhesive resin, the propylene-based elastomer resin (Mitsuika Gakuku) is used in the block PP even when the thickness of the aluminum of the base layer is 100 μm. It was found that generation of cracks can be suppressed by mixing Nothio PN-2070 manufactured by Corporation.

Therefore, if the aluminum foil of the exterior body is thick, it takes time until the heat retained in the aluminum foil during heat sealing dissipates, and the crystallization of the heat-adhesive resin proceeds, which causes this to cause cracks in the bending of the seal portion. Although it may be mentioned, generation | occurrence | production of a crack can be suppressed because a heat-adhesive resin layer is comprised from the block PP which mixed the propylene-type elastomer resin.

[ Example  5]

Example 5 evaluates the seal strength when the propylene-based elastomer resin is mixed with the acid-modified polypropylene layer.

First, chemical conversion treatment is performed on both surfaces of an aluminum foil (40 µm thick), and a stretched nylon film (thickness 100 µm) is bonded to one chemical conversion surface by a dry lamination method via a two-liquid curable polyurethane adhesive. The acid-modified PP (15 micrometers in thickness) was melt-extruded on the other chemical conversion surface, and the ethylene-propylene block copolymer film (20 micrometers in thickness) was formed between two layers of ethylene-propylene random copolymer films (5 micrometers in thickness). The packaging material for electrochemical cells obtained by laminating | stacking the film for sealants which consists of a 3-layer coextrusion film formed by lamination | stacking by the thermal lamination method was made into the comparative example 3.

In addition, in the same manner as the electrochemical cell packaging material obtained in Comparative Example 3, an acid obtained by mixing 10% by weight of propylene-based elastomer resin (Nothio (registered trademark) PN-2070 manufactured by Mitsui Chemical Co., Ltd.) was used instead of acid-modified PP. The electrochemical cell packaging material laminated | stacked using modified PP was made into this invention 7, and similarly, instead of acid-modified PP, the propylene-type elastomer resin (Nothio (trademark) PN-2070 by Mitsui Chemical Co., Ltd.) was 20 The packaging material for electrochemical cells laminated | stacked using the acid-modified PP mixed by weight% was made into this invention 8.

At this time, the chemical conversion treatment was applied by a roll coating method using an aqueous solution made of a phenol resin, a chromium fluoride compound, and phosphoric acid as the treatment liquid, and calcined under the condition that the film temperature was 180 ° C or higher. In addition, the coating amount of chromium was 10 mg / m <2> (dry weight). Acid-modified PP was apply | coated by the roll coat method, and it baked on the conditions made aluminum temperature 180 degreeC or more. The coating amount of acid-modified PP was made into 3 g / m <2> (dry weight).

Next, the electrochemical cell packaging material of Comparative Example 3 and the present inventions 7, 8 was cut into a sheet piece of 60 mm (MD direction) x 60 mm (TD direction), which was folded in half in the TD direction and opposed to 2. The sides were heat sealed to a width of 7 mm to form a pouch-shaped exterior body having an opening on one side, and the opening of the exterior body was heat sealed at a width of 7 mm, a surface pressure of 1.0 MPa and a sealing time of 3.0 seconds. At this time, the sample which sealed by changing conditions to 150 degreeC, 170 degreeC, 190 degreeC, and 210 degreeC of sealing temperature was produced for every said laminated body.

Next, the heat seal part in the said opening part of these samples was cut | disconnected in strip shape of 15 mm width, and this was pulled at the speed | rate of 300 mm / min by the tension machine (made by Shimadzu Corporation, AGS-50D (brand name)). , Heat seal strength was measured. The unit is N / 15 mm wide.

As described above, the relationship between the sealing temperature and the seal strength measured for the electrochemical cell packaging material of Comparative Example 3 and the present inventions 7, 8 is shown in the graph of FIG. 7. Acid-modified PP which increased the mixing amount of propylene-type elastomer resin (Nothio (trademark) PN-2070 by Mitsui Chemical Co., Ltd.) from the point which seal strength improves in the order of this invention 8, this invention 7, and the comparative example 3. It turns out that the sealing strength of a heat-adhesive resin layer increases more.

[ Example  6]

Example 6 evaluated the seal strength at the time of mixing a propylene-type elastomer resin with the melt-extruded polypropylene layer which comprises an acid-modified polypropylene layer and a heat-adhesive resin layer.

A chemical conversion treatment is performed on both surfaces of an aluminum foil (100 µm thick), and a stretched nylon film (25 µm thick) is bonded to one chemical conversion surface by a dry lamination method via a two-liquid curing type polyurethane adhesive, and the other The acid-modified PP (15 micrometers in thickness) which mixed 20 weight% of propylene-type elastomer resins (NOTI® PN-2070 by Mitsui Chemical Co., Ltd.) with respect to acid-modified PP on a chemical conversion surface was melt-extruded, PP was melt-extruded so as to be 30 micrometers in thickness, and the laminated body which concerns on this invention 9 was obtained.

At this time, the chemical conversion treatment was applied by a roll coating method using an aqueous solution composed of a phenol resin, a chromium fluoride compound, and phosphoric acid as a treatment liquid, and calcined under the condition that the film temperature was 180 ° C or higher. In addition, the coating amount of chromium was 10 mg / m <2> (dry weight). Acid-modified PP was apply | coated by the roll coat method, and it baked on the conditions made aluminum temperature 180 degreeC or more. The coating amount of acid-modified PP was made into 3 g / m <2> (dry weight).

Next, the random PP which mixed 20 weight% of propylene-type elastomer resins (Nothio (trademark) PN-2070 by Mitsui Chemical Co., Ltd.) with respect to polypropylene resin instead of random PP by the lamination method similar to this invention 9 To a laminate obtained by melt extrusion to a thickness of 30 μm as the present invention 10, and a laminate obtained by melt extrusion of a homo PP to a thickness of 30 μm as the present invention 11 instead of the random PP. The laminated body obtained by melt-extruding the homo PP which mixed 20 weight% of propylene-type elastomer resin (NOTI® PN-2070 by Mitsui Chemicals Co., Ltd.) with respect to polypropylene resin so that it may be set to thickness of 30 micrometers is referred to as this invention 12. It was.

In addition, the propylene-based elastomer resin (with respect to the homo-PP and the polypropylene resin in which 20% by weight of propylene-based elastomer resin (NOTI® PN-2070 manufactured by Mitsui Chemical Co., Ltd.) was mixed with respect to the polypropylene resin instead of the random PP The laminated body obtained by melt-extruding the random PP which mixed 20 weight% of Nothio (trademark) PN-2070 by Mitsui Chemical Co., Ltd. to make thickness 30micrometer was made into this invention 13.

Next, the laminated body of this invention 9-13 was cut out to the sheet piece of 60 mm (MD direction) x 60 mm (TD direction), it is folded in half in the TD direction, and the two sides which oppose are heated by 7 mm width. The pouch-shaped exterior body which sealed and created opening in one side was created, and the opening part of the exterior body was heat-sealed with 7 mm width, surface pressure 1.0 Mpa, and sealing time 3.0 second. At this time, the sample which sealed by changing conditions to 150 degreeC, 170 degreeC, 190 degreeC, and 210 degreeC of sealing temperature was produced for every said laminated body.

Next, the heat seal part in the said opening part of these samples is cut | disconnected in strip shape of 15 mm width, and this is pulled at the speed | rate of 300 mm / min by the tension machine (made by Shimadzu Corporation, AGS-50D (brand name)). And the heat seal strength was measured. The unit is N / 15 mm wide.

As mentioned above, the relationship of the sealing temperature and seal strength measured about the electrochemical cell packaging material of this invention 9-13 is shown in the graph of FIG. As is clear from this graph, the propylene elastomer resin (NOTI® PN-2070, manufactured by Mitsui Chemical Co., Ltd.) was mixed with acid-modified PP, random PP, and homo PP, so that the seal strength of the laminate was changed to all sealing temperatures. It was found to increase.

[ Example  7]

Example 7 evaluates the seal strength and the laminate strength when the propylene-based elastomer resin is mixed with acid-modified PP.

A chemical conversion treatment is performed on both surfaces of an aluminum foil (40 µm thick), and a stretched nylon film (25 µm thick) is bonded to one chemical conversion surface by a dry lamination method via a two-liquid curing type polyurethane adhesive, and the other The acid-modified PP (thickness 15 micrometers) was melt-extruded on the chemical conversion process surface, and the film for sealants which consisted of an unstretched polypropylene film (thickness 30 micrometers) was laminated | stacked by the thermal lamination method, and the comparative example 4 was obtained.

In the same manner as in the laminate obtained in Comparative Example 4, using acid-modified PP obtained by mixing 10% by weight of propylene-based elastomer resin (Nothio (registered trademark) PN-2070 manufactured by Mitsui Chemical Co., Ltd.) in place of acid-modified PP, The obtained laminated body as this invention 14, The laminated body obtained using acid-modified PP which mixed 20 weight% of propylene-type elastomer resin (NOTI® PN-2070 by Mitsui Chemical Co., Ltd.) instead of acid-modified PP. It was set as the present invention 15.

At this time, the chemical conversion treatment was applied by a roll coating method using an aqueous solution made of a phenol resin, a chromium fluoride compound, and phosphoric acid as the treatment liquid, and calcined under the condition that the film temperature was 180 ° C or higher. In addition, the coating amount of chromium was 10 mg / m <2> (dry weight). Acid-modified polypropylene (abbreviated as "acid-modified PP" hereafter) was apply | coated by the roll coat method, and it baked on the conditions which aluminum temperature becomes 180 degreeC or more. The coating amount of acid-modified PP was made into 3 g / m <2> (dry weight).

Next, the laminated body of the comparative example 4 and this invention 14, 15 was cut out by the sheet piece of 60 mm (MD direction) x 60 mm (TD direction), it is folded in half in the TD direction, and the two sides which oppose are 7 A pouch-shaped exterior body having an opening on one side was heat-sealed with a mm width, and the opening of the exterior body was heat-sealed with a width of 7 mm, a surface pressure of 1.0 MPa and a sealing time of 3.0 seconds. At this time, the sample sealed with the sealing temperature as 190 degreeC was produced for every said laminated body.

Subsequently, the heat seal part in the opening part of these samples was cut | disconnected in strip shape of 15 mm width, and both ends were pulled at the speed | rate of 300 mm / min by the tension machine (made by Shimadzu Corporation, AGS-50D (brand name)). , Heat seal strength was measured. The unit is N / 15 mm wide.

As mentioned above, the relationship of the propylene-type elastomer resin addition amount and the seal strength measured about the packaging material for electrochemical cells of the comparative example 4, this invention 14, 15 is shown in the graph of FIG. As is clear from this graph, it was found that the seal strength of the laminate increased in proportion to the amount of the propylene-based elastomer resin (NOTI® PN-2070 manufactured by Mitsui Chemical Co., Ltd.) mixed with the acid-modified PP.

Moreover, the laminated body of the comparative example 4 and this invention 14, 15 was cut out by the sheet piece of 60 mm (MD direction) x 60 mm (TD direction), it is folded in half in the TD direction, and the two sides which oppose are 7 mm. The bag was heat-sealed in width, and the bag which had an opening in one side was created, and the opening part was heat-sealed on the same conditions as the above conditions with 7 mm width, surface pressure 1.0 Mpa, and sealing time 3.0 second. Next, both the heat-sealed laminates are peeled off to measure the laminate strength and are shown in the graph of FIG. 9. As is clear from this graph, it was found that the laminate strength was not affected by the amount of propylene-based elastomer resin (NOTI® PN-2070 manufactured by Mitsui Chemical Co., Ltd.).

In addition, about the laminated body of the comparative example 4 and this invention 14, 15, the measurement environmental temperature was changed to 25 degreeC, 120 degreeC, and 140 degreeC, and it measured about seal strength and laminate strength by the method similar to the said method, and the result Is shown in the graph of FIG. As is apparent from this metal terminal block, a laminate obtained using an acid-modified PP obtained by mixing 20% by weight of a propylene-based elastomer resin (NOTI® PN-2070 manufactured by Mitsui Chemical Co., Ltd.) was subjected to changes in environmental temperature. It was found that stable seal strength was maintained.

[ Example  8]

Example 8 evaluates the insulation in the sealing part after heat sealing when the propylene-type elastomer resin is mixed with the polypropylene layer which comprises a heat-adhesive resin layer.

In addition, the propylene-based elastomer resin used in the present example is Nothio (registered trademark) PN-2060 manufactured by Mitsui Chemical Corporation. The content of the structural unit derived from propylene is 79 mol%, and this propylene elastomer resin contains the structural unit derived from ethylene, and the structural unit derived from 1-butene as structural units other than the structural unit derived from propylene. In addition, the physical properties of the Shore A hardness (ASTM D2240) 82, melting point 155 ℃, density (ASTM D1505) 868 kg / ㎥, glass transition temperature (Tg) of -28 ℃, haze 4%, melt flow rate (MFR, ASTM D1238) is 6.0 g / 10 min.

Next, the manufacturing method of the electrochemical cell packaging material used by a present Example is demonstrated. First, chemical conversion treatment was performed on both surfaces of aluminum, and the stretched nylon film was bonded to the one chemical conversion treatment surface by the dry lamination method via a two-component curable polyurethane adhesive. Subsequently, acid-modified PP is apply | coated and baked on the other chemical conversion surface by the roll coat method, and a block PP (thickness 20 micrometers) is inserted between two layers of random PP (5 micrometers thickness) on the acid-modified PP surface. The three-layer coextrusion film thus formed was laminated by a thermal lamination method to obtain an electrochemical cell packaging material.

In this embodiment, the base material layer is a stretched nylon film (thickness 25 μm), and the metal thin layer is aluminum (thickness 40 μm), and the chemical conversion treatment layer is made of a phenol resin, a chromium fluoride compound, and a phosphoric acid. It apply | coated by the roll coat method and baked on the conditions which become a film temperature 90 degreeC or more. Here, the coating amount of chromium is 10 mg / m 2 (dry weight), the acid-modified PP is calcined under the condition that the aluminum temperature is 140 ° C. or higher, and the coating amount of the acid-modified PP is 3 g / m 2 (dry weight). It was.

Next, in the lamination method of the said packaging material, 10 weight% of propylene-type elastomer resin (Nothio (trademark) PN-2060 by Mitsui Chemical Co., Ltd.) was mixed with the block PP film which comprises a 3-layer coextrusion film. The packaging material for electrochemical cells which concerns on this invention 16 was obtained using the block PP film.

Subsequently, in the lamination method of the said packaging material, the block which mixed 20 weight% of propylene-type elastomer resins (Nothio (trademark) PN-2060 by Mitsui Chemical Co., Ltd.) to the block PP film which comprises a 3-layer coextrusion film. The packaging material for electrochemical cells which concerns on this invention 17 was obtained using a PP film.

Next, in the lamination method of the said packaging material, 20 weight% of propylene-type elastomer resins (Nothio (trademark) PN-2060 by Mitsui Chemical Co., Ltd.) were mixed with the block PP film which comprises a 3-layer coextrusion film. Using a block PP film, the random PP film which mixed 10 weight% of propylene-type elastomer resins (Nothio (trademark) PN-2060 by Mitsui Chemical Co., Ltd.) to two layers of random PP about this invention 18 An electrochemical cell packaging material was obtained.

Next, in the lamination method of the packaging material, 20% by weight of a propylene-based elastomer resin (Nothio (registered trademark) PN-2060 manufactured by Mitsui Chemical Co., Ltd.) is mixed with the block PP film constituting the three-layer coextrusion film. In the present invention 19 using a random PP film in which 20% by weight of a propylene-based elastomer resin (Nothio (registered trademark) PN-2060 manufactured by Mitsui Chemical Co., Ltd.) was mixed with two layers of random PP using a single block PP film. A packaging material for electrochemical cells was obtained.

Next, the electrochemical cell packaging material of the present invention 16 to 19 is cut into a sheet piece having a thickness of 60 mm (MD direction) x 60 mm (TD direction), and the sheet piece is folded in half in the MD direction and opposed to each other. The pouch type exterior body which had an opening on one side was heat-sealed by 7 mm width | variety. At this time, heat sealing was performed on condition of surface pressure 1.0 Mpa, sealing temperature 190 degreeC, and sealing time 3.0 second.

2 is a schematic plan view for explaining the evaluation method in the present embodiment. As a method for evaluating insulation at the bent portion of the outer package body after heat sealing, a case where the sheet is folded by 90 ° so as to form a fold on A-A '(see FIG. 2) on the heat seal portion of the prepared outer body is folded. This MD direction folding was repeated 20 round trips, and the lithium ion battery main body was enclosed rather than the opening part of the exterior body, the electrolyte solution was put, and it sealed and sealed.

Next, as shown in FIG. 2, the tip end portion of the negative electrode terminal 14b is set in the electrolytic solution sealed with the positive electrode terminal 14a so as to reach the aluminum foil of the exterior body, and the voltage meter 15 causes the voltage 25V or 100V. Was applied for 5 seconds to measure resistance. In this evaluation method, four samples of this invention 16-19 were prepared, respectively, and it evaluated twice about the applied voltage 25V and 100V, respectively. The results are shown in the table of FIG.

As mentioned above from the table | surface of FIG. 11, when a fold mark is put in MD direction which is the orientation direction of a heat-sealing resin, propylene-type elastomer resin (Nothio (trademark) PN-2060 by Mitsui Chemical Co., Ltd.) is made into In either case, in the heat-adhesive resin layer containing the mixed polypropylene layer, the resistance value was ∞ and cracks did not occur.

From this, in the step of bending the seal inner edge of the outer periphery, a polypropylene layer obtained by mixing a propylene-based elastomer resin (Nothio (registered trademark) PN-2060 manufactured by Mitsui Chemical Co., Ltd.) with a heat-adhesive resin layer It was found that the inclusion of the present invention can suppress the occurrence of cracks and ensure the insulation of the exterior body.

By confirming the above-mentioned examples, the properties of the acid-modified polyolefin layer and the heat-adhesive resin layer are improved by mixing propylene-based elastomer resins (NOTI® PN-2070, PN-2060 manufactured by Mitsui Chemical Co., Ltd.). It became.

1 is a schematic cross-sectional view showing the layer structure of the packaging material for an electrochemical cell of the present invention;

2 is a schematic plan view of a lithium ion battery for explaining an evaluation method in an embodiment of the present invention;

3 is a table showing the insulation of the packaging material for an electrochemical cell of the present invention in Example 1;

4 is a table showing the insulation of the packaging material for an electrochemical cell of the present invention in Example 2;

5 is a graph showing the seal strength of the packaging material for an electrochemical cell of the present invention in Example 3. FIG.

6 is a table showing the insulation properties of the packaging material for an electrochemical cell of the present invention in Example 4;

7 is a graph showing the seal strength of the packaging material for an electrochemical cell of the present invention in Example 5;

8 is a graph showing the seal strength of the packaging material for an electrochemical cell of the present invention in Example 6;

9 is a graph showing the seal strength and laminate strength of the packaging material for an electrochemical cell of the present invention in Example 7;

10 is a graph showing seal strength and laminate strength of an electrochemical cell packaging material of Example 7;

11 is a table showing the insulation properties of the packaging material for an electrochemical cell of the present invention in Example 8;

12A is a schematic perspective view showing a conventional pouch type lithium ion battery;

12B is a schematic perspective view showing an exploded view of a conventional pouch type lithium ion battery;

13A is a schematic perspective view showing a conventional embossed lithium ion battery;

Fig. 13B is a schematic perspective view showing an exploded view of a conventional embossed lithium ion battery;

14A is a schematic perspective view of a conventional lithium ion battery;

14B is a schematic perspective view showing a conventional lithium ion battery housed in a plastic case;

14C is a cross-sectional view showing a conventional lithium ion battery housed in a plastic case;

<Explanation of symbols for main parts of the drawings>

6: base material layer 7: thin metal layer

7a: chemical conversion treatment layer 8: heat adhesive resin layer

9: acid-modified polyolefin layer 10: exterior body

11: protective layer 12: adhesive layer

Claims (3)

Base layer; A metal thin layer having a chemical conversion treatment layer on at least one surface thereof; Acid-modified polyolefin layer; And a heat adhesive resin layer is laminated at least sequentially, The acid-modified polyolefin layer is a resin layer composed of an acid-modified polyolefin resin, The heat adhesive resin layer has a resin layer composed of propylene resin, At least one of the acid-modified polyolefin resin or the propylene resin is mixed with a propylene elastomer resin, The propylene-based elastomer resin is a copolymer consisting of a structural unit derived from propylene and a structural unit derived from α-olefin except propylene with 2 to 20 carbon atoms, When the sum total of the structural unit derived from the said propylene, and the structural unit derived from the said (alpha) -olefin is 100 mol%, the structural unit derived from the said propylene is 50 mol% or more, (a) Shore A hardness (ASTM D2240) is 65 to 90, (b) the melting point is from 130 to 170 ° C; (c) a density (ASTM D1505) is 860 to 875 kg / m 3; (d) Packaging material for flat electrochemical cells whose glass transition temperature by DSC measurement is -25 degreeC--35 degreeC. The packaging material for flat electrochemical cells according to claim 1, wherein the propylene elastomer resin is mixed in an amount of 3% by weight or more and 30% by weight or less with respect to the propylene resin. The packaging material for a flat electrochemical cell according to claim 1 or 2, wherein the metal thin layer is an aluminum foil having a thickness of 80 µm or more and 120 µm or less.

Images