JP6936048B2 - 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 for the laminate material, a polyamide film having higher heat resistance and better moldability than the sealant layer is generally 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. Is the target. Further, polyolefin is used for the sealant layer, and the temperature of the seal bar at the time of heat sealing is set according to the melting temperature of the polyolefin.

The polyamide constituting the base material layer has excellent moldability, but the difference in melting point between the sealant layer and the polyolefin is small. For this reason, a compound having a small molecular weight contained in polyamide may precipitate on the surface of the base material layer and adhere to the seal bar, which causes a problem that the sealed product has a poor appearance.

As a method of preventing the resin from adhering to the seal bar, there is a method of coating the surface of the base material layer with a refractory resin such as Teflon (registered trademark) (polytetrafluoroethylene). It has also been proposed to use a two-layer film in which polyester and polyamide, which have a higher melting point than polyamide, are integrated by coextrusion (see Patent Documents 1 and 2).

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

However, there is a problem that the moldability is lowered when the polyamide film is coated with Teflon (registered trademark). Further, the coextruded film of different resins such as polyester and polyamide requires a special adhesive because the bondability between the layers is not good, and the manufacturing cost is higher than that of the coextruded resin of the same type. Moreover, there is a problem that the moldability is lowered as compared with the polyamide single-layer film.

In view of the above-mentioned technical background, the present invention provides a laminated material having both heat resistance and moldability and suppressing an increase in cost as much as possible, and an exterior body for a battery using this laminated material. be.

That is, the present invention has the configurations described in the following [1] to [5].

[1] 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 a biaxially stretched multilayer film in which layers containing at least two types of polyamide layers having different melting points are directly laminated, and the base material layer has a high melting point polyamide layer having the highest melting point on the opposite side of the barrier layer. A laminate material characterized by being bonded to the barrier layer in the direction located in.

[2] The laminating material according to item 1 above, wherein the melting point polyamide layer has a thickness of 0.5 μm to 10 μm.

[3] The laminating material according to item 1 or 2 above, wherein the high melting point polyamide layer is made of a polyamide having an aromatic ring in the main chain, and the other polyamide layer is made of an aliphatic polyamide.

[4] An exterior body for a battery, characterized in that a storage space for a battery body is formed by facing each other of the sealant layers of the laminate material according to any one of the above items 1 to 3.

[5] A battery comprising the battery exterior body described in item 4 above and a battery body housed in the exterior body.

The laminate material according to the above [1] is a biaxially stretched multilayer film in which the base material layer contains at least two types of polyamide layers having different melting points, and since the outer layer is a high melting point polyamide layer, it has high heat resistance and heat. Resin adhesion to the seal bar is prevented during sealing. Further, since the barrier layer side of the base material layer is a polyamide layer having a low melting point, moldability is good. Further, since the biaxially stretched multilayer film constituting the base material layer is a film in which the same type of resin is laminated, the bonding force between the layers is strong and it is difficult to peel off. Therefore, the moldability is good, and the manufacturing cost can be suppressed as compared with the multilayer film of different resins. Further, since the layers are directly laminated without using an adhesive, the thickness of the layers can be suppressed.

According to the laminating material described in [2] above, a sufficient effect of improving heat resistance can be obtained depending on the thickness of the high melting point polyamide layer.

The laminating material according to the above [3] is a combination suitable for obtaining good moldability with other polyamides while ensuring heat resistance by using a high melting point polyamide.

Since the battery exterior body according to the above [4] is composed of the laminate material described in the above [1] to [3], the above effect can be obtained.

Since the exterior body of the battery described in the above [5] is composed of the battery exterior body described in the above [4], 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 13 in the present invention contains at least two kinds of polyamide layers having different melting points, and satisfies the above-mentioned melting point conditions. Then, the base material layer 13 is bonded to the barrier layer 11 in the direction in which the high melting point polyamide layer having the highest melting point is located on the opposite side of the barrier layer 11, and the high melting point polyamide layer becomes the outermost layer of the laminate material. Therefore, it is the high melting point polyamide layer that comes into contact with the seal bar for heat sealing, and protects the polyamide layer on the barrier layer 11 side to obtain high heat resistance and prevents the base material layer 13 from adhering to the seal bar. Will be done. Further, the lower the melting point of the polyamide, the better the moldability, and the better moldability can be obtained by the base material layer 13 containing the polyamide layer having a lower melting point than the high melting point polyamide layer.

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 types of polyamides in which the first layer 13a and the second layer 13b have different melting points are directly laminated without using an adhesive is biaxially stretched to orient the molecules. It is a multilayer film that has been made to grow. In the base material layer 13 having the two-layer structure, the first layer 13a is a high melting point polyamide layer, and the second layer 13b is made of a polyamide having a lower melting point than the first layer 13a. The biaxially stretched multilayer film can be produced by laminating without using an adhesive by coextruding by a T-die method, inflation, or the like, and then biaxially stretching by a tubular method, a tenter method, or the like after coextrusion. By using a biaxially stretched multilayer film laminated by coextrusion as the base material layer 13, the thickness of the film can be minimized. Further, the coextruded film of the same resin has a strong bonding force between layers, delamination is less likely to occur during molding, and good moldability can be obtained. Moreover, since the bonding force between the layers is strong and no adhesive is required, the manufacturing cost can be suppressed as compared with the multilayer film of different resins. Since it is laminated and integrated at the same time as extrusion by coextrusion and biaxially stretched on the integrated multilayer film, a biaxially stretched multilayer film can be produced in fewer steps than laminating a single-layer biaxially stretched film with an adhesive. ..

The polyamide constituting the base material layer 13 may be either a polyamide having an aromatic ring in the main chain or an aliphatic polyamide. Further, it is preferable that the high melting point polyamide layer and the other polyamide layer have a melting point difference of 5 ° C. or more, and even more preferably if there is a melting point difference of 10 ° C. or more. The melting point is the melting temperature defined in JIS K7121 (2012). Table 1 shows polyamides suitable as the base material layer 13 and their melting points. When selecting the material for the high melting point polyamide layer, the glass transition temperature shall be substituted for the melting point for paraamide or its modified product.

As a combination of polyamides having different melting points in the biaxially stretched multilayer film, a polyamide containing an aromatic ring in the main chain, for example, metaxylylenediamine (MXD) is used as the high melting point polyamide, and an aliphatic polyamide is used as the polyamide having a low melting point. The combination used is preferred. More preferably, a combination of a copolymer of m-xylylenediamine and adipic acid (MXD6) and a ring-opening condensate of ε-caprolactam (6-nylon) can be recommended. It is also preferable to use a mixture of MXD6 and 6-nylon as one of the two types of polyamide, and by using such a mixed polyamide, the bonding force with the MXD6 alone or the 6-nylon alone is enhanced and delamination during molding is performed. Can be reduced, and the moldability is improved. When 6-nylon and the mixed polyamide are combined, that is, when the mixed polyamide is a refractory polyamide, the ratio of 6-nylon in the mixed polyamide is preferably 5% to 95% in mole (material amount), particularly 10 % To 70% is preferable, and 10% to 50% is more preferable. On the contrary, when MDX6 and the mixed polyamide are combined, that is, when MXD6 is a refractory polyamide, the MXD6 ratio in the mixed polyamide is preferably 5% to 95% in mole (material amount), particularly 10% to 70%. Is preferable, and 10% to 50% is more preferable. The melting points of the mixed polyamides differ depending on the mixing ratio, and Table 1 shows the melting points of two types of mixed polyamides having different mixing ratios.

The laminate material of the present invention is a biaxially stretched multilayer film in which the base material layer contains at least two types of polyamide layers having different melting points, and also includes a multilayer film composed of three or more layers of polyamide. Further, as referred to in FIG. 1, the total thickness T1 of the base material layer 13 is preferably 15 μm to 50 μm, more preferably 25 μm to 40 μm, regardless of the number of layers. The thickness T2 of the high melting point polyamide layer is preferably 0.5 μm to 10 μm. If the thickness T2 of the high melting point polyamide layer is less than 0.5 μm, the effect of improving heat resistance is small, and if it exceeds 10 μm, the low melting point polyamide layer may become relatively thin and the moldability may be deteriorated. A more preferable thickness of the refractory polyamide layer is 1 μm to 5 μm. Although FIG. 1 shows the base material layer 13 having a two-layer structure, the preferable ranges of the total thickness T1 and the thickness T2 of the high melting point polyamide layer are common even in the base material layers of three or more layers.
[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 15 μm to 150 μm, more preferably 20 μm to 100 μm. When it is 15 μm or more, it is possible to prevent the occurrence of pinholes during rolling when manufacturing a metal foil, and when it is 150 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 20 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.

A molded case (battery case, etc.) can be obtained by molding (deep drawing molding, overhang molding, etc.) the laminate material 1 of the present invention. 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 peripheral 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: Chromate film is formed on both sides of a 40 μm-thick aluminum foil (A8021H material specified by JIS H4160) ^{so that the amount of adhesion is 2 mg / m 2.} Sealant layer 15: Unstretched polypropylene film with a thickness of 40 μm. First Adhesive Layer 12: Two-Liquid Curable Polyester-Urethane Adhesive Second Adhesive Layer 14: Two-Liquid Curable Maleic Acid-Modified Polypropylene Adhesive (Preparation of Base Material Layer and Laminate Material)
Examples 1 , 2, 4, 5 and Reference Example 3 and Comparative Examples 2 and 3 are two-layer multilayer films, the outermost layer of the laminating material is the first layer 13a, and the layer on the barrier layer 11 side is the first layer 13a. The second layer 13b. The material resin of each layer shown in Table 2 was coextruded using a ring die for two-layer inflation, and then biaxially stretched by a tubular method to prepare a biaxially stretched multilayer film. Table 2 shows the thickness of each layer after biaxial stretching.

Comparative Example 1 is a single-layer biaxially stretched film made of the resin shown in Table 2.

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 heat resistance, cost and moldability of the prepared laminated lumber were evaluated by the following methods. The evaluation results are shown in Table 2.
(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 bar with a seal pressure of 0.2 MPa (gauge display pressure) at 210 ° C. for 3 seconds on one side. After heat sealing, the state of adhesion of the base material layer 13 to the seal bar was observed and evaluated based on the following criteria.

◎… The base material layer does not adhere to the seal bar at all (pass)
△… The laminated material is slightly attracted when the seal bar is removed, but it naturally separates due to the weight of the laminated material (pass).
×… The base material layer adheres to the seal bar (failure)
Further, with respect to the heat-sealed product after the above heat resistance test, a strograph (tensile test device, AGS) manufactured by Shimadzu Access Co., Ltd., which is placed in a constant temperature bath at 25 ° C. (room temperature) in accordance with JIS Z0238 (1998). Using -5 kNX), the sealant layers were separated from each other by pulling them at a tensile speed of 100 mm / min at 90 degrees, and the heat seal strength was measured. As a result, it was confirmed that the heat seal strength of all the heat seal products was 30 N / 15 mm width or more, and the heat seal conditions in the above heat resistance test were appropriate.
(cost)
Assuming that the production cost of the laminate material of Comparative Example 1 in which the base material layer is formed of a single layer is 100%, the production cost of another laminate material in which the base material layer is formed of two layers is evaluated, and 120% or less is evaluated. Passed.

⊚: 115% or less (passed)
◯: More than 115% and 120% or less (passed)
×: Over 120% (failed)
(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 7 mm or more Δ… Maximum molding depth is 5 mm or more and less than 7 mm ×… Maximum molding depth is less than 5 mm

From the results in Table 2, excellent heat resistance and moldability can be obtained by using a biaxially stretched multilayer film using a refractory polyamide as the outer layer as the base material layer, and more than using a multilayer film of a dissimilar resin. Also confirmed that the cost can be suppressed.

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 (high melting point polyamide layer)
13b ... Second layer 15 ... Sealant layer T1 ... Total thickness of base material layer T2 ... Thickness of first layer (high melting point polyamide layer)

Claims (4)

A laminating material for battery exteriors, in which a base material layer, a barrier layer made of metal leaf , and a sealant layer are sequentially bonded.
The base material layer is composed of a biaxially stretched multilayer film in which layers containing at least two types of polyamide layers having different melting points are directly laminated, and the base material layer has a high melting point polyamide layer having the highest melting point on the opposite side of the barrier layer. is bonded to the barrier layer in a direction located in,
A laminating material having a total thickness of the base material layer of 15 μm to 50 μm and a thickness of the refractory polyamide layer of 0.5 μm to 10 μm. The laminating material according to claim 1 , wherein the high melting point polyamide layer is made of a polyamide having an aromatic ring in the main chain, and the other polyamide layer is made of an aliphatic polyamide. 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 or 2. A battery comprising the battery exterior body according to claim 3 and a battery body housed in the exterior body.

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