JP6936044B2 - Laminate material - Google Patents

Description

The present invention relates to a laminate material used for a battery exterior and a packaging material for foods and pharmaceuticals.

Batteries such as storage batteries for mobile communication terminal devices, in-vehicle storage batteries, storage batteries for regenerative energy recovery, capacitors, and all-solid-state batteries are becoming smaller and lighter, and resin films are attached to both sides of the metal layer as a barrier layer. A combined laminate exterior is used. As the laminate material, a nylon 6 (PA6) film having higher heat resistance and better moldability than the sealant layer is used for the base material layer on the outside, as opposed to the sealant layer on the inside of the exterior body which is heat-sealed. It was common to be done.

In addition, since the exterior body used in a harsh environment such as an in-vehicle battery is required to have high water resistance and heat resistance, a polyethylene terephthalate (PET) film having higher water resistance and heat resistance than PA6 film as a base material layer. Was considered to be used. However, when the PET film is used for the base material layer, the moldability is inferior to that when the PA6 film is used, so that the material of the exterior body to be deep-drawn is not satisfactory.

Therefore, as the base material layer, a multilayer film in which polyethylene terephthalate (polyester resin) having good water resistance (and heat resistance) and nylon 6 (polyamide resin) having good moldability are laminated by coextrusion and biaxially stretched is used. Was proposed (see Patent Documents 1 and 2). It has also been proposed to use a base material layer in which a polybutylene terephthalate resin film having intermediate characteristics between PA6 and PET is laminated as the base material layer (Patent Document 3).

JP-A-2015-156403 Japanese Unexamined Patent Publication No. 2016-62805 Japanese Unexamined Patent Publication No. 2016-104565

The laminating material described in Patent Documents 1 to 3 uses a coextruded film of two or more kinds of resins having different properties, or a film using a resin having intermediate properties between the two kinds of resins, and further with the film. Water resistance was improved by laminating another film. However, there are advantages and disadvantages to the characteristics of the resin, and the battery exterior used in various environments is required to be excellent in all aspects such as moldability, solvent resistance, water resistance, and heat resistance. Improvement is required. On the other hand, in order to reduce the thickness and weight of the battery, it is also required to provide the above characteristics without increasing the thickness of the laminating material.

In view of the above-mentioned technical background, the present invention provides a laminate material having moldability, water resistance, and heat resistance, an exterior material for a battery using this laminate material, and a battery.

That is, the present invention has the configurations described in the following [1] to [6].

[1] A laminated material in which a base material layer, a barrier layer, and a sealant layer are sequentially bonded.
A laminating material, wherein the base material layer is composed of a biaxially stretched multilayer film in which a layer containing at least two types of polyester resin layers is directly laminated.

[2] The biaxially stretched multilayer film includes at least one polyethylene terephthalate (PET) layer and at least one polybutylene terephthalate (PBT) layer, and the PET layer and the PBT layer are laminated adjacent to each other. The laminating material according to item 1 above.

[3] The laminating material according to item 2 above, wherein the biaxially stretched multilayer film is composed of two layers, the PET layer and the PBT layer, and the PBT layer is bonded in a direction facing the barrier layer.

[4] The laminating material according to item 3 above, wherein the PET layer is thinner than the PBT layer.

[5] An exterior body for a battery, characterized in that a storage space for a battery body is formed by facing the sealant layers of the laminate according to any one of the above items 1 to 4 so as to face each other.

[6] A battery comprising the battery exterior body described in item 5 above and a battery body housed in the exterior body.

Since the laminating material according to the above [1] is a biaxially stretched multilayer film in which the base material layer contains at least two types of polyester-based resin layers, it has the advantages of each of the two polyester-based resins. Moreover, since the biaxially stretched multilayer film is directly laminated without using an adhesive, the thickness of the layer is suppressed, and since both are composed of polyester-based resin, delamination that may occur between interfaces. Can be suppressed.

The laminate material described in [2] above is excellent in water resistance and heat resistance because the biaxially stretched multilayer film constituting the base material layer contains a PET layer, and is simultaneously molded because it contains a PBT layer. It is also excellent in sex.

The laminate material described in [3] above is more excellent in water resistance and heat resistance because the PBT layer of the biaxially stretched multilayer film faces the barrier layer and the PET layer is on the outside.

The thickness of the laminating material according to [4] can be reduced as much as possible while maintaining moldability, water resistance, and heat resistance by the ratio of the thickness of the PET layer and the PBT-based layer.

Since the battery exterior body according to the above [5] is composed of the laminate material described in the above [1] to [4], the above effect can be obtained.

Since the exterior body of the battery described in the above [6] is composed of the battery exterior body described in the above [5], the above effect can be obtained.

It is sectional drawing of the laminated lumber of one Embodiment of this invention.

In the laminate 1 of FIG. 1, the base material layer 13 is laminated on one surface of the barrier layer 11 via the first adhesive layer 12, and the second adhesive layer 14 is laminated on the other surface of the barrier layer 11. The sealant layer 15 is laminated with the sealant layer 15, and the resin layer is laminated on both surfaces of the barrier layer 11.

As the resin constituting the base material layer 13, a resin that does not melt at the heat sealing temperature when the laminating material 1 is heat-sealed is used. Specifically, it is preferable to use a resin having a melting point higher than the melting point of the resin constituting the sealant layer 15, and it is more preferable to use a resin having a melting point higher than 20 ° C. The biaxially stretched multilayer film used as the base material layer in the present invention contains at least two types of polyester resin layers, and for example, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN) and the like are used. can. These polyesters satisfy the above melting point conditions.

Further, by using two kinds of polyester resins, the advantages of each resin can be combined. For example, polyethylene terephthalate (PET), which is generally used as a polyester resin, has higher heat resistance and water resistance than nylon 6, which is generally used as a polyamide resin, but nylon 6 is superior in moldability. ing. Then, heat resistance, water resistance and moldability can be improved by using a multilayer film in which one of at least two types of polyester resin layers is formed of a polyester resin having high moldability.

The base material layer 13 is a layer on the outside of a container such as a battery case, and has a two-layer structure composed of an outer first layer, 13a, and a second layer 13b facing the barrier layer 11. In the base material layer 13, a film formed by directly laminating two different types of polyesters in which the first layer 13a and the second layer 13b are directly laminated without using an adhesive is biaxially stretched to orient the molecules. It is a multilayer film. Since the multilayer film is made of the same polyester resin, the occurrence of delamination and the like that may occur between the interfaces is suppressed. Such a biaxially stretched multilayer film is laminated without using an adhesive by coextruding by a T-die method, an inflation method, or the like, and is biaxially stretched by a tubular method, a tenter method, or the like after coextrusion. Can be made. By using a biaxially stretched multilayer film laminated by coextrusion without using an adhesive as the base material layer 13, the thickness of the film can be minimized. In addition, since it is laminated and integrated at the same time as extrusion by coextrusion and biaxially stretched on the integrated multilayer film, the biaxially stretched multilayer film can be formed in fewer steps than laminating a single-layer biaxially stretched film with an adhesive. Can be made.

The laminate material of the present invention is required to be a biaxially stretched multilayer film having two or more layers including at least two types of polyester resin layers as a base material layer, and has one or more PET layers and one PBT layer. It preferably contains more than one layer, and a biaxially stretched multilayer film having a two-layer structure consisting of a PET layer and a PBT layer is preferable. Polyethylene terephthalate has excellent water resistance and heat resistance, while polybutylene terephthalate has excellent moldability. By including these two types of polyester resin layers in two or more layers, the moldability is improved. Water resistance and heat resistance can be provided, and solvent resistance can also be improved. The biaxially stretched multilayer film having a bilayer structure is produced by co-extruding PET and PBT and then biaxially stretching. The PET layer and the PBT layer can be composed of a resin composition to which other resins are added as long as the characteristics of the respective resins are not impaired. For example, PBT can be added to the PET layer, and PET can be added to the PBT layer as well.

When a biaxially stretched multilayer film having a two-layer structure consisting of a PET layer and a PBT layer is used, the PET layer is used as the outer first layer 13a, the PBT layer is used as the second layer 13b on the barrier layer 11 side, and the PBT layer is a barrier. It is preferable to bond them in the direction facing the layer 11, and particularly excellent water resistance and heat resistance can be obtained while maintaining moldability.

Further, when a biaxially stretched multilayer film having a two-layer structure consisting of a PET layer and a PBT layer is attached to the barrier layer 11 with the PET layer on the outside, that is, the first layer 13a in FIG. 1a is the PET layer and the second layer 13b is In the case of the PBT layer, the thickness T2 of the PET layer is preferably the thickness T1 of the base material layer 13, that is, 5% to 50% of the total thickness of the PET layer and the PBT layer. If the thickness T2 of the PET layer is less than 5%, the heat resistance deteriorates, and if it exceeds 50%, the moldability deteriorates. The thickness T1 of the layer 13 can be made as thin as possible. A particularly preferable PET layer thickness T2 is 10% to 45% of T1.

When using a biaxially stretched multilayer film having three or more layers, at least two layers need to be polyester, but the third and subsequent layers are resins other than polyester, for example, a polyamide resin such as nylon 6, and polyethylene. Or a polyolefin resin such as polypropylene can be used. In this case, it is preferable to arrange two types of polyester resin layers on the outside. The total thickness of the base material layer 13 is preferably 10 μm to 80 μm, more preferably 15 μm to 50 μm, regardless of the number of layers and the type of resin.
[Layer other than the base material layer]
The present invention does not limit the material of each layer other than the base material layer, and appropriately selects the material according to the use of the laminating material. The following are examples of preferred materials for battery cases.

The barrier layer 11 is not particularly limited, and examples thereof include a metal foil. Examples of the metal foil include aluminum foil, stainless steel foil, nickel foil, copper foil, titanium foil, clad foils of these metals, and plating foils obtained by plating these metal foils. The thickness of the barrier layer 11 is preferably 5 μm to 150 μm, more preferably 20 μm to 100 μm. When it is 20 μm or more, it is possible to prevent the occurrence of pinholes during rolling when manufacturing a metal foil, and when it is 100 μm or less, the stress during molding such as overhang molding and draw forming can be reduced and the formability is improved. be able to.

When a metal foil is used for the barrier layer, it is preferable that at least the inner surface (the surface on the sealant layer 15 side) is subjected to chemical conversion treatment. By performing such a chemical conversion treatment, it is possible to sufficiently prevent corrosion of the metal foil surface by the contents (electrolyte solution of the battery, etc.). For example, the metal foil is subjected to chemical conversion treatment by performing the following treatment. That is, for example, on the surface of a metal foil that has been degreased,
1) Phosphoric acid and
With chromic acid
An aqueous solution of a mixture containing at least one compound selected from the group consisting of a metal salt of fluoride and a non-metal salt of fluoride 2) Phosphoric acid.
At least one resin selected from the group consisting of acrylic resins, chitosan derivative resins and phenolic resins, and
An aqueous solution of a mixture containing at least one compound selected from the group consisting of chromic acid and a chromium (III) salt 3) phosphoric acid.
At least one resin selected from the group consisting of acrylic resins, chitosan derivative resins and phenolic resins, and
At least one compound selected from the group consisting of chromic acid and chromium (III) salt, and
An aqueous solution of a mixture containing at least one compound selected from the group consisting of a metal salt of fluoride and a non-metal salt of fluoride An aqueous solution of any one of 1) to 3) above is applied and then dried. By doing so, the chemical conversion process is performed.

The conversion coating, chromium coating weight preferably is 0.1mg ^{/ m 2} ~50mg ^/ m 2 as a (per one surface), in particular ^2mg / ^{m 2 ~20mg} / m ² preferred.

The thermoplastic resin constituting the sealant layer 15 is preferably composed of polyethylene, polypropylene, an olefin-based copolymer, an acid-modified product thereof, and an ionomer in terms of chemical resistance and heat-sealing property. Further, examples of the olefin-based copolymer include an ethylene-vinyl acetate copolymer (EVA), an ethylene-acrylic acid copolymer (EAA), and an ethylene-methacrylic acid copolymer (EMAA). Examples of the acid-modified product include maleic anhydride-modified polypropylene and maleic anhydride-modified polyethylene. Further, a part of a polyamide film (for example, nylon 12) or the like can be used as long as the melting point is lower than that of the base material layer. The thickness is preferably 15 μm to 150 μm, more preferably 30 μm to 100 μm. The sealant layer 15 is preferably formed of a heat-sealing resin unstretched film layer, and the sealant layer 15 may be a single layer or a plurality of layers.

As the first adhesive 12 on the base material layer 13 side, for example, a two-component curable polyester-urethane resin made of a polyester resin as a main agent and a polyfunctional isocyanate compound as a curing agent, or a polyether-urethane resin may be used. It is preferable to use an adhesive containing the mixture. On the other hand, as the second adhesive 14 on the sealant layer 15 side, for example, a polyurethane adhesive, an acrylic adhesive, an epoxy adhesive, an acid-modified polyolefin adhesive, an elastomer adhesive, a fluorine adhesive, or the like can be used. Examples include the formed adhesive. The thickness (thickness after drying) of the first adhesive 12 and the second adhesive 15 is preferably set to 1 μm to 4 μm, and the laminate material 1 of the present invention is molded (deep drawing molding, overhang molding, etc.). ), A molded case (battery case, etc.) can be obtained. The laminating material 1 of the present invention can be used as it is without being subjected to molding. For example, when used as a battery case, the battery elements (positive electrode, negative electrode, separator, electrolyte) are housed in the recessed portion of the laminate material 1 formed so that the sealant layer 15 side has a concave surface, and tab leads are used from the positive electrode and the negative electrode, respectively. After securing the energized portion from the laminate 1, the sealant portions of another laminate material are arranged so as to face each other, and the defined peripheral edge portion is heat-sealed while degassing, whereby the power storage device can be obtained. One end of the tab lead is derived to the outside.

The use of the laminate material of the present invention is not limited, and it can be widely used for battery exteriors and packaging materials for foods and pharmaceuticals.

A laminated material in which a base material layer was bonded to one surface of the barrier layer and a sealant layer was bonded to the other surface was prepared using base material layers having different layer structures and materials, and their physical characteristics were compared. The layer structure excluding the base material layer is the structure shown in FIG. 1, and the material of the layer excluding the base material layer is common to each example. The common barrier layer 11, sealant layer 15, first adhesive layer 12, and second adhesive layer 14 are as follows.

Barrier layer 11: Soft aluminum foil with a thickness of 40 μm (A8079H specified by JIS H4160)
Sealant layer 15: Unstretched polypropylene film with a thickness of 80 μm First adhesive layer 12: Two-component curable polyester-urethane adhesive Second adhesive layer 14: Two-component curable acid-modified polypropylene adhesive (base material layer) And preparation of laminate material)
Examples 1 , 3, Reference Examples 2 , 4, 5, 6, and Comparative Example 6 are two-layer or three-layer multilayer films, and the outermost layer of the laminated material is the first layer, and the barrier layer 11 side. The second layer and the third layer are used in this order. The material resin of each layer shown in Table 1 was coextruded using a two-layer inflation ring die or a three-layer inflation ring die, and then biaxially stretched by the tuber method to prepare a biaxially stretched multilayer film. .. Table 1 shows the thickness of each layer after biaxial stretching.

Comparative Examples 1 to 3 are single-layer biaxially stretched films made of the resins shown in Table 1.

Then, the prepared base material layer was bonded to one surface of the barrier layer 11 by the dry laminating method, and the sealant layer was bonded to the other surface.

The moldability, water resistance, heat resistance, and solvent resistance of the prepared laminated material were evaluated by the following methods. The evaluation results are shown in Table 1.
(Moldability)
Using a deep drawing molding tool manufactured by Amada Co., Ltd., deep drawing was performed with a length of 55 mm and a width of 35 mm in such a manner that the base material layer side of the laminating material was convex and the sealant layer side was concave. Several moldings were performed at different molding depths, and the obtained molded product was examined for the occurrence of pinholes and cracks by a light transmission method in a dark room, and the maximum molding depth at which pinholes or cracks did not occur was laminated. The maximum molding depth of the material was evaluated according to the following criteria.

◯… Maximum molding depth is 5 mm or more Δ… Maximum molding depth is 3.5 mm or more and less than 5 mm ×… Maximum molding depth is less than 3.5 mm (water resistance)
In the same manner as in the moldability test, deep drawing was performed with a length of 55 mm, a width of 35 mm, and a depth of 5 mm. At this time, molding was performed so that the base material layer was on the outside of the molded body, and two molded bodies were produced for each example. The two molded bodies were superposed on each other at the flange portions around the molded portion, and heat-sealed at 170 ° C. for 6 seconds. Next, after immersing the heat-sealed product in hot water at 85 ° C. for 240 hours, the heat-sealed product is taken out and visually observed to check for the presence or absence of delamination (peeling) in the heat-sealed portion and the presence or absence of appearance floating, and the following criteria are used. Evaluated based on.

○… No delamination was observed, and no appearance was observed (passed).
△… Slight delamination rarely occurred, but the appearance did not appear (passed).
×… Delamination occurred and the appearance was also floating (failed).
(Heat-resistant)
The laminated material was cut into strips having a width of 15 mm and a length of 100 mm to form test pieces. Two of the test pieces were prepared, the sealant layers were overlapped with each other facing each other, and the entire surface was heat-sealed to form a heat-sealed portion (heat-sealed portion). The heat seal was performed by using a heat seal device (TP-701-A) manufactured by Tester Sangyo Co., Ltd., and heating the seal pressure at 0.2 MPa (gauge display pressure) at 225 ° C. for 2 seconds on one side. After heat sealing, the surface of the sealed portion was observed and evaluated based on the following criteria.

○… No change (pass)
△… Fine wrinkles occur (pass)
×… Surface whitening or melting part occurs (failure)
(Solvent resistance)
The laminated material was cut into a rectangle having a length of 50 mm and a width of 100 mm to obtain a test piece. _{An electrolytic solution in which 1 mol / L lithium hexafluorophosphate (LiPF 6} ) is mixed with an electrolytic solvent containing ethylene carbonate (EC) and diethyl carbonate (DEC) containing 5000 ppm of water in equal amounts. The mixture was immersed in, and stored statically for 24 hours in an environment of a temperature of 55 ° C. and a humidity of 95% RH. Next, after taking out the test piece and washing it with water, the surface of the base material layer was visually observed to confirm the location where the delamination occurred, and the length of the widest portion in the area where the delamination range was the maximum. Was measured and evaluated based on the following criteria.

○… No change (pass)
△… Delamination occurs only on the end face (pass)
×… Nation occurs as a whole (failure)

From the results in Table 1, it was confirmed that excellent moldability, water resistance, heat resistance, and solvent resistance can be obtained by using a biaxially stretched multilayer film in which two types of polyesters are laminated on the base material layer.

The present invention can be suitably used as a laminating material for the exterior body of a battery.

1 ... Laminate material 11 ... Barrier layer 13 ... Base material layer 13a ... First layer 13b ... Second layer 15 ... Sealant layer T1 ... Total thickness of base material layer T2 ... Thickness of first layer

Claims (3)

It is a laminated material in which a base material layer, a barrier layer, and a sealant layer are sequentially bonded.
The base material layer is composed of two layers in which a polyethylene terephthalate (PET) layer and a polybutylene terephthalate (PBT) layer are laminated, and the PBT layer is bonded in a direction facing the barrier layer, and the thickness of the PET layer is the above. A laminating material characterized by being thinner than the PBT layer. An exterior body for a battery, wherein a storage space for a battery body is formed by facing the sealant layers of the laminate according to claim 1. A battery comprising the battery exterior body according to claim 2 and a battery body housed in the exterior body.

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