JP6595634B2 - Packaging materials and molded cases - Google Patents

Description

  The present invention is, for example, a packaging material suitably used as a case for a laptop computer, a mobile phone, a vehicle-mounted, a stationary secondary battery (lithium ion secondary battery), a food packaging material, or a pharmaceutical packaging material. It is related with the packaging material used suitably as.

  In this specification, the term “tensile yield strength” is measured in accordance with JIS K7127-1999 (tensile test method) under the conditions of a sample width of 15 mm, a distance between grades of 50 mm, and a tensile speed of 300 mm / min. It means the obtained tensile yield strength (tensile yield strength).

  In this specification, the term “aluminum” is used to include aluminum and its alloys. Further, the term “metal” is used to include a metal simple substance and a metal alloy.

  In order to prevent chemical changes, deterioration, decay, etc. of the contents of food, pharmaceuticals, etc. in the packaging material, laminate packaging materials using metal foils with excellent oxygen and moisture barrier properties have been widely used. ing.

  On the other hand, in recent years, with the reduction in size and weight of various electronic devices such as OA devices such as personal computers, mobile phones, game machines, headphone stereos, electronic notebooks, etc., the viewpoint of reducing the size and weight of the battery of the power supply unit Therefore, lithium ion polymer secondary batteries are often used. In this lithium ion polymer secondary battery, when the electrolytic solution in the battery reacts with water to generate hydrofluoric acid, the performance of the battery deteriorates, or liquid leakage occurs due to corrosion of the aluminum foil. As a material used for a case (accommodating case) of a lithium ion polymer secondary battery, a laminate packaging material having a high sealing property using a metal foil having an excellent water vapor barrier property has been used.

  Case materials (packaging materials) for lithium ion polymer secondary batteries include an outer layer made of a heat-resistant resin film, an aluminum foil layer as a water vapor barrier layer, and an inner side made of a polyolefin film for sealing the polymer electrolyte of the contents A laminate packaging material in which layers (sealant layers) are sequentially laminated and integrated is used.

  The laminate packaging material is required to have sufficient sealing strength between the inner layers of the two packaging materials so that the polymer electrolyte of the contents does not leak out.

  This type of battery packaging material is made of a coextruded polypropylene resin with two or more sealant layers, and the laminated side is made of a resin blended with homopolypropylene and polyethylene or a resin blended with random copolymer polypropylene. In addition, a structure in which the sealing surface side is made of a resin blended with homopolypropylene or further with random copolymer polypropylene is known (see Patent Document 1).

  The heat seal layer has at least a first polypropylene layer and a second polypropylene layer, and the second polypropylene layer is disposed on the innermost layer side of the first polypropylene layer, has a low melting point, and a high melt index. Is known (see Patent Document 2).

JP 2006-134692 A JP 2007-294380 A

  By the way, in the laminate packaging material, the adhesion between the outer layer, the aluminum foil layer, and the inner layer is performed by a dry laminating method using an adhesive, and the produced packaging material is wound around a core. Then, in order to accelerate | stimulate hardening of an adhesive agent, it uses for the aging process which heats at about 40 degreeC.

  However, conventionally, there has been a problem that wrinkles are likely to occur in the packaging material wound around the core due to this aging treatment. When such wrinkles occur, the appearance quality as a packaging material decreases.

  Further, the battery packaging material is required to have higher sealing strength.

  The present invention has been made in view of such a technical background, and an object of the present invention is to provide a packaging material that can obtain sufficient seal strength and that has almost no wrinkles and is excellent in appearance quality.

  In order to achieve the above object, the present invention provides the following means.

[1] A packaging material comprising a heat-resistant resin layer as an outer layer, a thermoplastic resin film layer as an inner layer, and a metal foil layer disposed between both layers,
As the thermoplastic resin film,
The tensile yield strength in the film extrusion direction is 15 MPa or more, the tensile yield strength in the direction perpendicular to the film extrusion direction is 15 MPa or more, and the tensile yield strength in the direction of 45 degrees diagonally to the film extrusion direction is 15 MPa or more, A packaging material, wherein a thermoplastic resin film having a tensile yield strength of 15 MPa or more in a direction obliquely 45 degrees to the left with respect to the film extrusion direction is used.

[2] As the thermoplastic resin film,
The tensile yield strength in the film extrusion direction is 15 MPa to 25 MPa, the tensile yield strength in the direction orthogonal to the film extrusion direction is 15 MPa to 25 MPa, and the tensile yield strength in the direction of 45 degrees obliquely to the right with respect to the film extrusion direction is 15 MPa. The packaging material according to the preceding item 1, wherein a thermoplastic resin film having a tensile yield strength of 15 MPa to 25 MPa in a direction oblique to left by 45 degrees with respect to the film extrusion direction is used.

  [3] The tensile yield strength of the thermoplastic resin film in the film extrusion direction is “V”, the tensile yield strength in the direction perpendicular to the film extrusion direction is “W”, and the film is obliquely rightward with respect to the film extrusion direction. When the tensile yield strength in the direction of 45 degrees is "X" and the tensile yield strength in the direction of 45 degrees oblique to the left with respect to the film extrusion direction is "Y", the following three relational expressions hold. 3. A packaging material according to item 1 or 2 above.

W / V ≧ 0.85
X / V ≧ 0.88
Y / V ≧ 0.88
[4] The thermoplastic resin film layer is a layer containing one or more polymers selected from the group consisting of homopolypropylene, block copolymerized polypropylene, random copolymerized polypropylene, and ethylene-propylene copolymer rubber. 4. The packaging material according to any one of items 1 to 3, wherein the packaging material comprises at least one layer.

  [5] The thermoplastic resin film layer is a laminated film in which a coating layer containing a random copolymer polypropylene is laminated and integrated on both surfaces of an intermediate layer containing a block copolymer polypropylene. 4. The packaging material according to any one of 3 above.

  [6] The thermoplastic resin film layer is a laminated film in which a coating layer containing random copolymerized polypropylene is laminated and integrated on both surfaces of an intermediate layer containing homopolypropylene and ethylene-propylene copolymer rubber. The packaging material according to any one of items 1 to 3, which is

  [7] A molded case formed by deep-drawing or stretch-molding the packaging material according to any one of items 1 to 6.

  [8] The molded case according to item 7 used as a battery case.

  In the invention of [1], as the thermoplastic resin film constituting the inner layer, a thermoplastic resin film having a tensile yield strength of 15 MPa or more in all four specific directions is used. Almost no wrinkle is generated, the appearance quality is excellent, and sufficient seal strength is obtained. Since the tensile yield strength in the above four specific directions of the thermoplastic resin film constituting the inner layer is 15 MPa or more, the packaging material obtained by lamination is wound around the core, and the adhesive Even if heat treatment (aging treatment; for example, 40 ° C.) is performed to accelerate curing, generation of wrinkles due to stress due to shrinkage is suppressed.

  In the invention of [2], as the thermoplastic resin film constituting the inner layer, a thermoplastic resin film having a tensile yield strength in the specific four directions of 15 MPa or more and 25 MPa or less is used. Even if the aging process is performed in a wound state, the generation of wrinkles can be further suppressed and the appearance quality of the packaging material can be further improved.

In the invention of [3], as the thermoplastic resin film constituting the inner layer,
W / V ≧ 0.85
X / V ≧ 0.88
Y / V ≧ 0.88
Since the thermoplastic resin film satisfying the above three relational expressions is used, even if the aging treatment is performed in a state wound on the core, the generation of wrinkles can be further suppressed. The appearance quality of the packaging material can be further improved.

  In the invention of [4], the thermoplastic resin film layer contains one or more polymers selected from the group consisting of homopolypropylene, block copolymerized polypropylene, random copolymerized polypropylene, and ethylene-propylene copolymer rubber. Therefore, it is possible to secure a sufficient sealing strength and to sufficiently suppress the generation of wrinkles even when the aging process is performed in a state of being wound around the core.

  In the invention of [5], the thermoplastic resin film layer is composed of a laminated film in which a coating layer containing a random copolymer polypropylene is laminated and integrated on both surfaces of an intermediate layer containing a block copolymer polypropylene. Since the intermediate layer contains block copolymerized polypropylene, sufficient impact strength and sufficient piercing strength can be obtained, and a coating layer comprising random copolymerized polypropylene on both sides of the intermediate layer is laminated and integrated Therefore, sufficient seal strength can be secured.

  In the invention of [6], in the thermoplastic resin film layer, a coating layer containing random copolymer polypropylene is laminated and integrated on both surfaces of an intermediate layer containing homopolypropylene and ethylene-propylene copolymer rubber. Since the intermediate layer contains homopolypropylene with a high melting point, sufficient thickness after sealing (wall thickness of the inner layer) is required to obtain sufficient insulation. In addition, since the layers containing random copolymer polypropylene are laminated and integrated on both surfaces of the intermediate layer, sufficient sealing strength can be secured. Furthermore, since the intermediate layer also contains ethylene-propylene copolymer rubber, sufficient impact strength and sufficient piercing strength can be obtained.

  In the invention of [7], a molded case having sufficient sealing strength and having almost no wrinkles and excellent appearance quality is provided.

  In the invention of [8], a battery case that provides sufficient sealing strength and has almost no wrinkles and excellent appearance quality is provided.

It is sectional drawing which shows one Embodiment of the packaging material which concerns on this invention. It is a top view of the thermoplastic resin film for demonstrating four measurement directions at the time of measuring the tensile yield strength of a thermoplastic resin film. It is sectional drawing which shows an example of the laminated structure of a thermoplastic resin film. It is a schematic sectional drawing which shows one Embodiment of the battery comprised using the packaging material which concerns on this invention.

  One embodiment of a packaging material 1 according to the present invention is shown in FIG. This packaging material 1 is used as a packaging material for a lithium ion secondary battery case. That is, the packaging material 1 is used as a secondary battery case after being subjected to molding such as deep drawing.

  The packaging material 1 has a heat-resistant resin layer (outer layer) 2 laminated and integrated on the upper surface of the metal foil layer 4 via a first adhesive layer 5 and second bonded to the lower surface of the metal foil layer 4. The thermoplastic resin film layer (inner layer) 3 is laminated and integrated through the agent layer 6 (see FIG. 1). The configuration of each layer will be described below.

  The thermoplastic resin film layer (inner layer; heat seal layer) 3 has excellent chemical resistance against highly corrosive electrolytes used in lithium ion secondary batteries, etc. It plays a role of imparting heat-sealing properties.

  In the present invention, as the thermoplastic resin film 3, the tensile yield strength in the film extrusion direction e is 15 MPa or more, the tensile yield strength in the direction f perpendicular to the film extrusion direction is 15 MPa or more, and the right side with respect to the film extrusion direction. A thermoplastic resin film having a tensile yield strength of 15 MPa or more in a direction g of 45 degrees oblique and a tensile yield strength in a direction h of 45 degrees oblique to the left with respect to the film extrusion direction is used (FIG. 2). reference).

That is, the thermoplastic resin film 3 used as the inner layer 3 in the present invention is:
1) The tensile yield strength in the film extrusion direction (hereinafter sometimes referred to as “MD direction”) e is 15 MPa or more,
2) The tensile yield strength in the direction (hereinafter sometimes referred to as “TD direction”) f orthogonal to the film extrusion direction in the plane of the film 3 is 15 MPa or more,
3) The tensile yield strength in the direction g of 45 degrees diagonally to the right (in plan view) with respect to the film extrusion direction in the plane of the film 3 is 15 MPa or more,
4) Within the plane of the film 3, the tensile yield strength in the direction h of 45 degrees diagonally to the left (in plan view) with respect to the film extrusion direction is 15 MPa or more (see FIG. 2). A detailed method for measuring the tensile yield strength will be described later. The “tensile yield strength” means the tensile yield strength of the laminate when the thermoplastic resin film layer 3 is formed of a laminate of a plurality of films.

  In the present invention, as the thermoplastic resin film constituting the inner layer 3, a thermoplastic resin film having a tensile yield strength in the specific four directions (e, f, g, h) of 15 MPa or more is used. Thus, the packaging material 1 has little appearance of wrinkles and is excellent in appearance quality even when going through an aging treatment in a state of being wound around a core, and sufficient sealing strength can be obtained. . That is, since the tensile yield strength in the above four specific directions of the thermoplastic resin film constituting the inner layer 3 is 15 MPa or more, the packaging material 1 obtained by laminating the thermoplastic resin film has the core Even when a heat treatment (aging treatment; for example, 40 ° C.) is performed in order to accelerate the curing of the adhesive in the state of being wound around, the generation of wrinkles due to shrinkage stress or the like in the packaging material 1 can be suppressed.

  Among them, as the thermoplastic resin film constituting the inner layer 3, it is preferable to use a thermoplastic resin film having a tensile yield strength of 15 MPa or more and 25 MPa or less in the above four specific directions (e, f, g, h). In this case, even when heat treatment for promoting the curing of the adhesive is performed in a state of being wound around the core, generation of wrinkles can be further suppressed and the appearance quality of the packaging material 1 is further improved. Can be made. If the tensile yield strength in at least one of the four specific directions (e, f, g, h) exceeds 25 MPa, it is not preferable because the thermoplastic resin film 3 becomes brittle and impact resistance decreases.

Further, the tensile yield strength of the thermoplastic resin film in the film extrusion direction e is “V” (MPa), the tensile yield strength in the direction f perpendicular to the film extrusion direction is “W” (MPa), The tensile yield strength in the direction g of 45 ° diagonally to the film extrusion direction is “X” (MPa), and the tensile yield strength in the direction h of 45 ° diagonally to the film extrusion direction is “Y” (MPa). )
W / V ≧ 0.85
X / V ≧ 0.88
Y / V ≧ 0.88
It is preferable to use the thermoplastic resin film 3 that satisfies the above three relational expressions. In this case, even if heat treatment for promoting the curing of the adhesive is performed in a state wound on the core, generation of wrinkles can be further suppressed, and the appearance quality of the packaging material 1 can be further improved. This can be further improved.

  For example, a thermoplastic resin film having a tensile yield strength of 15 MPa or more in the four specific directions (e, f, g, h) may be produced by forming (depositing) a thermoplastic resin film by extrusion. It can manufacture by performing an annealing process (heat processing for residual stress elimination) at 65 to 90 degreeC with respect to the thermoplastic resin film after a film | membrane. In addition, the said manufacturing method is only what showed the example, and the thermoplastic resin film used by this invention is not specifically limited to what is obtained with the said manufacturing method.

  There is no restriction | limiting in particular in the kind of resin which comprises the said thermoplastic resin film layer 3. FIG. That is, any kind of resin may be used as long as it is a thermoplastic resin film having a tensile yield strength in the above four specific directions (e, f, g, h) of 15 MPa or more and can impart heat seal performance. It may be of a type.

  The thermoplastic resin film layer 3 is not particularly limited, but is preferably an unstretched thermoplastic resin film layer. The thermoplastic resin unstretched film layer 3 is not particularly limited, but at least one olefin type selected from the group consisting of polyethylene, polypropylene, olefin copolymers, acid-modified products thereof, and ionomers. It is preferably composed of an unstretched film made of a resin.

  Among them, the polypropylene constituting the thermoplastic resin film layer 3 is selected from the group consisting of a mixture of homopolypropylene and a thermoplastic elastomer (for example, ethylene-propylene copolymer rubber), random copolymer polypropylene, and block copolymer polypropylene. It is preferable to use one or more resins. Moreover, as polyethylene which comprises the said thermoplastic resin film layer 3, it is preferable to use a high density polyethylene and / or a linear low density polyethylene.

  The MFR (melt flow rate) of the homopolypropylene constituting the thermoplastic resin film layer 3 is preferably in the range of 0.5 g / 10 min to 20 g / 10 min. The melting point of the homopolypropylene is preferably in the range of 155 ° C to 175 ° C. These MFR and melting point can be controlled by adjusting the molecular weight and the like of homopolypropylene.

  The ethylene content of the random copolymer polypropylene (ethylene-propylene random copolymer resin) constituting the thermoplastic resin film layer 3 is preferably in the range of 1% by mass to 10% by mass. By being 1 mass% or more, the heat seal strength of the packaging material 1 can be further improved, and by being 10 mass% or less, sufficient heat resistance can be secured. The melting point of the random copolymer polypropylene (ethylene-propylene random copolymer resin) is preferably in the range of 135 ° C to 165 ° C. Sufficient heat resistance can be secured when the temperature is 135 ° C. or higher, and the heat seal strength of the packaging material 1 can be further improved when the temperature is 165 ° C. or lower. Further, the MFR (melt flow rate) of the random copolymer polypropylene (ethylene-propylene random copolymer resin) is preferably in the range of 0.5 g / 10 min to 20 g / 10 min. When the MFR is 0.5 g / 10 min or more, good moldability can be secured, and when the MFR is 20 g / 10 min or less, the heat seal strength of the packaging material 1 can be further improved. Among them, the MFR (melt flow rate) of the random copolymer polypropylene (ethylene-propylene random copolymer resin) is more preferably 0.5 g / 10 min to 10 g / 10 min, and further 2 g / 10 min to 7 g. Particularly preferred is / 10 minutes. The MFR and melting point of the random copolymer polypropylene can be controlled by adjusting the molecular weight of the random copolymer polypropylene.

  The ethylene content of the block copolymerized polypropylene (ethylene-propylene block copolymer resin) constituting the thermoplastic resin film layer 3 is preferably in the range of 10% by mass to 20% by mass. When the ethylene content is 10% by mass or more, impact resistance can be imparted to the film, and when the ethylene content is 20% by mass or less, heat resistance can be improved and blocking can be prevented. The melting point of the block copolymerized polypropylene (ethylene-propylene block copolymer resin) is preferably in the range of 155 ° C to 170 ° C. The MFR (melt flow rate) of the block copolymerized polypropylene (ethylene-propylene block copolymer resin) is preferably in the range of 0.5 g / 10 min to 20 g / 10 min. The MFR and melting point of the block copolymerized polypropylene can be controlled by adjusting the molecular weight of the block copolymerized polypropylene.

  The MFR is a melt flow rate measured under conditions of a temperature of 230 ° C. and a load of 2.16 kg in accordance with JIS K7210-1999.

  The melting point is measured in accordance with JIS K7121-2012 using a differential scanning calorimetry (DSC method) by raising the temperature range from 50 ° C. to 200 ° C. at a rate of 10 ° C./min. This is the melting point required.

  Thus, the thermoplastic resin film layer 3 contains one or more polymers selected from the group consisting of homopolypropylene, block copolymerized polypropylene, random copolymerized polypropylene, and ethylene-propylene copolymer rubber (EPR). It is preferable that the structure includes at least one layer (that is, a single-layer structure or a multi-layer structure). When such a configuration is adopted, sufficient sealing strength can be ensured, and generation of wrinkles can be more sufficiently suppressed even when the aging process is performed while being wound around the core.

  The thermoplastic resin film 3 is a laminated film (3 in which covering layers 32 and 32 containing random copolymer polypropylene are laminated and integrated on both surfaces of an intermediate layer 31 containing block copolymer polypropylene. A layer laminated film) is preferred (see FIG. 3). In this case, since the intermediate layer contains block copolymer polypropylene, sufficient impact strength and sufficient piercing strength can be obtained, and a coating layer containing random copolymer polypropylene is laminated on both sides of the intermediate layer. Therefore, sufficient seal strength can be secured. Among them, the thermoplastic resin film 3 is a laminated film (three-layer laminated film) in which covering layers 32 and 32 made of random copolymerized polypropylene are laminated and integrated on both surfaces of an intermediate layer 31 made of block copolymerized polypropylene. Is particularly preferred (see FIG. 3).

  The thermoplastic resin film 3 is formed by laminating coating layers 32 and 32 containing random copolymerized polypropylene on both surfaces of an intermediate layer 31 containing homopolypropylene and ethylene-propylene copolymer rubber (EPR). An integrated laminated film (3-layer laminated film) is preferred (see FIG. 3). In this case, since the intermediate layer 31 contains homopolypropylene having a high melting point, it is possible to sufficiently ensure the thickness after sealing (wall thickness of the inner layer) necessary to obtain sufficient insulation, Since the covering layers 32 and 32 containing random copolymer polypropylene are laminated and integrated on both surfaces of the intermediate layer 31, sufficient sealing strength can be ensured. Furthermore, since the intermediate layer contains ethylene-propylene copolymer rubber, sufficient impact strength and sufficient piercing strength can be obtained. Among them, the thermoplastic resin film 3 is a laminated film (three layers) in which covering layers 32 and 32 made of random copolymer polypropylene are laminated and integrated on both surfaces of an intermediate layer 31 made of homopolypropylene and ethylene-propylene copolymer rubber. A laminated film) is particularly preferred (see FIG. 3).

  The thickness (in the case of multiple layers) T of the thermoplastic resin film layer 3 is preferably set to 20 μm to 80 μm (see FIGS. 1 and 3). When the thickness is 20 μm or more, pinholes can be sufficiently prevented from being generated, and by setting the thickness to 80 μm or less, the amount of resin used can be reduced, and the cost can be reduced. Especially, it is especially preferable that the thickness T of the thermoplastic resin film layer 3 is set to 30 μm to 50 μm. The thermoplastic resin film layer 3 may be a single layer or a multilayer.

  The heat-resistant resin layer (outer layer) 2 is not particularly limited, and examples thereof include polyamide films such as nylon films, polyester films, and the like, and these stretched films are preferably used. Among them, the heat-resistant resin layer 2 includes a biaxially stretched polyamide film such as a biaxially stretched nylon film, a biaxially stretched polybutylene terephthalate (PBT) film, a biaxially stretched polyethylene terephthalate (PET) film or a biaxially stretched polyethylene film. It is particularly preferable to use a phthalate (PEN) film. The nylon film is not particularly limited, and examples thereof include 6 nylon film, 6,6 nylon film, MXD nylon film, and the like. The heat-resistant resin layer 2 may be formed as a single layer, or may be formed as a multilayer composed of a polyester film / polyamide film (such as a multilayer composed of PET film / nylon film). Also good.

  The heat-resistant resin layer 2 preferably has a thickness of 12 μm to 50 μm. When using a polyester film, the thickness is preferably 12 μm to 50 μm, and when using a nylon film, the thickness is preferably 15 μm to 50 μm. By setting it above the preferred lower limit value, it is possible to ensure sufficient strength as the packaging material 1, and by setting it below the preferred upper limit value, it is possible to reduce the stress at the time of stretch molding or draw molding and improve the moldability. be able to.

  The metal foil layer 4 plays a role of providing the packaging material 1 with a gas barrier property that prevents oxygen and moisture from entering. Although it does not specifically limit as said metal foil layer 4, For example, aluminum foil, copper foil, etc. are mentioned, Aluminum foil is generally used. The thickness of the metal foil layer 4 is preferably 20 μm to 100 μm. When it is 20 μm or more, it can prevent the occurrence of pinholes during rolling when manufacturing a metal foil, and when it is 100 μm or less, it can reduce the stress at the time of stretch forming or draw forming and improve the formability. it can.

The metal foil layer 4 is preferably subjected to chemical conversion treatment on at least the inner surface 4a (the surface on the second adhesive layer 6 side). By such chemical conversion treatment, corrosion of the surface of the metal foil due to the contents (battery electrolyte, food, medicine, etc.) can be sufficiently prevented. For example, the metal foil is subjected to chemical conversion treatment by the following treatment. That is, for example, on the surface of the metal foil that has been degreased,
1) Aqueous solution comprising a mixture of phosphoric acid, chromic acid and fluoride metal salt 2) Aqueous solution comprising a mixture of phosphoric acid, chromic acid, fluoride metal salt and non-metal salt 3) Acrylic resin and / or phenolic resin Then, a chemical conversion treatment is performed by applying one of an aqueous solution composed of a mixture of phosphoric acid, chromic acid, and a fluoride metal salt and then drying.

  Although it does not specifically limit as said 1st adhesive bond layer 5, For example, the adhesive bond layer etc. which were formed with the 2 liquid reaction type adhesive agent are mentioned. Examples of the two-component reactive adhesive include a first liquid composed of one or more polyols selected from the group consisting of polyurethane polyols, polyester polyols and polyether polyols, and a second liquid composed of isocyanate. And a two-component reactive adhesive composed of a liquid (curing agent).

  The second adhesive layer 6 is not particularly limited. For example, a polyurethane adhesive, an acrylic adhesive, an epoxy adhesive, a polyolefin adhesive, an elastomer adhesive, and a fluorine adhesive. For example, an adhesive layer formed by the above method may be used. Among these, acrylic adhesives and polyolefin adhesives are preferably used. In this case, the electrolytic solution resistance and water vapor barrier property of the packaging material 1 can be improved.

  In addition, in the said embodiment, although the structure which provided the 1st adhesive bond layer 5 and the 2nd adhesive bond layer 6 is employ | adopted, these both layers 5 and 6 are not an indispensable structural layer, These are not included. It is also possible to adopt a configuration that is not provided.

  A molded case (battery case or the like) can be obtained by molding the packaging material 1 of the present invention (deep drawing molding, stretch molding or the like). In addition, the packaging material 1 of this invention can also be used as it is, without using for shaping | molding.

  One embodiment of a battery configured using the packaging material 1 of the present invention is shown in FIG. The battery 20 is a lithium ion secondary battery.

  The battery 20 includes an electrolyte 21, a tab lead 22, the planar packaging material 1 that is not used for molding, and a molding case 11 having an accommodation recess obtained by molding the packaging material 1 ( (See FIG. 4).

  A part of the electrolyte 21 and the tab lead 22 is accommodated in the accommodating recess 11 b of the molding case 11, the planar packaging material 1 is disposed on the molding case 11, and a peripheral portion of the packaging material 1 The battery 20 is configured by joining and sealing the sealing peripheral portion 11 a of the molded case 11. The leading end of the tab lead 22 is led out to the outside (see FIG. 4).

  Next, specific examples of the present invention will be described, but the present invention is not particularly limited to these examples.

<Example 1>
By co-extrusion molding, a three-layer laminated film of 4 μm thick random copolymerized polypropylene 32/32 μm thick block copolymerized polypropylene 31/4 μm thick random copolymerized polypropylene 32 was obtained. Next, an unstretched thermoplastic resin film (thermoplastic resin layer) 3 having a thickness of 40 μm was obtained by subjecting the three-layer laminated film after film formation to an annealing treatment at 70 ° C. for 48 hours (FIG. 3). reference). The unstretched thermoplastic resin film 3 having a thickness of 40 μm thus obtained has a tensile yield strength in the MD direction of 17.6 MPa, a tensile yield strength in the TD direction of 15.5 MPa, and a tensile yield strength in the 45 ° right oblique direction of 16.1 MPa. The tensile yield strength in the direction of 45 ° to the left was 16.3 MPa (see Table 1).

  The random copolymer polypropylene (ethylene-propylene random copolymer resin) had an ethylene content of 4% by mass, an MFR of 7.5 g / 10 min, and a melting point of 140 ° C. The block copolymerized polypropylene (ethylene-propylene block copolymer resin) had an ethylene content of 20% by mass, an MFR of 2 g / 10 min, and a melting point of 160 ° C.

Further, a chemical conversion treatment solution composed of polyacrylic acid, a trivalent chromium compound, water, and alcohol is applied to both surfaces of a 40 μm thick aluminum foil 4 and dried at 180 ° C., and the chromium adhesion amount is 10 mg / m ^2. It was made to become.

  Next, a 25 μm thick biaxially stretched nylon film (heat resistant resin layer) 2 is bonded to one surface of the chemical conversion treated aluminum foil 4 via a polyester polyurethane adhesive 5, and then the aluminum foil 4 After the unstretched thermoplastic resin film (thermoplastic resin layer) 3 having a thickness of 40 μm was bonded to the other surface via the polyacryl adhesive 6, the laminate was wound around the core many times, The packaging material 1 shown in FIG. 1 was obtained by performing the aging process at 40 degreeC for acceleration | stimulation of hardening of an adhesive agent for 200 hours in this winding state.

<Example 2>
A packaging material 1 shown in FIG. 1 was obtained in the same manner as in Example 1 except that the temperature of the annealing treatment was set to 80 ° C. instead of 70 ° C. Since the annealing treatment temperature was changed from 70 ° C. to 80 ° C., the unstretched thermoplastic resin film 3 having a thickness of 40 μm had a tensile yield strength in the MD direction of 19.4 MPa and a tensile yield strength in the TD direction of 16 The tensile yield strength in the diagonal direction to the right and 45 ° was 17.2 MPa, and the tensile yield strength in the 45 ° direction to the left was 17.3 MPa (see Table 1).

<Example 3>
A packaging material 1 shown in FIG. 1 was obtained in the same manner as in Example 1 except that the temperature of the annealing treatment was set to 100 ° C. instead of 70 ° C. Since the annealing temperature was changed from 70 ° C. to 100 ° C., the unstretched thermoplastic resin film 3 having a thickness of 40 μm had a tensile yield strength in the MD direction of 24.4 MPa and a tensile yield strength in the TD direction of 21. The tensile yield strength in the right diagonal direction of 45 ° was 22.4 MPa, and the tensile yield strength in the left diagonal direction of 45 ° was 22.6 MPa (see Table 1).

<Example 4>
As a resin constituting the intermediate layer of the three-layer laminated film, a mixed resin (a mixed resin having a composition of 70% by mass of homopolypropylene and 30% by mass of ethylene-propylene copolymer rubber) was used in place of the block copolymerized polypropylene. In the same manner as in Example 1, the packaging material 1 shown in FIG. 1 was obtained. “Tuffmer A” manufactured by Mitsui Chemicals was used as the ethylene-propylene copolymer rubber. The obtained unstretched thermoplastic resin film 3 having a thickness of 40 μm has a tensile yield strength in the MD direction of 17.0 MPa, a tensile yield strength in the TD direction of 15.1 MPa, and a tensile yield strength in the 45 ° right diagonal direction of 16 The tensile yield strength in the left oblique direction of 45 ° was 16.1 MPa (see Table 1). The mixed resin had an MFR of 2.5 g / 10 min and a melting point of 163 ° C.

<Comparative Example 1>
A packaging material was obtained in the same manner as in Example 1 except that the temperature of the annealing treatment was set to 30 ° C. instead of 70 ° C. Since the annealing treatment temperature was changed from 70 ° C. to 30 ° C., the resulting 40 μm-thick unstretched thermoplastic resin film 3 had a tensile yield strength in the MD direction of 14.2 MPa and a tensile yield strength in the TD direction of 12 The tensile yield strength in the direction of .5 MPa and 45 ° to the right was 13.2 MPa, and the tensile yield strength in the direction of 45 ° to the left was 13.4 MPa (see Table 1).

<Comparative example 2>
A packaging material was obtained in the same manner as in Example 1 except that the temperature of the annealing treatment was set to 40 ° C. instead of 70 ° C. Since the annealing treatment temperature was changed from 70 ° C. to 40 ° C., the unstretched thermoplastic resin film 3 having a thickness of 40 μm had a tensile yield strength in the MD direction of 14.7 MPa and a tensile yield strength in the TD direction of 14 .3 MPa, the tensile yield strength in the 45 ° right oblique direction was 14.4 MPa, and the tensile yield strength in the 45 ° oblique left direction was 14.2 MPa (see Table 1).

<Comparative Example 3>
A packaging material was obtained in the same manner as in Example 1 except that the temperature of the annealing treatment was set to 50 ° C. instead of 70 ° C. Since the annealing treatment temperature was changed from 70 ° C. to 50 ° C., the unstretched thermoplastic resin film 3 having a thickness of 40 μm had a tensile yield strength in the MD direction of 16.0 MPa and a tensile yield strength in the TD direction of 12 The tensile yield strength in the direction of .8 MPa and 45 ° to the right was 15.9 MPa, and the tensile yield strength in the direction of 45 ° to the left was 15.5 MPa (see Table 1).

<Comparative example 4>
A packaging material was obtained in the same manner as in Example 1 except that the temperature of the annealing treatment was set to 60 ° C. instead of 70 ° C. Since the annealing treatment temperature was changed from 70 ° C. to 60 ° C., the unstretched thermoplastic resin film 3 having a thickness of 40 μm had a tensile yield strength in the MD direction of 17.5 MPa and a tensile yield strength in the TD direction of 14 The tensile yield strength in the direction of .2 MPa and 45 ° to the right was 14.5 MPa, and the tensile yield strength in the direction of 45 ° to the left was 13.9 MPa (see Table 1).

  In addition, the tensile yield strength of the unstretched thermoplastic resin film (thickness 40 μm) used to prepare the packaging materials of Examples 1 to 3 and Comparative Examples 1 to 4 was measured as follows. (Tensile yield strength).

<Measurement method of tensile yield strength>
In accordance with JIS K7127-1999 (plastic film tensile test method), a type 2 test piece (length of 150 mm or more) is prepared for an unstretched thermoplastic resin film (thickness of 40 μm). A tensile test was performed under the conditions of a distance of 50 mm and a tensile speed of 300 mm / min to obtain a tensile yield strength (tensile yield strength). The load at the yield point on the SS curve is the tensile yield strength.

  Each packaging material obtained as described above was evaluated based on the following evaluation method. The results are shown in Table 1.

<Evaluation method for preventing wrinkles>
When the packaging material 1 that has been wound on the core through the aging treatment is rewound onto another core, the presence or absence of wrinkles in the packaging material 1 and the state thereof are visually examined, and based on the following criteria: And evaluated.
(Criteria)
“◎”: No wrinkle was observed, or even if wrinkles were present, the length of one wrinkle was less than 20 mm. “◯”: Wrinkles were recognized, but the length of one wrinkle was all 20 mm. “×” in a range of ˜100 mm: wrinkles are recognized, and the length of one wrinkle exceeds 100 mm accounts for half, wrinkles are remarkable, and the appearance quality is inferior.

<Measurement method of seal strength>
The packaging material 1 was cut out to obtain two strip-shaped test pieces each having a size of 15 mm width × 200 mm length. After the two test pieces were overlapped so that the inner layers 3 were in contact with each other, the inner layers 3 were heat-sealed with a bar sealer set at 200 ° C.

  Thereafter, the two test pieces that were sealed and bonded were peeled 180 degrees at an initial chuck-to-chuck distance of 100 mm and a tensile speed of 300 mm / min in accordance with JIS K7127-1999. ) Was measured. The seal strength per 15 mm width was determined to be 70 MPa or more.

  As is clear from Table 1, the packaging materials of Examples 1 to 4 of the present invention are subjected to heat treatment (aging treatment) for promoting the curing of the adhesive while being wound around the core. There was almost no generation | occurrence | production, and it was excellent in the external appearance quality, and sufficient sealing strength was also obtained.

  On the other hand, in the packaging materials of Comparative Examples 1 to 4 deviating from the specified range of the present invention, wrinkles were conspicuously generated by the heat treatment (aging treatment) in a state of being wound around the core.

  The packaging material according to the present invention is suitably used as a battery case for notebook personal computers, mobile phones, in-vehicle use, stationary lithium ion polymer secondary batteries, etc. However, it is not particularly limited to these uses. Among these, it is particularly suitable for battery cases.

1 ... Packaging material 2 ... Heat-resistant resin layer (outer layer)
3 ... Thermoplastic resin film layer (inner layer)
4 ... Metal foil layer 11 ... Molding case 31 ... Intermediate layer 32 ... Coating layer

Claims (8)

A packaging material comprising a heat-resistant resin layer as an outer layer, a thermoplastic resin film layer as an inner layer, and a metal foil layer disposed between both layers,
The MFR of the thermoplastic resin is in the range of 0.5 g / 10 min to 20 g / 10 min;
As the thermoplastic resin film,
The tensile yield strength in the direction of film extrusion is 15 MPa or more, the tensile yield strength in the direction orthogonal to the film extrusion direction is 15.5 MPa or more, and the tensile yield strength in the direction of 45 ° diagonally to the film extrusion direction is A packaging material characterized in that a thermoplastic resin film having a tensile yield strength of 15 MPa or more in a direction obliquely 45 degrees to the left with respect to the film extrusion direction is 15 MPa or more. As the thermoplastic resin film,
Tensile yield strength in the direction of film extrusion is 15 MPa to 25 MPa, tensile yield strength in the direction orthogonal to the film extrusion direction is 15.5 MPa to 25 MPa, and tensile yield is 45 ° diagonally to the film extrusion direction. The packaging material according to claim 1, wherein a thermoplastic resin film having a strength of 15 MPa to 25 MPa and a tensile yield strength in a direction of 45 ° obliquely to the left with respect to the film extrusion direction is 15 MPa to 25 MPa. The tensile yield strength in the film extrusion direction of the thermoplastic resin film is set to “V”, the tensile yield strength in the direction orthogonal to the film extrusion direction is set to “W”, and the right angle is 45 degrees with respect to the film extrusion direction. When the tensile yield strength in the direction is “X” and the tensile yield strength in the direction 45 ° to the left with respect to the film extrusion direction is “Y”, the following three relational expressions are satisfied: The packaging material according to claim 1 or 2.
W / V ≧ 0.85
X / V ≧ 0.88
Y / V ≧ 0.88   The thermoplastic resin film layer has a homopolypropylene having an MFR of 0.5 g / 10 min to 20 g / 10 min, a block copolymerized polypropylene having an MFR of 0.5 g / 10 min to 20 g / 10 min, and an MFR of 0.1. 4. The structure according to claim 1, comprising at least one layer containing one or two or more polymers selected from the group consisting of 5 g / 10 min to 20 g / 10 min random copolymer polypropylene. The packaging material according to claim 1.   The thermoplastic resin film layer has an MFR of 0.5 g / 10 min to 20 g / 10 on both surfaces of an intermediate layer containing a block copolymerized polypropylene having an MFR of 0.5 g / 10 min to 20 g / 10 min. The packaging material according to any one of claims 1 to 3, which is a laminated film in which a coating layer containing random copolymerized polypropylene is laminated and integrated.   The thermoplastic resin film layer has an MFR of 0.5 g / 10 on both sides of an intermediate layer comprising ethylene-propylene copolymer rubber and homopolypropylene having an MFR of 0.5 g / 10 min to 20 g / 10 min. The packaging material according to any one of claims 1 to 3, which is a laminated film in which a coating layer containing a random copolymerized polypropylene of minutes to 20 g / 10 minutes is laminated and integrated.   A molded case formed by deep-drawing or stretch-molding the packaging material according to claim 1.   The molded case according to claim 7, which is used as a battery case.

Images