CN111164781B

CN111164781B - Polybutylene terephthalate film, battery packaging material, method for producing battery packaging material, and battery

Info

Publication number: CN111164781B
Application number: CN201880062592.6A
Authority: CN
Inventors: 平木健太; 高萩敦子; 山下力也
Original assignee: Dai Nippon Printing Co Ltd
Current assignee: Dai Nippon Printing Co Ltd
Priority date: 2017-10-11
Filing date: 2018-10-10
Publication date: 2022-07-08
Anticipated expiration: 2038-10-10
Also published as: CN111164781A; JPWO2019074016A1; JP7143854B2; WO2019074016A1

Abstract

The present invention provides a polybutylene terephthalate film used for a substrate layer of a battery packaging material having at least the substrate layer, a barrier layer, and a heat-sealable resin layer in this order, the polybutylene terephthalate film having a difference in heat of fusion Δ H determined by the following method_1－2The absolute value of (A) is 3.0J/g or more. (difference in Heat of fusion Δ H)_1－2Method for obtaining absolute value of (1) based on the provisions of JIS K7122-2012, the heat of fusion H measured at the 1 st time was measured by heating from-50 ℃ to 250 ℃ at a temperature rise rate of 10 ℃/min using a differential scanning calorimeter₁. Then, the heat of fusion H is measured₁Then, the temperature was cooled from 250 ℃ to-50 ℃ at a cooling rate of 10 ℃/min, and then heated from-50 ℃ to 250 ℃ at a heating rate of 10 ℃/min, and the heat of fusion H measured at the 2 nd time was measured₂. The heat quantity H of fusion is calculated₁With heat of fusion H₂Difference in heat of fusion Δ H_1－2Absolute value of (a).

Description

Polybutylene terephthalate film, battery packaging material, method for producing battery packaging material, and battery

Technical Field

The present invention relates to a polybutylene terephthalate film, a battery packaging material, a method for producing a battery packaging material, and a battery.

Background

Various types of batteries have been developed, and among all the batteries, a packaging material is an indispensable member for sealing battery elements such as electrodes and electrolytes. Conventionally, a metal packaging material is often used as a battery package.

On the other hand, with the recent increase in performance of electric vehicles, hybrid electric vehicles, computers, cameras, cellular phones, and the like, batteries are required to have various shapes, and also to be thin and light. However, the metal-made battery packaging materials that are commonly used at present have disadvantages in that it is difficult to follow the diversification of shapes, and weight reduction is limited.

Therefore, in recent years, as a battery packaging material which can be easily processed into various shapes and can be made thin and light, a film-shaped laminate in which a base material/an aluminum alloy foil layer/a heat-sealable resin layer are sequentially laminated has been proposed.

In such a battery packaging material, in general, a battery in which a battery element is housed inside the battery packaging material is obtained by forming a concave portion by cold rolling, disposing a battery element such as an electrode or an electrolyte solution in a space formed by the concave portion, and thermally welding the thermally-weldable resin layers to each other. However, such a film-shaped packaging material has disadvantages that it is thinner than a metal packaging material and that pinholes and cracks are likely to occur during molding. When pinholes or cracks are generated in the battery packaging material, the electrolyte solution penetrates into the aluminum alloy foil layer to form metal precipitates, and as a result, a short circuit may occur.

In the film-shaped battery packaging material, a polyamide film or a polyester film is generally used as the base layer.

Among these, polybutylene terephthalate films have excellent chemical resistance and high mechanical strength. However, the polybutylene terephthalate film has a problem of inferior moldability to the polyamide film. Therefore, there is a problem that it is difficult to use a polybutylene terephthalate film as a base layer of a film-shaped battery packaging material.

For example, patent document 1 describes a biaxially oriented polyester film mainly containing a polybutylene terephthalate resin, and a laminate having excellent moldability, excellent warp resistance and acid resistance, and no interlayer peeling during molding can be obtained by stacking 50 or more layers in the thickness direction of a layer made of polyester a and a layer made of polyester B.

Documents of the prior art

Patent literature

Patent document 1: japanese patent laid-open publication No. 2015-147309

Disclosure of Invention

Technical problem to be solved by the invention

However, even if the moldability of a laminate using polybutylene terephthalate film can be improved by the technique of patent document 1, for example, when 2 kinds of polyester films are laminated to 50 layers to form a base layer of a battery packaging material, the apparatus becomes extremely complicated and the productivity is low, so that it is practically difficult to apply the technique to a battery packaging material.

Under such circumstances, the main object of the present invention is to: provided is a polybutylene terephthalate film which exhibits excellent moldability when used as a base material layer of a packaging material for a battery. Further, the present invention is directed to: a battery packaging material using the polybutylene terephthalate film, a method for producing the battery packaging material, and a battery using the battery packaging material are provided.

Means for solving the technical problem

The present inventors have conducted intensive studies to solve the above-mentioned problems. As a result, they have found that excellent moldability can be imparted to a battery packaging material by using a polybutylene terephthalate film as a base material layer of a battery packaging material comprising at least a base material layer, a barrier layer and a heat-sealable resin layer in this order, and that the polybutylene terephthalate film can be used for the base material layer of the battery packaging materialHeat of fusion H of butanediol terephthalate film₁And heat of fusion H₂Difference in heat of fusion Δ H_1－2Has an absolute value of 3.0J/g or more, and the above-mentioned quantity of heat of fusion H₁Is the heat of fusion measured 1 st time by heating from-50 ℃ to 250 ℃ at a temperature rise rate of 10 ℃/min by using a differential scanning calorimeter, the heat of fusion H being defined in JIS K7122-2012₂The heat of fusion H is measured₁Then, the sample was cooled from 250 ℃ to-50 ℃ at a cooling rate of 10 ℃/min, and then heated from-50 ℃ to 250 ℃ at a heating rate of 10 ℃/min, and the heat of fusion was measured 2 nd time. The present invention has been completed based on these findings and further research and study.

That is, the present invention provides the following embodiments.

Item 1. a polybutylene terephthalate film, wherein,

the polybutylene terephthalate film is used for a packaging material for a battery, the packaging material comprising at least a substrate layer, a barrier layer and a heat-sealable resin layer in this order, and the polybutylene terephthalate film has a difference in heat of fusion Δ H determined by the following method_1－2The absolute value of (A) is 3.0J/g or more.

(difference in Heat of fusion Δ H)_1－2Method for obtaining absolute value of (1)

The heat of fusion H measured at the 1 st time was measured by heating from-50 ℃ to 250 ℃ at a temperature rise rate of 10 ℃/min using a differential scanning calorimeter in accordance with the provisions of JIS K7122-2012₁. Then, the heat of fusion H is measured₁Then, the temperature was cooled from 250 ℃ to-50 ℃ at a cooling rate of 10 ℃/min, and then heated from-50 ℃ to 250 ℃ at a heating rate of 10 ℃/min, and the heat of fusion H measured at the 2 nd time was measured₂. The heat quantity H of fusion is calculated₁With heat of fusion H₂Difference in heat of fusion Δ H_1－2Absolute value of (a).

Item 2. a packaging material for a battery, wherein,

which comprises a laminate comprising at least a substrate layer, a barrier layer and a heat-sealable resin layer in this order,

the substrate layer has a difference in heat of fusion Δ H determined by the following method_1－2A polybutylene terephthalate film having an absolute value of 3.0J/g or more.

The heat of fusion H measured at the 1 st time was measured by heating from-50 ℃ to 250 ℃ at a temperature rise rate of 10 ℃/min using a differential scanning calorimeter in accordance with the provisions of JIS K7122-2012₁. Then, the heat of fusion H is measured₁Then, the temperature was cooled from 250 ℃ to-50 ℃ at a cooling rate of 10 ℃/min, and then heated from-50 ℃ to 250 ℃ at a heating rate of 10 ℃/min, and the heat of fusion H measured at the 2 nd time was measured₂. The heat quantity of fusion H is calculated₁With heat of fusion H₂Difference in heat of fusion Δ H_1－2Absolute value of (a).

Item 3. the packaging material for a battery according to item 2, wherein,

the thickness of the polybutylene terephthalate film is 10 to 50 μm.

Item 4. the packaging material for a battery according to

item

2 or 3, wherein,

the barrier layer is made of an aluminum alloy foil.

The packaging material for a battery according to any one of claims 2 to 4, wherein,

an adhesive layer is provided between the barrier layer and the heat-fusible resin layer,

the adhesive layer contains a polyolefin resin.

The packaging material for a battery according to any one of claims 2 to 5, wherein,

the thickness of the adhesive layer is 10 μm or more.

The packaging material for a battery according to any one of claims 2 to 6, wherein,

the thickness of the polybutylene terephthalate film is 30 [ mu ] m or less.

Item 8 is a method for producing a packaging material for a battery, comprising a step of laminating at least a substrate layer comprising a polybutylene terephthalate film, a barrier layer and a heat-fusible resin layer in this order to obtain a laminate,

the difference in heat of fusion Δ H of the polybutylene terephthalate film was obtained by the following method_1－2The absolute value of (A) is 3.0J/g or more.

Based on the provisions of JIS K7122-2012, the heat of fusion H measured at the 1 st time was measured by heating from-50 ℃ to 250 ℃ at a temperature-rising rate of 10 ℃/min using a differential scanning calorimeter₁. Then, the heat of fusion H is measured₁Then, the temperature was increased from 250 ℃ to-50 ℃ at a temperature decrease rate of 10 ℃/min, then from-50 ℃ to 250 ℃ at a temperature increase rate of 10 ℃/min, and the heat of fusion H measured at the 2 nd time was measured₂. The heat quantity H of fusion is calculated₁With heat of fusion H₂Difference in heat of fusion Δ H_1－2The absolute value of (c).

The battery according to item 9, wherein a battery element having at least a positive electrode, a negative electrode, and an electrolyte is contained in a package formed of the battery packaging material according to any one of items 2 to 7.

Item 10. use of a polybutylene terephthalate film as a base material layer for a packaging material for a battery, which has a base material layer, a barrier layer and a heat-sealable resin layer in this order,

The heat of fusion H measured at the 1 st time was measured by heating from-50 ℃ to 250 ℃ at a temperature rise rate of 10 ℃/min using a differential scanning calorimeter in accordance with the provisions of JIS K7122-2012₁. Then, the heat of fusion H is measured₁Then, the sample was cooled from 250 ℃ to-50 ℃ at a cooling rate of 10 ℃/min, heated from-50 ℃ to 250 ℃ at a heating rate of 10 ℃/min, and the heat of fusion H measured at the 2 nd measurement was measured₂. The heat quantity of fusion H is calculated₁With heat of fusion H₂Difference in heat of fusion Δ H_1－2Absolute value of (a).

Effects of the invention

According to the present invention, a polybutylene terephthalate film can be provided which can impart excellent moldability to a battery packaging material by using a substrate layer for the battery packaging material having at least the substrate layer, a barrier layer, and a heat-sealable resin layer in this order. Further, the present invention can provide a battery packaging material using the polybutylene terephthalate film, a method for producing the battery packaging material, and a battery using the battery packaging material.

Drawings

FIG. 1 is a view showing an example of a cross-sectional structure of a polybutylene terephthalate film of the present invention.

Fig. 2 is a view showing an example of a cross-sectional structure of the battery packaging material of the present invention.

Fig. 3 is a view showing an example of a cross-sectional structure of the battery packaging material of the present invention.

Fig. 4 is a view showing an example of a cross-sectional structure of the battery packaging material of the present invention.

Fig. 5 is a view showing an example of a cross-sectional structure of the battery packaging material of the present invention.

FIG. 6 is a graph for explaining a difference in melting heat amount Δ H of a polybutylene terephthalate film_1－2Schematic diagram (graph) of the method for determining the absolute value of (1).

Detailed Description

The polybutylene terephthalate film of the present invention is a polybutylene terephthalate film used for a substrate layer of a battery packaging material having at least the substrate layer, a barrier layer, and a heat-sealable resin layer in this order, and is characterized in that: by the following methodDifference in heat of fusion Δ H obtained by the method_1－2The absolute value of (A) is 3.0J/g or more.

The polybutylene terephthalate film of the present invention has such characteristics that, when used as a base layer of a battery packaging material, the battery packaging material can exhibit excellent moldability. Hereinafter, the polybutylene terephthalate film of the present invention, a battery packaging material using the same, a method for producing the polybutylene terephthalate film, and a battery will be described in detail.

In the present specification, the numerical ranges indicated by "to" mean "above" and "below" with respect to the numerical ranges. For example, an expression of 2 to 15mm means 2mm to 15 mm.

1. Polybutylene terephthalate film

The polybutylene terephthalate film 11 of the present invention (hereinafter, the "polybutylene terephthalate" may be referred to as "PBT film") is a PBT film for a battery packaging material. More specifically, the polybutylene terephthalate film 11 of the present invention is used as the base material layer 1 of the battery packaging material 10 having the base material layer 1, the barrier layer 3, and the heat-sealable resin layer 4 in this order, as shown in fig. 2 to 5.

As described later, the base layer 1 of the battery packaging material 10 may be composed of only the PBT film 11 of the present invention as shown in fig. 2, 4, and 5, or may be provided with other layers such as a polyamide film 13 and an adhesive layer 12 for improving adhesion between the polyamide film 13 and the PBT film 11 in addition to the PBT film 11 of the present invention as shown in fig. 3. That is, the base material layer 1 may have a multilayer structure.

The substrate layer 1 of the battery packaging material 10 may be formed by laminating a plurality of layers of the PBT film 11 of the present invention, or may be formed by laminating the above-described difference in heat of fusion Δ H in addition to the PBT film 11 of the present invention_1－2Is lower than 3.0J/g of PBT film.

Specific examples of the case where the base layer 1 has a multilayer structure include a structure in which a PBT film 11, an adhesive layer 12, and a polyamide film 13 are laminated in this order; a structure in which a PBT film 11, an adhesive layer 12, and a PBT film 11 are laminated in this order; a structure in which a PBT film 11/a polyamide film 13 are laminated in this order; the PBT film 11/the PBT film 11 are sequentially laminated to form a structure; the PBT film 11/PET film is laminated in sequence to form a structure; a structure in which PET films/PBT films 11 are laminated in sequence; a structure in which a PBT film 11, an adhesive layer 12, and a PET film are laminated in this order; and a structure in which the PET film/adhesive layer 12/PBT film 11 are laminated in this order.

Since the PBT film is excellent in resistance (chemical resistance) when an electrolytic solution is attached, the PBT film is preferably positioned on the outermost layer side (the side opposite to the heat-fusible resin layer) in the battery packaging material 10.

Details of the laminate structure and the composition of each layer of the battery packaging material 10 will be described later.

The PBT film 11 of the invention has a difference in heat of fusion Δ H obtained by the method described later_1－2The absolute value of (A) is 3.0J/g or more, whereby the battery packaging material can exhibit excellent moldability. Namely, the difference Δ H in heat quantity due to melting_1－2Has an absolute value of 3.0J/g or more, and measures the heat of fusion H₁The crystal orientation in the former state is high, and it can be said that the crystal has a hardness range suitable for molding in the state of the battery packaging material. More specifically, in the process of forming the PBT film 11, the amount of heat of fusion of the PBT film 11 can be controlled by adjusting the type of film-forming method and the conditions during film-forming (for example, film-forming temperature, stretching ratio, cooling temperature, cooling rate, and heat-setting temperature after stretching)Difference Δ H_1－2The absolute value of (A) is set to 3.0J/g or more, whereby excellent moldability can be exhibited. Examples of the method for forming the PBT film 11 include a T-die method. Further, the difference Δ H in heat of fusion of the PBT film 11_1－2The absolute value of (b) can also be adjusted by the molecular weight, molecular weight distribution, etc. of the polybutylene terephthalate constituting the PBT film. In the PBT film 11, polybutylene terephthalate is a main component, and an additive may be appropriately contained as needed, or the additive may be used as the difference in heat of fusion Δ H_1－2Is set at the above range of factors.

From the viewpoint of further improving the moldability of the battery packaging material, the difference Δ H in heat of fusion as the PBT film 11_1－2The lower limit thereof includes: preferably about 3.0J/g or more, more preferably about 3.2J/g or more, more preferably about 3.4J/g or more, more preferably about 4.0J/g or more, more preferably 7.5J/g or more, more preferably 8.0J/g or more, and the upper limit thereof may be: preferably about 12J/g or less, more preferably about 11J/g or less, and still more preferably about 10J/g or less. In addition, the difference Δ H is the heat of fusion_1－2Preferable ranges of the absolute value of (b) include: about 3.0 to 12J/g, about 3.0 to 10J/g, about 3.2 to 12J/g, about 3.2 to 10J/g, about 3.4 to 12J/g, about 3.4 to 10J/g, about 4.0 to 12J/g, about 4.0 to 10J/g, about 7.5 to 12J/g, about 7.5 to 10J/g, about 8.0 to 12J/g, and about 8.0 to 10J/g. By making the difference of heat of fusion DeltaH of the PBT film 11_1－2The absolute value of (b) satisfies such a value, and the heat shrinkage ratio as a battery packaging material can be set to an appropriate value, and warpage occurring when the battery packaging material is molded with a mold or the like can be easily suppressed.

Further, the heat of fusion H of the PBT film 11₁Examples thereof include: for example, about-70 to-30J/g, preferably about-65 to-35J/g. Further, as the heat of fusion H₂Examples thereof include: for example, about-60 to-30J/g and about-55 to-35J/g. In the present invention, the PBT film 11 is preferably a molten heat H₁Less than heat of fusion H₂. That is, in the present invention, the heat of fusion H of the PBT film 11 is preferable₁Is greater thanHeat of fusion H₂Absolute value of (a).

In the present invention, the difference in heat of fusion Δ H of the PBT film_1－2The absolute value of (a) is obtained as follows.

A sample of a PBT film to be measured was set in a device, and then cooled from room temperature to-50 ℃ at a rate of 10 ℃ per minute in a nitrogen atmosphere, held at-50 ℃ for 15 minutes, and then heated to 250 ℃ at a rate of 10 ℃ per minute. The endothermic peak appearing at this time was defined as melting peak 1, and the heat of fusion thereof was defined as H₁. Then, after heating to 250 ℃, the mixture was held at 250 ℃ for 1 minute and cooled to-50 ℃ at a rate of 10 ℃/minute. After reaching-50 ℃ for 1 minute, the temperature was again raised to 250 ℃. The endothermic peak appearing at this time was taken as melting peak 2, and the heat of fusion H₁Similarly, the heat of fusion H₂. The difference (H) between the obtained 2 fusion heats was taken₁－H₂) As difference in heat of fusion Δ H_1－2To obtain a difference of fusion heat amount Δ H_1－2Absolute value of (a). More specifically, the thick line A in FIG. 6 is a schematic graph (a graph from-50 ℃ to 250 ℃) obtained when a sample is cooled from room temperature to-50 ℃ at a rate of 10 ℃/min, held at-50 ℃ for 15 minutes, and then heated to 250 ℃ at a rate of 10 ℃/min, and the thin line B in FIG. 6 is a schematic graph (a graph from-50 ℃ to 250 ℃) obtained when the sample is heated to 250 ℃ after the line A is taken, held at 250 ℃ for 1 minute, cooled to-50 ℃ at a rate of 10 ℃/min, held at-50 ℃ for 1 minute as it is, and reheated to 250 ℃. The graph of line B is an example showing a case having 2 endothermic peaks. The heat of fusion corresponds to the area of a region surrounded by a point where a line of a portion having an endothermic peak meets the base line in each graph. For example, heat of fusion H₁Is 2 points (among the 2 points, A1 is a point existing at a temperature of 180 ℃ to 200 ℃ and deviating from the base line before the transition of line A, A2 is a point existing at 230 ℃ to 240 ℃ and returning from the base line after the transition of line A) in the thick line A of FIG. 6 which is connected to the base line by a portion where an endothermic peak exists) The area of the enclosed region. In addition, for example, heat of fusion H₂The area of a region surrounded by 2 points (among the 2 points, B1 is a point existing at a temperature of 180 to 200 ℃ and deviating from the base line before the transition of line B, and B2 is a point existing at 230 to 240 ℃ and returning from the base line after the transition of line a) in which a portion having an endothermic peak is in contact with the base line in the thin line B of fig. 6. Wherein, generally, the melting peak of the PBT film is observed at about 210-230 ℃.

The polybutylene terephthalate film 11 of the present invention is a film made of polybutylene terephthalate. The ratio of polybutylene terephthalate contained in the polybutylene terephthalate film 11 includes: for example, 81% by mass or more, preferably 90% by mass or more, more preferably 99% by mass or more, and particularly preferably 100% by mass.

The thickness of the polybutylene terephthalate film 11 of the present invention is not particularly limited, but from the viewpoint of making the thickness of the battery packaging material thin and improving moldability, the lower limit thereof is: preferably about 10 μm or more, more preferably about 12 μm or more, and the upper limit thereof includes: preferably about 50 μm or less, more preferably about 45 μm or less, still more preferably 30 μm or less, and still more preferably 20 μm or less. Preferable ranges of the thickness of the polybutylene terephthalate film 11 include: about 10 to 50 μm, about 10 to 45 μm, about 10 to 30 μm, about 10 to 20 μm, about 12 to 50 μm, about 12 to 45 μm, about 12 to 30 μm, and about 12 to 20 μm.

Here, in the present invention, whether or not the difference Δ H in heat of fusion is the aforementioned difference_1－2The absolute value, thickness, etc. of the polybutylene terephthalate film can be determined by measuring the polybutylene terephthalate film alone. When polybutylene terephthalate is used as a base material layer in a battery packaging material comprising a laminate comprising a base material layer, a barrier layer and a heat-sealable resin layer in this order, the polybutylene terephthalate is taken from the laminate (for example, a PBT film is peeled off from the laminate or a layer other than the PBT film is dissolved), and the difference in heat of fusion Δ H is measured_1－2Absolute value, thickness, etc. ofWhether a polybutylene terephthalate film of the invention.

2. Packaging material for battery

As described above, the PBT film 11 of the invention can be preferably applied to the substrate layer 1 of the battery packaging material.

The battery packaging material 10 may have a laminate structure including a laminate including at least a base material layer 1, a barrier layer 3, and a heat-fusible resin layer 4 in this order. Fig. 2 to 5 show a manner in which the base layer 1, the barrier layer 3, and the heat-fusible resin layer 4 are sequentially stacked as an example of the cross-sectional structure of the battery packaging material 10. As shown in fig. 4 and 5, an adhesive layer 2 may be provided between the base material layer 1 and the barrier layer 3 as needed for the purpose of improving adhesion between these layers. As shown in fig. 4 and 5, an adhesive layer 5 may be provided between the barrier layer 3 and the heat-fusible resin layer 4 as needed for the purpose of improving adhesion between these layers. A surface coating layer 6 and the like may be provided on the outer side of the base material layer 1 (on the side opposite to the heat-fusible resin layer 4) as needed.

In the battery packaging material 10, the base material layer 1 is the outermost layer side, and the heat-sealable resin layer 4 is the innermost layer side. When assembling the battery, the battery element is sealed by bringing the surfaces of the heat-fusible resin layers 4 located around the battery element into contact with each other and then heat-fusing the battery element.

The thickness of the laminate constituting the battery packaging material 10 is not particularly limited, and from the viewpoint of making the thickness of the battery packaging material thin to improve the energy density of the battery and to obtain a battery packaging material having excellent moldability, there are exemplified: for example, about 180 μm or less, preferably about 150 μm or less, more preferably about 60 to 180 μm, and still more preferably about 60 to 150 μm.

[ base Material layer 1]

The base material layer 1 may include at least the PBT film 11 of the present invention, and may include other layers. The base layer 1 may be constituted only by the PBT film 11 of the present invention as shown in fig. 2, 4, and 5, for example, or may be constituted by other layers such as a polyamide film 13 and an adhesive layer 12 for improving adhesion between the polyamide film 13 and the PBT film 11 in addition to the PBT film 11 of the present invention as shown in fig. 3, for example.

Further, a plurality of the PBT films 11 of the present invention may be laminated on the base layer 1 of the battery packaging material 10, and the above-described difference in heat of fusion Δ H may be laminated in addition to the PBT films 11 of the present invention_1－2Is lower than 3.0J/g of PBT film.

When the substrate layer 1 is a single layer, the substrate layer 1 is formed of a polybutylene terephthalate film. When the base material layer 1 is formed of a plurality of layers, at least 1 layer of the base material layer 1 is formed of a polybutylene terephthalate film, and other layers may be included. The polybutylene terephthalate film is composed of polybutylene terephthalate, a copolyester mainly containing butylene terephthalate as a repeating unit, or the like. Specific examples of the copolyester mainly comprising a butylene terephthalate as a repeating unit include a copolyester mainly comprising a butylene terephthalate as a repeating unit and polymerized with a butylene isophthalate (hereinafter, abbreviated to poly (terephthalic acid/isophthalic acid) butylene terephthalate), poly (terephthalic acid/adipic acid) butylene terephthalate, poly (terephthalate/sebacic acid) butylene terephthalate, and poly (terephthalate/decanedicarboxylic acid) butylene terephthalate. The polybutylene terephthalate film may contain polyethylene terephthalate, a polyester elastomer, or the like.

The other layers may be formed of the polybutylene terephthalate film described above, or may be formed of other materials. The other materials are not particularly limited as long as they are insulating materials, and examples thereof include: polyesters (excluding polybutylene terephthalate, among others), polyamides, epoxy resins, acrylic resins, fluorine resins, polyurethanes, silicone resins, phenol resins, polycarbonate resins, polyetherimides, polyimides, and mixtures, copolymers, and the like of these.

Specific examples of the polyester include polyethylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and a copolyester mainly composed of ethylene terephthalate as a repeating unit. Further, as the copolyester mainly containing ethylene terephthalate as a repeating unit, specifically, there can be mentioned: copolymer polyesters obtained by polymerizing ethylene terephthalate with ethylene isophthalate as a main repeating unit (hereinafter, abbreviated as poly (terephthalic acid/isophthalic acid) glycol), poly (terephthalic acid/isophthalic acid) glycol, poly (terephthalic acid/adipic acid) glycol, poly (terephthalic acid/sodium sulfoisophthalate) glycol, poly (terephthalic acid/sodium isophthalate) glycol, poly (terephthalic acid/phenyl-dicarboxylic acid) glycol, poly (terephthalic acid/decanedicarboxylic acid) glycol, and the like. Examples of the other copolyester mainly composed of butylene terephthalate include polybutylene naphthalate and the like. These polyesters may be used alone in 1 kind, or 2 or more kinds may be used in combination. The polyester has advantages of excellent electrolyte resistance and being less likely to cause whitening due to adhesion of the electrolyte, and can be suitably used as a material for forming the substrate layer 1.

In addition, specific examples of the polyamide include: aliphatic polyamides such as nylon 6, nylon 66, nylon 610, nylon 12, nylon 46, and copolymers of nylon 6 and nylon 66; aromatic-containing polyamides such as hexamethylenediamine-isophthalic acid-terephthalic acid copolyamides including terephthalic acid and/or isophthalic acid-derived structural units such as nylon 6I, nylon 6T, nylon 6IT, and nylon 6I6T (I represents isophthalic acid and T represents terephthalic acid), and polyamides containing aromatics such as polymetaxylylene adipamide (MXD 6); alicyclic polyamides such as polyaminomethylcyclohexyl adipamide (PACM 6); polyamide obtained by copolymerizing a lactam component and an isocyanate component such as 4, 4' -diphenylmethane-diisocyanate, and polyester amide copolymers and polyether ester amide copolymers which are copolymers of a copolymerized polyamide with polyester and polyalkylene ether glycol; copolymers thereof, and the like. These polyamides may be used alone in 1 kind, or 2 or more kinds may be used in combination. The stretched polyamide film has excellent stretchability, can prevent whitening due to cracking of the resin of the base layer 1 during molding, and is suitable for use as a material for forming the base layer 1.

Specific examples of the case where the base layer 1 is formed of a plurality of layers include a multilayer structure in which a polybutylene terephthalate film and a polybutylene terephthalate film are laminated, a multilayer structure in which a polybutylene terephthalate film and a nylon film are laminated, and a multilayer structure in which a polybutylene terephthalate film and a polyester film (excluding a polybutylene terephthalate film) are laminated. For example, when the base layer 1 is formed of 2 resin films, a configuration in which a polybutylene terephthalate film and a polybutylene terephthalate film are laminated, a configuration in which a polybutylene terephthalate film and a nylon film are laminated, or a configuration in which a polybutylene terephthalate film and a polyethylene terephthalate film are laminated are preferable. Further, since the polybutylene terephthalate film is less likely to be discolored when an electrolyte solution adheres to the surface thereof, for example, when the base layer 1 has a multilayer structure including a nylon film, the base layer 1 is preferably a laminate having the nylon film and the polybutylene terephthalate film in this order from the barrier layer 3 side.

When the substrate layer 1 has a multilayer structure, the resin films may be bonded to each other with an adhesive or may be directly laminated without an adhesive. When the bonding is not performed by an adhesive, for example, a method of bonding in a hot-melt state such as a coextrusion method, a sandwich lamination method, or a hot lamination method can be mentioned. In the case of bonding with an adhesive, the adhesive used may be a two-component curing adhesive or a one-component curing adhesive. The bonding mechanism of the adhesive is not particularly limited, and may be any of a chemical reaction type, a solvent volatilization type, a hot melt type, a hot press type, an electron beam curing type, an ultraviolet curing type, and the like. Specific examples of the adhesive include those similar to those exemplified for the adhesive layer 2 described later. The thickness of the adhesive may be the same as that of the adhesive layer 2.

Specific examples of the multilayer structure of the base layer 1 include a structure in which a PBT film 11, an adhesive layer 12, and a polyamide film 13 are laminated in this order; a structure in which a PBT film 11, an adhesive layer 12, and a PBT film 11 are laminated in this order; a PBT film 11/a polyamide film 13 laminated in this order; the PBT film 11/the PBT film 11 are laminated in sequence; a PBT film 11/PET film laminated in sequence; a PBT film 11, an adhesive layer 12, and a PET film laminated in this order; PET film/adhesive layer 12/PBT film were laminated in this order.

In the present invention, from the viewpoint of improving the moldability of the battery packaging material, it is preferable that a lubricant is adhered to the surface of the base material layer 1. The lubricant is not particularly limited, but preferably includes an amide-based lubricant. Specific examples of the amide-based lubricant include saturated fatty amides, unsaturated fatty amides, substituted amides, methylol amides, saturated fatty bisamides, and unsaturated fatty bisamides. Specific examples of the saturated fatty amide include lauramide, palmitamide, stearamide, behenamide, and hydroxystearamide. Specific examples of the unsaturated fatty amide include oleamide and erucamide. Specific examples of the substituted amide include N-oleyl palmitamide, N-stearyl stearamide, N-stearyl oleamide, N-oleyl stearamide, N-stearyl erucamide and the like. Specific examples of the methylolamide include methylolstearylamide and the like. Specific examples of the saturated fatty bisamide include methylene bisstearamide, ethylene biscapramide, ethylene bislauramide, ethylene bisstearamide, ethylene bishydroxystearamide, ethylene bisbehenamide, hexamethylene bisstearamide, hexamethylene bisbehenamide, hexamethylene hydroxystearamide, N '-distearyldiamide, N' -distearyldisebacamide, and the like. Specific examples of the unsaturated fatty bisamide include ethylene bisoleamide, ethylene biserucamide, hexamethylene bisoleamide, N '-dioleyl adipamide, N' -dioleyl sebacamide, and the like. Specific examples of the fatty acid ester amide include stearamide ethyl stearate. Specific examples of the aromatic bisamide include xylylene bisstearamide, xylylene bishydroxystearamide, and N, N' -distearyl isophthalamide. The number of the lubricants may be 1 or 2 or more.

When the lubricant is present on the surface of the base layer 1, the amount of the lubricant present is not particularly limited, and may be preferably about 3mg/m in an environment of 24 ℃ and 60% relative humidity²More preferably 4 to 15mg/m²About, more preferably 5 to 14mg/m²Left and right.

The base material layer 1 may contain a lubricant. The lubricant present on the surface of the base material layer 1 may be formed by bleeding out a lubricant contained in a resin constituting the base material layer 1, or may be formed by applying a lubricant to the surface of the base material layer 1.

The thickness (total thickness) of the substrate layer 1 is preferably about 10 μm or more, and more preferably about 10 to 50 μm, from the viewpoint of reducing the thickness and improving the moldability of a battery packaging material using a substrate layer containing a polybutylene terephthalate film.

In the battery packaging material, the determination as to whether or not the polybutylene terephthalate of the present invention is used as the base material layer 1 can be made by measuring the aforementioned difference in heat of fusion Δ H alone for the polybutylene terephthalate peeled off from the laminate_1－2Absolute value, thickness, etc.

[ adhesive layer 2]

The adhesive layer 2 is a layer provided between the base layer 1 and the barrier layer 3 as necessary for firmly bonding them.

The adhesive layer 2 is formed of an adhesive capable of bonding the base layer 1 and the barrier layer 3. The adhesive used to form the adhesive layer 2 may be a two-component curing adhesive or a one-component curing adhesive. The adhesive used for forming the adhesive layer 2 is also not particularly limited, and may be any type such as a chemical reaction type, a solvent volatilization type, a hot melt type, and a hot press type.

Specific examples of the adhesive component that can be used to form the adhesive layer 2 include polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolyester; a polyether adhesive; a polyurethane adhesive; an epoxy resin; a phenolic resin-based resin; polyamide resins such as nylon 6, nylon 66, nylon 12, and copolyamide; polyolefin resins such as polyolefin, carboxylic acid-modified polyolefin, and metal-modified polyolefin, and polyvinyl acetate resins; a cellulose-based binder; (meth) acrylic resins; a polyimide-based resin; a polycarbonate; amino resins such as urea resins and melamine resins; rubbers such as chloroprene rubber, nitrile rubber, and styrene-butadiene rubber; silicone resins, and the like. These adhesive components can be used alone in 1, or can be used in combination of 2 or more. Among these adhesive components, a polyurethane adhesive is preferably used.

The adhesive layer 2 may contain a colorant such as a pigment.

The thickness of the adhesive layer 2 is not particularly limited as long as it functions as an adhesive layer, and may be, for example, about 0.1 to 10 μm, preferably about 0.5 to 5 μm.

[ Barrier layer 3]

In the battery packaging material, the barrier layer 3 is a layer having a function of improving the strength of the battery packaging material and preventing water vapor, oxygen, light, and the like from entering the battery. The barrier layer 3 is preferably a metal layer, i.e., a layer formed of a metal. Specific examples of the metal constituting the barrier layer 3 include aluminum, stainless steel, and titanium steel, and aluminum is preferably used. The barrier layer 3 can be formed of, for example, a metal foil, a metal vapor-deposited film, an inorganic oxide vapor-deposited film, a carbon-containing inorganic oxide vapor-deposited film, a film provided with these vapor-deposited films, or the like, and is preferably formed of a metal foil, and more preferably an aluminum alloy foil. In the production of the battery packaging material, the barrier layer is more preferably formed of an aluminum alloy foil or a stainless steel foil from the viewpoint of preventing the occurrence of wrinkles or pinholes in the barrier layer 3.

As the aluminum alloy foil, for example, it is more preferable to use a soft aluminum alloy foil such as an aluminum alloy foil subjected to annealing treatment (JIS H4160: 1994A 8021H-O, JIS H4160: 1994A 8079H-O, JIS H4000: 2014A 8021P-O, JIS H4000: 2014A 8079P-O).

Examples of the stainless steel foil include an austenitic stainless steel foil and a ferritic stainless steel foil. The stainless steel foil is preferably made of austenitic stainless steel.

Specific examples of austenitic stainless steel constituting the stainless steel foil include SUS304, SUS301, and SUS316L, and among them, SUS304 is particularly preferable.

In addition, at least one surface, preferably both surfaces of the barrier layer 3 are preferably subjected to a chemical surface treatment for stabilization of adhesion, prevention of dissolution, corrosion, or the like. Here, the chemical surface treatment refers to a treatment for forming an acid-resistant coating film on the surface of the barrier layer. When the acid-resistant coating film is formed on the surface of the barrier layer 3 of the present invention, the barrier layer 3 includes the acid-resistant coating film. Examples of the chemical surface treatment include: chromate treatment using a chromium compound such as chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, chromium oxalate, chromium dihydrogen phosphate, chromic acid acetoacetate, chromium chloride, or chromium potassium sulfate; phosphoric acid treatment using a phosphoric acid compound such as sodium phosphate, potassium phosphate, ammonium phosphate, or polyphosphoric acid; chromate treatment using an aminated phenol polymer, and the like.

The thickness of the barrier layer 3 is not particularly limited as long as it can function as a barrier layer for water vapor or the like, and may be, for example, about 10 to 50 μm, preferably about 10 to 40 μm.

[ Heat-fusible resin layer 4]

The heat-fusible resin layer 4 corresponds to an innermost layer, and is a layer in which the heat-fusible resin layers are heat-fused to each other at the time of assembling the battery to seal the battery element.

The resin component used for the heat-sealable resin layer 4 is not particularly limited as long as it can be heat-sealed, and examples thereof include polyolefin, cyclic polyolefin, acid-modified polyolefin, and acid-modified cyclic polyolefinA hydrocarbon. That is, the resin constituting the heat-fusible resin layer 4 may or may not contain a polyolefin skeleton, and preferably contains a polyolefin skeleton. The resin constituting the heat-sealable resin layer 4 containing a polyolefin skeleton can be analyzed by, for example, infrared spectroscopy, gas chromatography mass spectrometry, or the like, and the analysis method is not particularly limited. For example, when the maleic anhydride-modified polyolefin is measured by infrared spectroscopy, the wavenumber is 1760cm^-1Neighborhood and wavenumber 1780cm^-1A peak derived from maleic anhydride was detected in the vicinity. Among them, when the acid modification degree is low, the peak may become small and thus cannot be detected. In this case, the analysis can be performed by nuclear magnetic resonance spectroscopy.

Specific examples of the polyolefin include: polyethylene such as low density polyethylene, medium density polyethylene, high density polyethylene, and linear low density polyethylene; polypropylene such as homopolypropylene, a block copolymer of polypropylene (for example, a block copolymer of propylene and ethylene), a random copolymer of polypropylene (for example, a random copolymer of propylene and ethylene), and the like; ethylene-butene-propylene terpolymers, and the like. Among these polyolefins, polyethylene and polypropylene are preferably cited.

The cyclic polyolefin is a copolymer of an olefin and a cyclic monomer, and examples of the olefin which becomes a constituent monomer of the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, butadiene, isoprene, and the like. Examples of the cyclic monomer that constitutes the monomer of the cyclic polyolefin include cyclic olefins such as norbornene, and specifically, cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, and norbornadiene. Among these polyolefins, cyclic olefins are preferred, and norbornene is more preferred.

The above acid-modified polyolefin means: a polymer obtained by modifying the above polyolefin by block polymerization or graft polymerization with an acid component such as a carboxylic acid. Examples of the acid component used for modification include carboxylic acids such as maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride, and anhydrides thereof.

The above-mentioned acid-modified cyclic polyolefin means: a polymer obtained by copolymerizing a part of monomers constituting the cyclic polyolefin with an α, β -unsaturated carboxylic acid or an anhydride thereof, or block polymerization or graft polymerization of the α, β -unsaturated carboxylic acid or the anhydride thereof and the cyclic polyolefin. The cyclic polyolefin modified with a carboxylic acid is the same as described above. The carboxylic acid used for the modification is the same as the acid component used for the modification of the polyolefin.

Among these resin components, polyolefins such as polypropylene, carboxylic acid-modified polyolefins; more preferably, polypropylene and acid-modified polypropylene are mentioned.

The heat-fusible resin layer 4 may be formed of 1 resin component alone, or may be formed of a blend polymer in which 2 or more resin components are combined. The heat-fusible resin layer 4 may be formed of only 1 layer, or may be formed of 2 or more layers of the same or different resin components.

The thickness of the heat-fusible resin layer 4 is not particularly limited as long as the function as a heat-fusible resin layer is exhibited, and is preferably about 60 μm or less, and more preferably about 10 to 40 μm.

[ adhesive layer 5]

The adhesive layer 5 is provided between the barrier layer 3 and the heat-fusible resin layer 4 as needed to firmly adhere them.

The adhesive layer 5 is formed of a resin capable of bonding the barrier layer 3 and the heat-fusible resin layer 4. As the resin used for forming the adhesive layer 5, the same resin as the adhesive exemplified in the adhesive layer 2, such as the adhesion mechanism and the type of the adhesive component, can be used. As the resin used for forming the adhesive layer 5, polyolefin resins such as polyolefin, cyclic polyolefin, carboxylic acid-modified polyolefin, and carboxylic acid-modified cyclic polyolefin exemplified in the aforementioned heat-fusible resin layer 4 can be used. The polyolefin is preferably a carboxylic acid-modified polyolefin, and particularly preferably a carboxylic acid-modified polypropylene, from the viewpoint of excellent adhesion between the barrier layer 3 and the heat-fusible resin layer 4. That is, the resin constituting the adhesive layer 5 may or may not contain a polyolefin skeleton, and preferably contains a polyolefin skeletonAnd (3) a framework. The resin constituting the adhesive layer 5 containing a polyolefin skeleton can be analyzed by, for example, infrared spectroscopy, gas chromatography mass spectrometry, or the like, and the analysis method is not particularly limited. For example, when the maleic anhydride-modified polyolefin is measured by infrared spectroscopy, the wavenumber is 1760cm^－1Neighborhood and wavenumber 1780cm^－1A peak derived from maleic anhydride was detected in the vicinity. Among them, when the acid modification degree is low, the peak may become small and thus cannot be detected. In this case, the analysis can be performed by nuclear magnetic resonance spectroscopy.

Further, the adhesive layer 5 may be a cured product of a resin composition containing an acid-modified polyolefin and a curing agent, from the viewpoint of reducing the thickness of the battery packaging material and producing a battery packaging material having excellent shape stability after molding. As the acid-modified polyolefin, the same carboxylic acid-modified polyolefin and carboxylic acid-modified cyclic polyolefin as those exemplified in the heat-sealable resin layer 4 can be preferably exemplified.

The curing agent is not particularly limited as long as it is a curing agent for curing the acid-modified polyolefin. Examples of the curing agent include epoxy curing agents, polyfunctional isocyanate curing agents, carbodiimide curing agents, and oxazoline curing agents.

The epoxy curing agent is not particularly limited as long as it is a compound having at least 1 epoxy group. Examples of the epoxy curing agent include epoxy resins such as bisphenol a diglycidyl ether, modified bisphenol a diglycidyl ether, novolac glycidyl ether, glycerol polyglycidyl ether, and polyglycerol polyglycidyl ether.

The polyfunctional isocyanate-based curing agent is not particularly limited as long as it is a compound having 2 or more isocyanate groups. Specific examples of the polyfunctional isocyanate-based curing agent include isophorone diisocyanate (IPDI), Hexamethylene Diisocyanate (HDI), Toluene Diisocyanate (TDI), diphenylmethane diisocyanate (MDI), products obtained by polymerization or urethanization thereof, mixtures thereof, and copolymers with other polymers.

The carbodiimide-based curing agent is not particularly limited as long as it is a compound having at least 1 carbodiimide group (-N ═ C ═ N —). The carbodiimide-based curing agent is preferably a polycarbodiimide compound having at least 2 carbodiimide groups.

The oxazoline-based curing agent is not particularly limited as long as it is a compound having an oxazoline skeleton. Specific examples of the oxazoline curing agent include EPOCROS series produced by Nippon catalyst Kabushiki Kaisha.

The curing agent may be composed of 2 or more compounds from the viewpoint of improving the adhesion between the barrier layer 3 and the heat-fusible resin layer 4 by the adhesive layer 5.

The content of the curing agent in the resin composition forming the adhesive layer 5 is preferably about 0.1 to 50% by mass, more preferably about 0.1 to 30% by mass, and still more preferably about 0.1 to 10% by mass.

The thickness of the adhesive layer 5 is not particularly limited as long as it can function as an adhesive layer, and examples thereof include an upper limit of 50 μm or less, 40 μm or less, 30 μm or less, 10 μm or less, and 5 μm or less, and a lower limit of 0.1 μm or more, 0.5 μm or more, 1 μm or more, and 2 μm or more. Further, although not limited thereto, when an adhesive exemplified in the adhesive layer 2 is used, for example, it is preferably about 1 to 10 μm, more preferably about 1 to 5 μm. Further, although not limited thereto, when the resin exemplified in the heat-fusible resin layer 4 is used, it is preferably about 2 to 50 μm, more preferably about 10 to 40 μm. In the case of a cured product of an acid-modified polyolefin and a curing agent, the following are mentioned: preferably about 30 μm or less, more preferably about 0.1 to 20 μm, and further preferably about 0.5 to 5 μm. When the adhesive layer 5 is a cured product of a resin composition containing an acid-modified polyolefin and a curing agent, the adhesive layer 5 can be formed by applying the resin composition and curing the resin composition by heating or the like.

[ surface coating layer 6]

In the battery packaging material of the present invention, the surface-covering layer 6 may be provided on the substrate layer 1 (on the side opposite to the barrier layer 3 of the substrate layer 1) as necessary for the purpose of improving design properties, electrolyte resistance, scratch resistance, moldability, and the like. The surface coating layer 6 is a layer located at the outermost layer when the battery is assembled.

The surface coating layer 6 can be formed of, for example, polyvinylidene chloride, polyester resin, polyurethane resin, acrylic resin, epoxy resin, or the like. Among these, the surface coating layer 6 is preferably formed using a two-liquid curable resin. Examples of the two-component curable resin for forming the surface-covering layer 6 include two-component curable polyurethane resins, two-component curable polyester resins, and two-component curable epoxy resins. In addition, an additive may be blended in the surface covering layer 6.

Examples of the additive include fine particles having a particle diameter of about 0.5nm to 5 μm. The material of the additive is not particularly limited, and examples thereof include metals, metal oxides, inorganic substances, and organic substances. The shape of the additive is also not particularly limited, and examples thereof include a spherical shape, a fibrous shape, a plate shape, an amorphous shape, and a balloon (balloon) shape. Specific examples of the additive include talc, silica, graphite, kaolin, montmorillonite, synthetic mica, hydrotalcite, silica gel, zeolite, aluminum hydroxide, magnesium hydroxide, zinc oxide, magnesium oxide, aluminum oxide, neodymium oxide, antimony oxide, titanium oxide, cerium oxide, calcium sulfate, barium sulfate, calcium carbonate, calcium silicate, lithium carbonate, calcium benzoate, calcium oxalate, magnesium stearate, aluminum oxide, carbon black, carbon nanotubes, high-melting nylon, crosslinked acrylic acid, crosslinked styrene, crosslinked polyethylene, benzoguanamine, gold, aluminum, copper, and nickel. These additives may be used alone in 1 kind, or may be used in combination of 2 or more kinds. Among these additives, silica, barium sulfate, and titanium oxide are preferable from the viewpoints of dispersion stability, cost, and the like. The additive may be subjected to various surface treatments such as an insulating treatment and a high-dispersibility treatment in advance.

The method for forming the surface-covering layer 6 is not particularly limited, and for example, a method of applying a two-liquid curable resin for forming the surface-covering layer 6 on one surface of the base material layer 1 may be mentioned. When the additive is blended, the additive may be added to the two-liquid curable resin and mixed, followed by coating.

The thickness of the surface-covering layer 6 is not particularly limited as long as the above-described function as the surface-covering layer 6 can be exhibited, and may be, for example, about 0.5 to 10 μm, preferably about 1 to 5 μm.

3. Method for producing battery packaging material

The method for producing the battery packaging material is not particularly limited as long as a laminate obtained by laminating layers having a predetermined composition can be obtained. That is, the battery packaging material can be produced by a process comprising at least a step of sequentially laminating a substrate layer, a barrier layer and a heat-sealable resin layer, wherein the substrate layer uses the above-mentioned difference Δ H in heat of fusion_1－2A polybutylene terephthalate film having an absolute value of 3.0J/g or more.

An example of the method for producing the battery packaging material of the present invention is as follows. First, a laminate (hereinafter, also referred to as "laminate a") in which a base material layer 1, an adhesive layer 2, and a barrier layer 3 are laminated in this order is formed. Specifically, the laminate a can be formed by a dry lamination method including: the adhesive used for forming the adhesive layer 2 is applied on the substrate layer 1 or the barrier layer 3 whose surface is chemically treated as necessary by a coating method such as a gravure coating method or a roll coating method, and dried, and then the barrier layer 3 or the substrate layer 1 is laminated and the adhesive layer 2 is cured.

Next, the heat-fusible resin layer 4 is laminated on the barrier layer 3 of the laminate a. When the heat-fusible resin layer 4 is directly laminated on the barrier layer 3, a resin component constituting the heat-fusible resin layer 4 may be applied on the barrier layer 3 of the laminate a by a method such as a gravure coating method or a roll coating method. In addition, when the adhesive layer 5 is provided between the barrier layer 3 and the heat-fusible resin layer 4, for example, there are: (1) a method of laminating the barrier layer 3 of the laminate a by co-extrusion of the adhesive layer 5 and the heat-fusible resin layer 4 (co-extrusion lamination method); (2) a method of forming a laminate in which an adhesive layer 5 and a heat-fusible resin layer 4 are laminated, and laminating the laminate on the barrier layer 3 of the laminate A by a heat lamination method; (3) a method in which an adhesive for forming the adhesive layer 5 is laminated on the barrier layer 3 of the laminate a by a method such as extrusion or solution coating, drying at high temperature, and sintering, and the heat-fusible resin layer 4 formed in a sheet form in advance is laminated on the adhesive layer 5 by a heat lamination method; (4) a method (interlayer lamination method) in which the laminate a and the heat-fusible resin layer 4 are bonded to each other by the adhesive layer 5 while the molten adhesive layer 5 is poured between the barrier layer 3 of the laminate a and the heat-fusible resin layer 4 formed in a sheet form in advance.

When the surface coating layer is provided, the surface coating layer is laminated on the surface of the base material layer 1 opposite to the barrier layer 3. The surface-covering layer can be formed by, for example, applying the resin for forming the surface-covering layer to the surface of the base material layer 1. The order of the step of laminating the barrier layer 3 on the surface of the base material layer 1 and the step of laminating the surface-coating layer on the surface of the base material layer 1 is not particularly limited. For example, after the surface-covering layer is formed on the surface of the base material layer 1, the barrier layer 3 may be formed on the surface of the base material layer 1 opposite to the surface-covering layer.

In this way, a laminate comprising the surface-covering layer/the base material layer 1 provided as needed, the adhesive layer 2 provided as needed, the barrier layer 3 whose surface has been chemically surface-treated as needed, the adhesive layer 5 provided as needed, and the heat-fusible resin layer 4 can be formed, and the laminate can be subjected to heat treatment such as heat roller contact treatment, hot air treatment, near infrared treatment, or far infrared treatment in order to enhance the adhesiveness between the adhesive layer 2 provided as needed and the adhesive layer 5. The conditions for such heat treatment include, for example, 150 to 250 ℃ for 1 to 5 minutes.

In the battery packaging material, each layer constituting the laminate may be subjected to surface activation treatment such as corona treatment, sand blast treatment, oxidation treatment, ozone treatment, or the like as necessary in order to improve or stabilize film formability, lamination processing, 2-pass processing (packaging, embossing) suitability of the final product, or the like. For example, by applying corona treatment to at least one surface of the base material layer, the suitability for film formation, lamination, 2-pass processing of the final product, and the like can be improved or stabilized. Further, for example, by performing corona treatment on the surface of the base material layer 1 opposite to the barrier layer 3, the printability of the ink to the surface of the base material layer 1 can be improved.

4. Use of packaging material for battery

The battery packaging material can be used as a package for sealing and housing battery elements such as a positive electrode, a negative electrode, and an electrolyte. That is, a battery can be produced by housing a battery element having at least a positive electrode, a negative electrode, and an electrolyte in a package formed of a battery packaging material.

Specifically, the battery packaging material of the present invention is a battery using a battery packaging material, in which a battery element having at least a positive electrode, a negative electrode, and an electrolyte is covered so that metal terminals connected to the positive electrode and the negative electrode protrude outward and that flange portions (regions where heat-fusible resin layers contact each other) can be formed at the edges of the battery element, and the heat-fusible resin layers at the flange portions are heat-sealed to each other. When a battery element is housed in a package formed of the battery packaging material of the present invention, the package is formed such that a sealed portion of the battery packaging material of the present invention is an inner side (a surface in contact with the battery element).

The battery packaging material can be used for both primary batteries and secondary batteries, and is preferably a secondary battery. The type of secondary battery to which the battery packaging material of the present invention can be applied is not particularly limited, and examples thereof include a lithium ion battery, a lithium ion polymer battery, a lead storage battery, a nickel-hydrogen storage battery, a nickel-cadmium storage battery, a nickel-iron storage battery, a nickel-zinc storage battery, a silver oxide-zinc storage battery, a metal air battery, a polyvalent cation battery, a capacitor (condenser), and a capacitor (capacitor). Among these secondary batteries, lithium ion batteries and lithium ion polymer batteries are preferable as the objects of application of the battery packaging material of the present invention.

Examples

The present invention will be described in detail below by way of examples and comparative examples. However, the present invention is not limited to the examples.

Production of packaging Material for Battery

Examples 1 to 3 and comparative example 1

A barrier layer is laminated on the base material layer by a dry lamination method. As the substrate layer, those having a < difference in heat of fusion Δ H by the following description were used_1－2Method for obtaining absolute value of (1) > method of measuring the amount of fusion heat H shown in Table 1₁Heat of fusion H₂And difference in heat of fusion Δ H_1－2Biaxially stretched polybutylene terephthalate film (PBT film, thickness 15 μm). Further, as the barrier layer, an aluminum alloy foil (JIS H4160: 1994A 8021H-O, thickness 35 μm) having both surfaces chemically treated was used. Specifically, a two-pack type polyurethane adhesive (a polyol compound and an aromatic isocyanate compound) was applied to one surface of an aluminum alloy foil, and an adhesive layer (thickness 3 μm) was formed on the barrier layer. Next, the adhesive layer on the barrier layer and the base layer were laminated, and then subjected to a curing treatment, thereby producing a laminate of base layer/adhesive layer/barrier layer. Further, the chemical surface treatment of the aluminum foil used as the barrier layer is performed in the following manner: treating liquid containing phenolic resin, chromium fluoride compound and phosphoric acid is added so that the coating amount of chromium reaches 10mg/m²(dry mass) the aluminum foil was coated on both surfaces thereof by roll coating and sintered.

Next, an adhesive layer (having a thickness of 20 μm and disposed on the barrier layer side) containing a maleic anhydride-modified polypropylene resin and a heat-fusible resin layer (having a thickness of 15 μm and an innermost layer) containing a random polypropylene resin were coextruded on the barrier layer of the laminate to obtain a laminate film in which a base layer, an adhesive layer, a barrier layer, an adhesive layer and a heat-fusible resin layer were sequentially laminated. Next, the laminated film was subjected to a curing step to obtain the battery packaging materials of examples 1 to 3 and comparative example 1, respectively.

Comparative example 2

As the substrate layer, a biaxially stretched polybutylene terephthalate film (PBT film, thickness 15 μm) having a heat of fusion H shown in Table 1 was used in place of the biaxially stretched polybutylene terephthalate film₁Heat of fusion H₂And difference in heat of fusion Δ H_1－2A battery packaging material of comparative example 2 was obtained in the same manner as in example 1, except that the absolute value of (b) was changed to (d) in the case of biaxially stretching a polyethylene terephthalate film (PET film, thickness: 15 μm).

Comparative example 3

As the substrate layer, a biaxially stretched polybutylene terephthalate film (PBT film, thickness 15 μm) having a heat of fusion H shown in Table 1 was used in place of the biaxially stretched polybutylene terephthalate film₁Heat of fusion H₂And difference in heat of fusion Δ H_1－2A battery packaging material of comparative example 3 was obtained in the same manner as in example 1, except that the absolute value of (d) was changed to (d) biaxially stretched nylon (thickness: 15 μm).

Among them, in examples 1 to 3 and comparative examples 1 to 3, the heat of fusion H of each film₁Heat of fusion H₂And difference in heat of fusion Δ H_1－2The absolute values of (a) and (b) are set by adjusting the type of the film-forming method and conditions during film formation (for example, film-forming temperature, stretching ratio, cooling temperature, cooling rate, and heat-setting temperature after stretching) during film formation of these films.

< difference in Heat of fusion Δ H_1－2Method for obtaining absolute value of (1)

Heating from-50 deg.C to 250 deg.C at a temperature rise rate of 10 deg.C/min by using differential scanning calorimeter, and measuring the heat of fusion H measured at the 1 st time₁In the determination of the heat of fusion H₁Then, the sample was cooled from 250 ℃ to-50 ℃ at a cooling rate of 10 ℃/min, heated from-50 ℃ to 250 ℃ at a heating rate of 10 ℃/min, and the heat of fusion H measured at the 2 nd measurement was measured₂The quantity of heat of fusion H is calculated₁With the above heat of fusion H₂Difference in heat of fusion Δ H_1－2Absolute value of (a). The specific method is as follows. As the differential scanning calorimeter, "DSC 204F1 manufactured by NETZSCH corporation was usedPhoenix "used Proteus manufactured by NETZSCH as analysis software. In addition, an aluminum dish was used as a sample dish. In addition, the measurement was performed by placing a film sample in the apparatus, cooling the film sample from room temperature to-50 ℃ at a rate of 10 ℃/min under a nitrogen atmosphere, holding the film sample at-50 ℃ for 15 minutes, and then heating the film sample to 250 ℃ at a rate of 10 ℃/min. The endothermic peak appearing at this time was defined as melting peak 1, and the heat of fusion was defined as H₁. Subsequently, the mixture was heated to 250 ℃ and then kept at 250 ℃ for 1 minute, and then cooled to-50 ℃ at a rate of 10 ℃/minute. After reaching-50 ℃ for 1 minute, the temperature was again raised to 250 ℃. The endothermic peak occurring at this time was defined as melting peak 2 and melting heat quantity H₁Similarly, the heat of fusion H₂. Taking the difference (H) between the two obtained fusion heat quantities₁－H₂) Is defined as a difference of heat of fusion Δ H_1－2The absolute value is calculated. More specifically, the amount of heat of fusion is determined as described with reference to the schematic diagram of fig. 6, in each graph obtained by measurement with a differential scanning calorimeter, in accordance with the area of the region surrounded by the points at which the lines of the portions having endothermic peaks meet the base line.

< evaluation of moldability >

The battery packaging material was cut into a rectangular shape of 90Mm (MD) X150 mm (TD) to prepare a sample. For this sample, 10 samples were each cold-rolled using a forming die having a bore diameter of 32Mm (MD) x 54mm (TD) (for the female die surface, JIS B0659-1: 2002 appendix 1 (ref.) the maximum height roughness (nominal value of Rz) specified in Table 2 of the surface roughness standard sheet for comparison is 3.2 μm) and a forming die corresponding thereto (for the male die surface, JIS B0659-1: 2002 appendix 1 (ref.) the maximum height roughness (nominal value of Rz) specified in Table 2 of the surface roughness standard sheet for comparison is 1.6 μm), with a pressing pressure of 0.25MPa varying the forming depth in 0.5mm units from the forming depth of 0.5 mm. Further, the clearance between the male die and the female die was set to 0.5 mm. For the samples after cold rolling, Amm represents the deepest molding depth at which no pinholes or cracks were formed in the aluminum foil among 10 samples, B represents the number of samples at which pinholes or the like were formed in the aluminum foil among the shallowest molding depths at which pinholes or the like were formed, and the value calculated by the following equation was used as the molding depth of the battery packaging material.

The battery packaging material was formed to a depth of Amm + (0.5 mm/10) × (10-B)

The molding depth of the battery packaging material was calculated by rounding off the 2 nd position after the decimal point.

In the MD (machine direction) and TD (transverse direction) of the battery packaging material, the rolling direction of the aluminum foil is MD, and the vertical direction in the same plane as MD is TD. The rolling direction of the aluminum foil was confirmed by the rolling marks of the aluminum foil, and MD and TD of the battery packaging material were confirmed from the rolling direction.

< evaluation of chemical resistance >

A test piece having a size of 40 mm. times.40 mm was cut out from the battery packaging material obtained above. Next, 1 drop of an electrolyte solution (1 mol/l lithium hexafluorophosphate solution in a solvent of ethylene carbonate: diethyl carbonate: dimethyl carbonate: 1:1 (volume ratio)) was dropped onto the surface of the base material layer, and after leaving at 24 ℃ for 4 hours under an environment of a relative humidity of 50%, the electrolyte solution was wiped with a cloth containing isopropyl alcohol, and the change in the surface was observed. In this case, the case where the surface is not changed is denoted as a, and the case where the surface is discolored is denoted as C. The results are shown in Table 1.

[ Table 1]

In the battery packaging materials of examples 1 to 3, the difference in heat of fusion Δ H between the polybutylene terephthalate films used as the base material layers_1－2Has an absolute value of 3.0J/g or more, and is excellent in moldability and chemical resistance.

Description of the symbols

1 base material layer

2 adhesive layer

3 Barrier layer

4 Heat-fusible resin layer

5 adhesive layer

6 surface coating

10 Battery packaging Material

11 polybutylene terephthalate film

12 adhesive layer

13 Polyamide membrane

Claims

1. A polybutylene terephthalate film characterized by:

which is used for the base material layer of the packaging material for the battery at least comprising a base material layer, a barrier layer and a heat-fusible resin layer in this order,

the barrier layer is composed of a metal foil,

the polybutylene terephthalate film has a difference in heat of fusion Δ H obtained by the following method_1－2Has an absolute value of 3.0J/g or more,

difference in heat of fusion Δ H_1－2The method of obtaining the absolute value of (a) is as follows:

the heat of fusion H measured at the 1 st time was measured by heating from-50 ℃ to 250 ℃ at a temperature rise rate of 10 ℃/min using a differential scanning calorimeter in accordance with the provisions of JIS K7122-2012₁；

Then, the heat of fusion H is measured₁Then, the temperature was cooled from 250 ℃ to-50 ℃ at a cooling rate of 10 ℃/min, and then heated from-50 ℃ to 250 ℃ at a heating rate of 10 ℃/min, and the heat of fusion H measured at the 2 nd time was measured₂；

Calculating the heat of fusion H₁With heat of fusion H₂Difference in heat of fusion Δ H_1－2Absolute value of (a).

2. A packaging material for a battery, characterized in that:

the barrier layer is composed of a metal foil,

the substrate layer has a polybutylene terephthalate filmThe difference in heat of fusion Δ H of the alcohol ester film was determined by the following method_1－2Has an absolute value of 3.0J/g or more,

3. The packaging material for a battery according to claim 2, wherein:

the thickness of the polybutylene terephthalate film is 10-50 μm.

4. The packaging material for a battery according to claim 2 or 3, wherein:

the barrier layer is composed of an aluminum alloy foil.

5. The packaging material for batteries according to claim 2 or 3, wherein:

the adhesive layer contains a polyolefin resin.

6. The packaging material for batteries according to claim 2 or 3, wherein:

the thickness of the adhesive layer is 10 μm or more.

7. The packaging material for batteries according to claim 2 or 3, wherein:

the thickness of the polybutylene terephthalate film is less than 30 mu m.

8. A method for manufacturing a battery packaging material, characterized in that:

which comprises a step of laminating at least a substrate layer comprising a polybutylene terephthalate film, a barrier layer and a heat-sealable resin layer in this order to obtain a laminate,

the barrier layer is composed of a metal foil,

9. A battery, characterized by:

a battery element having at least a positive electrode, a negative electrode and an electrolyte is housed in a package formed of the battery packaging material according to any one of claims 2 to 7.