JP2023153951A - Polyethylene terephthalate film for packaging material for battery, packaging material for battery, method for manufacturing the same, and battery - Google Patents

Abstract

To provide a polyethylene terephthalate film for packaging material for battery, which allows a packaging material for battery to exhibit superior moldability when laminated as a base material layer of the packaging material for battery together with a barrier layer and a heat-fusable resin layer.SOLUTION: A polyethylene terephthalate film for packaging material for battery is to be used for a base material layer of a packaging material for battery, which has the base material layer, a barrier layer and a heat-fusable resin layer in this order. As for a stress-strain curve measured in a tensile test under the conditions of an inter-chuck distance of 50 mm and a tensile speed of 300 mm/min, and showing the relation between a stress (MPa) applied to the polyethylene terephthalate film and a strain at the time, when measuring an inclination of a straight line connecting between a yield point and a breaking point, the ratio STD/MD of an inclination STD of TD direction of the polyethylene terephthalate film to an inclination SMD of MD direction of the polyethylene terephthalate film is 0.8 or larger.SELECTED DRAWING: None

Description

The present invention relates to a polyethylene terephthalate film for battery packaging material, a battery packaging material, a method for manufacturing the battery packaging material, and a battery.

BACKGROUND OF THE INVENTION Various types of batteries have been developed in the past, and packaging materials have become essential components for sealing battery elements such as electrodes and electrolytes in all batteries. Traditionally, metal packaging materials were often used for battery packaging, but in recent years, with the increasing performance of electric vehicles, hybrid electric vehicles, computers, cameras, mobile phones, etc., batteries are now required to have a variety of shapes. At the same time, there is a demand for thinner and lighter weight devices. However, metal packaging materials, which have been widely used in the past, have the disadvantage that it is difficult to keep up with the diversification of shapes, and there is also a limit to the reduction in weight.

Therefore, in recent years, film-like packaging materials in which a base layer, an adhesive layer, a barrier layer, and a heat-fusible resin layer are sequentially laminated have been developed as a packaging material that can be easily processed into various shapes and can be made thinner and lighter. A laminate has been proposed (for example, see Patent Document 1). When using such a film-like packaging material, by heat-sealing the periphery of the packaging material with the heat-fusible resin layers located in the innermost layer of the packaging material facing each other, , the battery element is sealed with the packaging material.

For example, a resin film such as a polyamide film or a polyester film is used as the base material layer of such battery packaging material.

Japanese Patent Application Publication No. 2014-197559

When a film-like battery packaging material is used for a large battery such as a vehicle battery, a polyethylene terephthalate film may be used as the base layer in order to increase resistance to dielectric breakdown.

However, although polyethylene terephthalate films conventionally used as packaging materials for batteries have excellent resistance to dielectric breakdown, they have a problem of poor moldability. In particular, although film-like battery packaging materials are extremely thin, they have extremely high formability because they are subjected to cold forming for the purpose of forming a space to accommodate battery elements. is required. For this reason, the polyethylene terephthalate film required for such packaging materials for batteries is also required to have high moldability.

Under these circumstances, the present invention provides a battery packaging material that exhibits excellent moldability when laminated together with a barrier layer and a heat-fusible resin layer as a base layer of the battery packaging material. The main objective is to provide a polyethylene terephthalate film for battery packaging material that can be used as a battery packaging material.

The present inventors conducted extensive studies to solve the above problems. As a result, stress-strain, which shows the relationship between the stress (MPa) applied to the polyethylene terephthalate film and the strain at that time, was measured by a tensile test under the conditions of a distance between chucks of 50 mm and a tensile speed of 300 mm/min. In the curve, when measuring the slope of a straight line connecting the yield point and the breaking point, the slope S in the _MD direction of the polyethylene terephthalate film to the slope S in _{the TD} direction of the polyethylene terephthalate film. It has been found that by using a polyethylene terephthalate film having _{a TD/MD} of 0.8 or more as the base layer of the battery packaging material, the battery packaging material exhibits excellent moldability. The present invention was completed through further studies based on this knowledge.

That is, the present invention provides the inventions of the following aspects.
Item 1. A polyethylene terephthalate film used for the base layer of a battery packaging material comprising a base layer, a barrier layer, and a heat-fusible resin layer in this order,
In the stress-strain curve showing the relationship between the stress (MPa) applied to the polyethylene terephthalate film and the strain at that time, measured by a tensile test under the conditions of an inter-chuck distance of 50 mm and a tensile speed of 300 mm/min, When measuring the slope of a straight line connecting the yield point and the breaking point, the ratio S _TD of the slope S _TD in the TD direction of the polyethylene terephthalate film to the slope S MD in the MD direction of the polyethylene terephthalate film S _TD/MD is 0.8 or more, a polyethylene terephthalate film for battery packaging material.
Item 2. Item 1. The polyethylene terephthalate film for battery packaging material according to item 1, which has a thickness of 5 μm or more.
Item 3. It is composed of a laminate including at least a base material layer, a barrier layer, and a heat-fusible resin layer in this order,
The base layer includes a polyethylene terephthalate film,
In the stress-strain curve showing the relationship between the stress (MPa) applied to the polyethylene terephthalate film and the strain at that time, measured by a tensile test under the conditions of an inter-chuck distance of 50 mm and a tensile speed of 300 mm/min, When measuring the slope of a straight line connecting the yield point and the breaking point, the ratio S _TD of the slope S _TD in the TD direction of the polyethylene terephthalate film to the slope S MD in the MD direction of the polyethylene terephthalate film S _TD/MD is 0.8 or more, a battery packaging material.
Item 4. A battery, wherein a battery element including at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed from the battery packaging material according to item 3.
Item 5. At least a step of laminating a base material layer, a barrier layer, and a heat-fusible resin layer in this order to obtain a laminate,
The base layer includes a polyethylene terephthalate film,
In the stress-strain curve showing the relationship between the stress (MPa) applied to the polyethylene terephthalate film and the strain at that time, measured by a tensile test under the conditions of an inter-chuck distance of 50 mm and a tensile speed of 300 mm/min, When measuring the slope of a straight line connecting the yield point and the breaking point, the ratio S _TD of the slope S _TD in the TD direction of the polyethylene terephthalate film to the slope S MD in the MD direction of the polyethylene terephthalate film S _TD/MD is 0.8 or more, a method for producing a battery packaging material.

According to the present invention, when laminated together with a barrier layer and a heat-fusible resin layer as a base material layer of a battery packaging material, the battery packaging material can exhibit excellent moldability. A polyethylene terephthalate film for packaging material can be provided.

1 is a schematic cross-sectional view of a polyethylene terephthalate film of the present invention. 1 is a schematic cross-sectional view of an example of a battery packaging material using the polyethylene terephthalate film of the present invention as a base layer. 1 is a schematic cross-sectional view of an example of a battery packaging material using the polyethylene terephthalate film of the present invention as a base layer. FIG. 2 is a schematic diagram for explaining the yield point and breaking point of a stress-strain curve obtained by a tensile test. FIG. 2 is a schematic diagram (graph) for explaining how to determine the absolute value of the difference in heat of fusion ΔH _1-2 of a polyethylene terephthalate film.

The polyethylene terephthalate film of the present invention is used for the base layer of a battery packaging material comprising a base layer, a barrier layer, and a heat-fusible resin layer in this order. Further, the polyethylene terephthalate film of the present invention is characterized in that the slope ratio S _TD/MD determined by the following measurement is 0.8 or more.

(Measurement of the slope of the straight line connecting the yield point and fracture point by tensile test)
Each PET film sample is cut out to a size of 100 mm x 15 mm so that the long side direction is in the MD direction and the short side direction is in the TD direction. Using a tensile testing machine, the sample was pulled at a distance between chucks of 50 mm and a tensile speed of 300 mm/min to obtain a stress-strain curve. The tensile tests in the MD direction and the TD direction were conducted on 30 similarly prepared samples, and the yield point and fracture point were determined from the top five stress-strain curves in descending order of strain (elongation). Measure the slopes S _MD and S _TD of the connecting straight lines, calculate the slope ratio S TD/MD from the average value of the five slopes S _MD and the average value of the five slopes S _TD , and calculate the slope ratio S _{TD /} Find the value of _MD . This is because it can be said that the larger the strain in the sample, the more appropriate the state of the cross section at the time of sample preparation, and the less formed are creases that would affect the measurement results. The slopes S _MD and S _TD of the straight line connecting the yield point and the breaking point can be expressed by the following formulas, respectively.
Slope of the straight line connecting the yield point and the fracture point S _MD = {(Tensile fracture stress in the direction of MD) - (Tensile yield stress in the direction of MD)}/{(Tensile fracture strain in the direction of MD) - (Tensile fracture stress in the direction of MD) tensile yield strain in the direction)}
Slope of the straight line connecting the yield point and the fracture point S _TD = {(Tensile fracture stress in the direction of TD) - (Tensile yield stress in the direction of TD)}/{(Tensile fracture strain in the direction of TD) - (Tensile fracture stress in the direction of TD) tensile yield strain in the direction)}

Since the polyethylene terephthalate film of the present invention has such a specific slope ratio S _TD/MD , when it is laminated together with a barrier layer and a heat-fusible resin layer as a base layer of a battery packaging material, In addition, the battery packaging material can exhibit excellent moldability. Hereinafter, the polyethylene terephthalate film of the present invention and the battery of the present invention using the same will be described in detail.

In this specification, the numerical range indicated by "~" means "more than" or "less than". For example, the expression 2 to 15 mm means 2 mm or more and 15 mm or less.

1. Polyethylene terephthalate film The polyethylene terephthalate film 11 (hereinafter, "polyethylene terephthalate film" may be referred to as "PET film") of the present invention is a PET film for packaging material for batteries. More specifically, the polyethylene terephthalate film 11 of the present invention is a battery packaging comprising a base layer 1, a barrier layer 3, and a heat-fusible resin layer 4 in this order, as shown in FIGS. 2 and 3. It is used for the base material layer 1 of the material 10.

As will be described later, the base material layer 1 of the battery packaging material 10 only needs to contain at least the PET film 11 of the present invention, and for example, as shown in FIG. For example, as shown in FIG. 3, in addition to the PET film 11 of the present invention, a polyamide film 13 or an adhesive layer 12 for improving the adhesion between the polyamide film 13 and the PET film 11 may be added. Other layers may also be included. That is, the base material layer 1 may have a multilayer structure.

Further, the base material layer 1 of the battery packaging material 10 may have a plurality of PET films 11 of the present invention laminated thereon, and in addition to the PET film 11 of the present invention, the above-mentioned slope ratio S _TD/MD may be laminated. A PET film having a particle diameter of less than 0.8 may be further laminated.

Specific examples of the base material layer 1 having a multilayer structure include a structure in which PET film 11/adhesive layer 12/polyamide film 13 are laminated in this order; PET film 11/adhesive layer 12/PET film 11 in this order; A configuration in which PET film 11/polyamide film 13 are laminated in this order; a configuration in which PET film 11/PET film 11 are laminated in this order.

Since PET film has excellent resistance when electrolyte adheres to it, in battery packaging material 10, PET film is located on the outermost layer side (opposite side to the heat-fusible resin layer). is preferred.

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

The PET film 11 of the present invention has a yield point (upper yield point) in a stress-strain curve showing the relationship between stress (MPa) applied to a polyethylene terephthalate film and strain at that time, as measured by a tensile test. When measuring the inclination of the straight line connecting the point and the breaking point, the ratio of the inclination S _TD in the TD (Transverse Direction) direction of the polyethylene terephthalate film to the inclination S _MD in the MD (Machine Direction) direction of the polyethylene terephthalate film S _{TD /MD} is 0.8 or more. When the slope ratio S _TD/MD of the PET film 11 is 0.8 or more, the moldability of the battery packaging material can be improved. A schematic diagram for explaining the yield point and breaking point of the stress-strain curve obtained by the tensile test is shown in FIG. In the present invention, the yield point refers to the upper yield point. Normally, biaxially stretched PET films have different stretching ratios in the MD and TD directions due to their manufacturing method, and S _TD/MD is often far different from 1. Since the PET film 11 of the present invention has an appropriate S _TD/MD value close to 1, it can elongate more uniformly during molding of a battery packaging material and exhibit excellent moldability. The slope ratio S _TD/MD of the PET film 11 also depends on the type of film forming method and film forming conditions (for example, film forming temperature, stretching ratio, cooling temperature, cooling rate) during the film forming process of the PET film 11. , heat setting temperature after stretching) can be set to 0.8 or more. Note that the slope ratio STD _/MD of the PET film 11 is not determined only by the stretching ratio, but is also greatly influenced by the orientation of the resin depending on the conditions during extrusion of the resin (film forming temperature, cooling temperature, cooling rate, etc.). Even if the stretching ratio is the same in the MD direction and the TD direction, S _{TD /MD} is not necessarily close to 1 as in the PET film 11 of the present invention.

From the viewpoint of further improving the moldability of the battery packaging material, the lower limit of the slope ratio S _TD/MD of the PET film 11 is preferably about 0.9 or more, more preferably about 1.0 or more. The upper limit is preferably about 10.0 or less, more preferably about 7.0 or less, still more preferably about 5.0 or less. Further, the preferable range of the slope ratio S _TD/MD is about 0.8 to 10.0, about 0.8 to 7.0, about 0.8 to 5.0, and about 0.9 to 10.0. , approximately 0.9 to 7.0, approximately 0.9 to 5.0, approximately 1.0 to 10.0, approximately 1.0 to 7.0, approximately 1.0 to 5.0, 1.0 to approximately Examples include about 1.5 and about 1.1 to 1.3.

In the present invention, the slope ratio S _TD/MD of the PET film can be calculated by measuring the slope of a straight line connecting the yield point and the breaking point in a tensile test, as described above.

The slope S _MD of the PET film 11 is, for example, about 1.0 to 2.0, preferably about 1.2 to 1.9, more preferably about 1.8 to 1.9. _{The TD} is, for example, about 1.5 to 3.0, preferably about 1.6 to 2.2, and more preferably about 2.0 to 2.2.

In the above tensile test, the tensile yield stress at the yield point is preferably about 95 to 125 MPa in the MD direction, more preferably about 100 to 125 MPa, even more preferably about 104 to 120 MPa, and the tensile yield stress in the TD direction The pressure is preferably about 95 to 118 MPa, more preferably about 98 to 115 MPa. Further, the absolute value of the difference between the MD direction and the TD direction of the tensile yield stress is preferably about 0 to 20 MPa, particularly preferably about 0 to 16 MPa.

In the above tensile test, the tensile yield strain at the yield point is preferably about 100 to 115% in the MD direction, more preferably about 104 to 110%, and preferably 100 to 115% in the TD direction. degree, more preferably about 104 to 110%. Further, the absolute value of the difference between the MD direction and the TD direction of the tensile yield strain is preferably about 0 to 2%, particularly preferably about 0 to 0.1%.

Further, in the above tensile test, the tensile fracture stress at the breaking point is preferably about 150 to 250 MPa in the MD direction, more preferably about 158 to 245 MPa, and preferably about 185 to 280 MPa in the TD direction. , more preferably about 185 to 272 MPa, still more preferably about 192 to 272 MPa. Further, the absolute value of the difference between the MD direction and the TD direction of the tensile fracture stress is preferably about 0 to 105 MPa, more preferably about 0 to 20 MPa, and more preferably about 0 to 5 MPa. is particularly preferred.

In the above tensile test, the tensile fracture strain at the breaking point is preferably about 150 to 190% in the MD direction, more preferably about 160 to 188%, and preferably 160 to 190% in the TD direction. degree, more preferably about 163 to 182%. Further, the absolute value of the difference between the MD direction and the TD direction of the tensile fracture strain is preferably about 0 to 25%, particularly preferably about 0 to 10%.

The PET film 11 of the present invention is heated for the first time from 0°C to 300°C at a heating rate of 10°C/min using a differential scanning calorimeter in accordance with the provisions of JIS K7122-2012. After measuring the measured heat of fusion H ₁ and the heat of fusion H ₁ , the temperature was cooled from 300°C to 0°C at a cooling rate of 10°C/min. The heat of fusion difference ΔH _1-2 , which is the difference between the heat of fusion H ₂ measured a second time after heating from ℃ to 300 ℃, is preferably 6 J/g or more. When the difference in heat of fusion ΔH _1-2 of the PET film 11 is 6 J/g or more, the battery packaging material can exhibit even more excellent moldability. That is, since the heat of fusion difference ΔH _1-2 is 6 J/g or more, the crystal orientation before measuring the heat of fusion H ₁ is high, and it is suitable for molding into a battery packaging material. It can be said that it has a wide range of hardness. More specifically, in the process of forming the PET film 11, the type of film forming method and conditions during film forming (for example, film forming temperature, cooling temperature, cooling rate, heat setting temperature after stretching) are adjusted. Accordingly, the difference in heat of fusion ΔH _1-2 of the PET film 11 can be set to 6 J/g or more, and thereby excellent moldability can be exhibited. Examples of the method for forming the PET film 11 include a T-die method. Further, the difference in heat of fusion ΔH _1-2 of the PET film 11 can also be adjusted by the molecular weight and molecular weight distribution of polyethylene terephthalate constituting the PET film. In addition, although polyethylene terephthalate is the main component of the PET film 11, it may contain appropriate additives as necessary, and the additives are also factors for setting the difference in heat of fusion ΔH _1-2 within the above range. You can also use it as Among these factors, the heat setting temperature after stretching makes a large contribution to setting the difference in heat of fusion ΔH _1-2 within the above range.

From the viewpoint of further improving the moldability of the battery packaging material, the lower limit of the difference in heat of fusion ΔH _1-2 of the PET film 11 is more preferably about 7 J/g or more, and even more preferably about 8 J/g or more. , more preferably about 10 J/g or more, and the upper limit is preferably about 20 J/g or less, more preferably about 18 J/g or less, still more preferably about 16 J/g or less. Further, preferable ranges of the heat of fusion difference ΔH _1-2 are approximately 6 to 20 J/g, approximately 6 to 18 J/g, approximately 6 to 16 J/g, approximately 7 to 20 J/g, approximately 7 to 18 J/g, 7 to 16 J/g, 8 to 20 J/g, 8 to 18 J/g, 8 to 16 J/g, 10 to 20 J/g, 10 to 18 J/g, 10 to 16 J/g, 13 ~14 J/g can be mentioned.

Further, the heat of fusion H ₁ of the PET film 11 is, for example, about 45 to 60 J/g, preferably about 47 to 56 J/g, particularly preferably about 53 to 54 J/g, and the heat of fusion H ₂ is, For example, about 39 to 43 J/g, about 40 to 42 J/g, particularly preferably about 40 to 41 J/g.

In the present invention, the method for measuring the difference in heat of fusion ΔH _1-2 of PET film is as follows.

(Measurement of heat of fusion difference ΔH _1-2 )
After setting the PET film sample to be measured in the device, it was cooled from room temperature to 0°C at a rate of 10°C/min under a nitrogen atmosphere, held at 0°C for 15 minutes, and then cooled at a rate of 10°C/min. Heat to 300℃. The endothermic peak that appears at this time is defined as melting peak 1, and the heat of fusion is defined as _H1 . Next, the temperature was maintained at 300°C for 1 minute, and the temperature was cooled again to 0°C at a rate of 10°C/min. When the temperature reaches 0°C, it is held for 1 minute, and then heated again to 300°C at a rate of 10°C/min. The endothermic peak that appears at this time is defined as melting peak 2, and similarly to the heat of fusion _H1 , it is defined as the heat of fusion _H2 . The difference (H ₁ - H ₂ ) between the two heats of fusion thus obtained is taken as the difference in heats of fusion ΔH _1-2 , and the absolute value of the difference in heats of fusion ΔH _1-2 is obtained. To explain more specifically using the schematic diagram of FIG. 5, the thick line A in FIG. This is a schematic graph (graph from 0°C to 300°C) obtained when heating to 300°C at a rate of 10°C/min. After heating to 300°C, hold at 300°C for 1 minute, cool again to 0°C at a rate of 10°C/minute, once it reaches 0°C, hold for 1 minute, and then heat to 300°C again. This is a typical graph (graph from 0°C to 300°C). The graph of line B shows an example in which there are two endothermic peaks. In each graph, the heat of fusion corresponds to the area of the region surrounded by the point where the line where the endothermic peak exists and the base line are in contact. For example, the heat of fusion _H1 is determined by the thick line A in FIG. A2 is the point at which line A departs from the baseline before the transition, which exists between 260°C and 280°C, and where line A returns to the baseline after the transition) is the area of the region surrounded by. For example, the heat of fusion H ₂ is determined by the thin line B in Figure 5 at two points where the endothermic peak is in contact with the baseline (out of the two points, B1 is B2 is the point at which line B departs from the baseline before the transition, existing between 200°C, and B2 is the point at which line B returns to the baseline after the transition, existing between 260°C and 280°C. ) is the area of the region surrounded by Note that the melting peak of PET film is generally observed around 210 to 230°C.

The polyethylene terephthalate film 11 of the present invention is a film made of polyethylene terephthalate.

The thickness of the polyethylene terephthalate film 11 of the present invention is not particularly limited, but from the viewpoint of reducing the thickness of the battery packaging material and improving moldability, the lower limit is preferably about 5 μm or more, more preferably The upper limit is preferably about 40 μm or less, more preferably about 35 μm or less, and even more preferably about 30 μm or less. Preferred ranges of the thickness of the polyethylene terephthalate film 11 include approximately 5 to 40 μm, approximately 5 to 35 μm, approximately 5 to 30 μm, approximately 7 to 40 μm, approximately 7 to 35 μm, and approximately 7 to 30 μm.

In the present invention, whether or not the polyethylene terephthalate film has the above-mentioned slope ratio S _TD/MD , heat of fusion difference ΔH _1-2 , thickness, etc. is determined by measuring each polyethylene terephthalate film alone. be able to. Furthermore, when polyethylene terephthalate is used as the base layer of a battery packaging material comprising a laminate including a base layer, a barrier layer, and a heat-fusible resin layer in this order, The polyethylene terephthalate is obtained from the laminate (for example, by peeling the PET film from the laminate or dissolving layers other than the PET film. At this time, be careful not to stretch the PET film), The above-mentioned slope ratio S _TD/MD , difference in heat of fusion ΔH _1-2 , thickness, etc. are measured to determine whether it is the polyethylene terephthalate film of the present invention.

As described below, the MD direction and TD direction of the polyethylene terephthalate film laminated in the laminate can generally be determined from the barrier layer described below. That is, in a battery packaging material, MD and TD can generally be determined in the manufacturing process of a barrier layer, which will be described later. For example, when the barrier layer is made of aluminum foil, linear streaks called so-called rolling marks are formed on the surface of the aluminum foil in the rolling direction (RD) of the aluminum foil. Since the rolling marks extend along the rolling direction, the rolling direction of the aluminum foil can be determined by observing the surface of the aluminum foil. In addition, in the process of manufacturing a laminate, generally the MD of the laminate and the RD of the aluminum foil match, so the surface of the aluminum foil of the laminate is observed and the rolling direction (RD) of the aluminum foil is identified. By doing so, the MD of the laminate (that is, the MD of the polyethylene terephthalate film) can be specified. Furthermore, since the TD of the laminate is perpendicular to the MD of the laminate, the TD of the laminate (that is, the TD of the polyethylene terephthalate film) can also be specified.

In addition, in the present invention, the above-mentioned slope ratio S _TD/MD and heat of fusion difference ΔH _1-2 are different elements because their adjustment methods are different and the mechanisms for improving moldability are also different.

2. Battery Packaging Material As mentioned above, the PET film 11 of the present invention can be suitably used for the base layer 1 of a battery packaging material.

Examples of the battery packaging material 10 include those having a laminate structure consisting of a laminate including at least a base layer 1, a barrier layer 3, and a heat-fusible resin layer 4 in this order. 2 and 3, as an example of the cross-sectional structure of the battery packaging material 10, a base material layer 1, an adhesive layer 2, a barrier layer 3, an adhesive layer 5, and a heat-fusible resin layer 4 are laminated in this order. We will show you how. The adhesive layer 2 is a layer provided as necessary for the purpose of increasing the adhesion between the base material layer 1 and the barrier layer 3. Further, the adhesive layer 5 is a layer provided as necessary for the purpose of increasing the adhesion between the barrier layer 3 and the heat-fusible resin layer 4. A surface coating layer (not shown) or the like may be provided on the outside of the base layer 1 (on the side opposite to the heat-fusible resin layer 4), if necessary.

In the battery packaging material 10, the base layer 1 is the outermost layer, and the heat-fusible resin layer 4 is the innermost layer. When assembling the battery, the heat-fusible resin layers 4 located at the periphery of the battery element are brought into contact with each other and heat-sealed, thereby sealing the battery element.

The thickness of the laminate constituting the battery packaging material 10 is not particularly limited, but it is possible to reduce the thickness of the battery packaging material to increase the energy density of the battery and to provide a battery packaging material with excellent moldability. From the viewpoint of this, for example, it is about 180 μm or less, preferably about 150 μm or less, more preferably about 60 to 180 μm, and even more preferably about 60 to 150 μm.

[Base material layer 1]
The base layer 1 only needs to contain at least the PET film 11 of the present invention, and may contain other layers as long as the effects of the present invention are achieved. The base material layer 1 may be composed of only the PET film 11 of the present invention, as shown in FIG. 2, for example, or may be composed of, in addition to the PET film 11 of the present invention, as shown in FIG. Other layers such as the polyamide film 13 and an adhesive layer 12 for increasing the adhesion between the polyamide film 13 and the PET film 11 may be provided.

Further, the base layer 1 of the battery packaging material 10 may have a plurality of PET films 11 of the present invention laminated thereon, and in addition to the PET film 11 of the present invention, the above-mentioned slope ratio S _TD/MD is A PET film having a particle diameter of less than 0.8 may be further laminated.

The material of the other layers that may be included in the base layer 1 is not particularly limited as long as it has insulation properties, such as polyester (provided that the above slope ratio S _TD/MD is 0.8 or higher), polyamides, epoxy resins, acrylic resins, fluororesins, polyurethanes, silicone resins, phenolic resins, polycarbonate resins, polyetherimides, polyimides, and mixtures and copolymers thereof. Can be mentioned.

Specifically, polyesters include polyethylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and ethylene terephthalate as main repeating units, and the above-mentioned slope ratio STD _/MD is less than 0.8. Examples include polymerized polyester. In addition, as a copolymer polyester containing ethylene terephthalate as the main repeating unit, specifically, a copolymer polyester polymerized with ethylene isophthalate using ethylene terephthalate as the main repeating unit (hereinafter referred to as polyethylene (terephthalate/isophthalate)) ), polyethylene (terephthalate/isophthalate), polyethylene (terephthalate/adipate), polyethylene (terephthalate/sodium sulfoisophthalate), polyethylene (terephthalate/sodium isophthalate), polyethylene (terephthalate/phenyl-dicarboxylate) , polyethylene (terephthalate/decanedicarboxylate), and the like. Other copolyesters containing butylene terephthalate as a main repeating unit include polybutylene naphthalate. These polyesters may be used alone or in combination of two or more. Polyester has the advantage that it has excellent electrolyte resistance and does not easily cause whitening due to adhesion of electrolyte, and is therefore suitably used as the material for forming the base layer 1 .

Specific examples of polyamides include aliphatic polyamides such as nylon 6, nylon 66, nylon 610, nylon 12, nylon 46, and copolymers of nylon 6 and nylon 66; terephthalic acid and/or isophthalic acid. Hexamethylenediamine-isophthalic acid-terephthalic acid copolyamides, polymethaxylylene azide, etc. containing structural units derived from Aromatic polyamides such as Pamid (MXD6); alicyclic polyamides such as polyaminomethylcyclohexyladipamide (PACM6); and copolymerization of lactam components and isocyanate components such as 4,4'-diphenylmethane-diisocyanate. Examples include polyesteramide copolymers and polyetheresteramide copolymers, which are copolymers of copolyamides, polyesters, and polyalkylene ether glycol; copolymers of these. These polyamides may be used alone or in combination of two or more. The stretched polyamide film has excellent stretchability and can prevent the occurrence of whitening due to resin cracking of the base layer 1 during molding, and is suitably used as a material for forming the base layer 1.

When the base material layer 1 has a multilayer structure, each resin film may be adhered via an adhesive (adhesive layer 12), or may be directly laminated without using an adhesive. In the case of adhering without using an adhesive, for example, a method of adhering in a hot melt state such as a coextrusion method, a sandwich lamination method, a thermal lamination method, etc. can be mentioned. Further, when bonding is performed via an adhesive, the adhesive used may be a two-component curing adhesive or a one-component curing adhesive. Furthermore, the bonding mechanism of the adhesive is not particularly limited, and may be any of the chemical reaction type, solvent volatilization type, heat melting type, heat pressure type, electron beam curing type, and ultraviolet curing type. Specific examples of the adhesive include adhesives similar to those exemplified in adhesive layer 2 described later. Further, the thickness of the adhesive can also 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 PET film 11/adhesive layer 12/polyamide film 13 are laminated in this order; a structure in which PET film 11/adhesive layer 12/PET film 11 are laminated in this order; Examples include a configuration in which PET film 11/polyamide film 13 are laminated in this order; and a configuration in which PET film 11/PET film 11 are laminated in this order.

Since PET film has excellent resistance when electrolyte adheres to it, in battery packaging material 10, PET film is located on the outermost layer side (opposite side to the heat-fusible resin layer). is preferred.

In the present invention, from the viewpoint of improving the moldability of the battery packaging material, it is preferable that a lubricant be attached to the surface of the base layer 1. The lubricant is not particularly limited, but preferably includes an amide lubricant. Specific examples of amide lubricants include saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylolamides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, and the like. Specific examples of saturated fatty acid amides include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, hydroxystearic acid amide, and the like. Specific examples of unsaturated fatty acid amides include oleic acid amide and erucic acid amide. Specific examples of substituted amides include N-oleyl palmitic acid amide, N-stearyl stearic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, N-stearyl erucic acid amide, and the like. Furthermore, specific examples of methylolamide include methylolstearamide and the like. Specific examples of saturated fatty acid bisamides include methylene bisstearamide, ethylene biscapric acid amide, ethylene bislauric acid amide, ethylene bisstearic acid amide, ethylene bishydroxystearic acid amide, ethylene bisbehenic acid amide, and hexamethylene bis stearic acid amide. Examples include acid amide, hexamethylene bisbehenic acid amide, hexamethylene hydroxystearic acid amide, N,N'-distearyl adipic acid amide, N,N'-distearyl sebacic acid amide, and the like. Specific examples of unsaturated fatty acid bisamides include ethylene bisoleic acid amide, ethylene biserucic acid amide, hexamethylene bisoleic acid amide, N,N'-dioleyladipic acid amide, and N,N'-dioleyl sebacic acid amide. Examples include. Specific examples of fatty acid ester amides include stearamide ethyl stearate. Specific examples of aromatic bisamides include m-xylylene bisstearamide, m-xylylene bishydroxystearamide, and N,N'-distearylisophthalic acid amide. One type of lubricant may be used alone, or two or more types may be used in combination.

The content of the lubricant in the base layer 1 is not particularly limited, and from the viewpoint of improving the moldability and insulation properties of the battery packaging material, it is preferably about 0.01 to 0.2% by mass, more preferably 0. An example is about .05 to 0.15% by mass.

The thickness of the base layer 1 is, for example, 5 μm or more, preferably about 5 to 50 μm, more preferably about 10 to 50 μm, and even more preferably about 15 to 30 μm.

In a battery packaging material, whether or not the polyethylene terephthalate of the present invention is used as the base layer 1 can be determined by the above-mentioned slope ratio S _TD/MD and heat of fusion difference ΔH for the polyethylene terephthalate alone peeled from the laminate. _1-2 , it can be determined by measuring the thickness etc.

Further, in the battery packaging material, the MD direction and TD direction of the polyethylene terephthalate film laminated in the laminate can be determined, for example, from the barrier layer described below, as described above.

[Adhesive layer 2]
The adhesive layer 2 is a layer provided between the base material layer 1 and the barrier layer 3 as necessary in order to firmly adhere them.

The adhesive layer 2 is formed of an adhesive capable of bonding the base material layer 1 and the barrier layer 3 together. The adhesive used to form the adhesive layer 2 may be a two-component curing adhesive or a one-component curing adhesive. Furthermore, the bonding mechanism of the adhesive used to form the adhesive layer 2 is not particularly limited, and may be any one of a chemical reaction type, a solvent volatilization type, a heat melt type, a heat pressure type, and the like.

Specifically, adhesive components 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 copolymerized polyester; polyether Polyurethane adhesives; Epoxy resins; Phenolic resins; Polyamide resins such as nylon 6, nylon 66, nylon 12, and copolyamide; Polyolefins such as polyolefins, carboxylic acid-modified polyolefins, and metal-modified polyolefins Resin, polyvinyl acetate resin; cellulose adhesive; (meth)acrylic resin; polyimide resin; polycarbonate; amino resin such as urea resin, melamine resin; rubber such as chloroprene rubber, nitrile rubber, styrene-butadiene rubber; Examples include silicone resin. These adhesive components may be used alone or in combination of two or more. Among these adhesive components, polyurethane adhesives are preferred.

The thickness of the adhesive layer 2 is not particularly limited as long as it functions as an adhesive layer, but 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 that not only improves the strength of the battery packaging material but also has the function of preventing water vapor, oxygen, light, etc. from entering the inside of the battery. The barrier layer 3 is preferably a metal layer, that is, a layer made of metal. Specific examples of the metal constituting the barrier layer 3 include aluminum, stainless steel, and titanium, with aluminum being preferred. 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, etc., and may be formed of a metal foil. is preferred, and more preferably made of aluminum foil or stainless steel foil.

When the barrier layer 3 is made of aluminum foil, the aluminum foil is made of an aluminum alloy. From the viewpoint of preventing wrinkles and pinholes from occurring in the barrier layer 3 during the production of battery packaging materials, the barrier layer is made of, for example, annealed aluminum (JIS H4160:1994 A8021H-O, JIS H4160: It is more preferable to use soft aluminum foil such as 1994 A8079H-O, JIS H4000:2014 A8021P-O, JIS H4000:2014 A8079P-O).

Furthermore, when the barrier layer 3 is made of stainless steel foil, the stainless steel foil is preferably made of austenitic stainless steel. This results in a battery packaging material that has high puncture strength, excellent electrolyte resistance, and moldability. Specific examples of austenitic stainless steel include SUS304, SUS301, SUS316L, etc. Among these, SUS304 is particularly preferred. In addition, the stainless steel foil has particularly improved spreadability and formability by being subjected to cold rolling treatment. Furthermore, by performing heat treatment and annealing after cold rolling, the balance between the flow direction and the width direction is improved and formability is improved. Furthermore, in order to stabilize the effect of the chemical conversion treatment described below, it is important to include a surface cleaning step after the rolling treatment or heat treatment. Examples of the cleaning method include cleaning using an alkali or acid, and alkaline electrolytic degreasing. Further, it is also possible to use ultrasonic treatment, plasma treatment, etc. in combination. Preferably, alkaline degreasing cleaning or alkaline electrolytic degreasing is preferred. These improve surface wettability, make chemical conversion treatment uniform, and stabilize content resistance.

It is preferable that at least one surface, preferably both surfaces, of the barrier layer 3 is subjected to a chemical conversion treatment in order to stabilize adhesion and prevent dissolution and corrosion. Here, chemical conversion treatment refers to treatment for forming an acid-resistant film on the surface of the barrier layer. Examples of chemical conversion treatments include chromate chromate treatment using chromium compounds such as chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, chromium oxalate, chromium diphosphate, chromate acetylacetate, chromium chloride, potassium chromium sulfate, etc. ; 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 functions as a water vapor barrier layer, but it can be, for example, about 10 to 50 μm, preferably about 10 to 45 μm.

[Thermofusible resin layer 4]
The heat-fusible resin layer 4 corresponds to the innermost layer, and is a layer that seals the battery element by thermally fusing the heat-fusible resin layers to each other during battery assembly.

The resin component used in the heat-fusible resin layer 4 is not particularly limited as long as it is heat-fusible, and examples thereof include polyolefin, cyclic polyolefin, acid-modified polyolefin, and acid-modified cyclic polyolefin. 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 fact that the resin constituting the heat-fusible resin layer 4 contains a polyolefin skeleton can be analyzed by, for example, infrared spectroscopy, gas chromatography mass spectrometry, etc., and the analysis method is not particularly limited. For example, when a maleic anhydride-modified polyolefin is measured by infrared spectroscopy, peaks derived from maleic anhydride are detected at wave numbers around 1760 cm ^-1 and around 1780 cm ^-1 wave numbers. However, if the degree of acid modification is low, the peak may become small and may not be detected. In that case, it can be analyzed by nuclear magnetic resonance spectroscopy.

Specifically, the polyolefins include polyethylenes such as low density polyethylene, medium density polyethylene, high density polyethylene, and linear low density polyethylene; homopolypropylene, block copolymers of polypropylene (for example, block copolymers of propylene and ethylene), and polypropylene. polypropylene, such as a random copolymer of (eg, a random copolymer of propylene and ethylene); terpolymers of ethylene-butene-propylene, and the like. Among these polyolefins, polyethylene and polypropylene are preferred.

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

The acid-modified polyolefin is a polymer obtained by modifying the 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, or their anhydrides.

The acid-modified cyclic polyolefin is produced by copolymerizing a part of the monomers constituting the cyclic polyolefin in place of α,β-unsaturated carboxylic acid or its anhydride, or by copolymerizing a part of the monomers constituting the cyclic polyolefin with α,β-unsaturated carboxylic acid or its anhydride, or It is a polymer obtained by block polymerization or graft polymerization of unsaturated carboxylic acids or their anhydrides. The cyclic polyolefin modified with carboxylic acid is the same as described above. Further, the carboxylic acid used for modification is the same as that used for modification of the polyolefin.

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

The heat-fusible resin layer 4 may be formed from one type of resin component alone, or may be formed from a blend polymer that is a combination of two or more types of resin components. Furthermore, the heat-fusible resin layer 4 may be formed of only one layer, but may be formed of two or more layers made of the same or different resin components.

Further, the heat-fusible resin layer 4 may contain a lubricant or the like, if necessary. When the heat-fusible resin layer 4 contains a lubricant, the moldability of the battery packaging material can be improved. The lubricant is not particularly limited, and any known lubricant can be used, such as those exemplified for the base layer 1 above. The lubricants may be used alone or in combination of two or more. The content of the lubricant in the heat-fusible resin layer 4 is not particularly limited, and from the viewpoint of improving the moldability and insulation properties of the battery packaging material, it is preferably about 0.01 to 0.20% by mass, more preferably about 0.01 to 0.20% by mass. Preferably, it is about 0.05 to 0.15% by mass.

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

[Adhesive layer 5]
The adhesive layer 5 is a layer provided between the barrier layer 3 and the heat-fusible resin layer 4 as necessary in order to firmly adhere them.

The adhesive layer 5 is formed of a resin that can bond the barrier layer 3 and the heat-fusible resin layer 4 together. As the resin used to form the adhesive layer 5, the same adhesive as the adhesive exemplified for the adhesive layer 2 can be used with respect to its adhesive mechanism, type of adhesive component, etc. Furthermore, as the resin used for forming the adhesive layer 5, polyolefin resins such as the polyolefin, cyclic polyolefin, carboxylic acid-modified polyolefin, and carboxylic acid-modified cyclic polyolefin exemplified in the above-mentioned heat-fusible resin layer 4 can also be used. . From the viewpoint of excellent adhesion between the barrier layer 3 and the heat-fusible resin layer 4, the polyolefin is preferably a carboxylic acid-modified polyolefin, and particularly preferably a carboxylic acid-modified polypropylene. That is, the resin constituting the adhesive layer 5 may or may not contain a polyolefin skeleton, and preferably contains a polyolefin skeleton. The fact that the resin constituting the adhesive layer 5 contains a polyolefin skeleton can be analyzed by, for example, infrared spectroscopy, gas chromatography mass spectrometry, etc., and the analytical method is not particularly limited. For example, when a maleic anhydride-modified polyolefin is measured by infrared spectroscopy, peaks derived from maleic anhydride are detected at wave numbers around 1760 cm ^-1 and around 1780 cm ^-1 wave numbers. However, if the degree of acid modification is low, the peak may become small and may not be detected. In that case, it can be analyzed by nuclear magnetic resonance spectroscopy.

Furthermore, from the viewpoint of reducing the thickness of the battery packaging material and providing a battery packaging material with excellent shape stability after molding, the adhesive layer 5 is made of a resin composition containing an acid-modified polyolefin and a curing agent. It may be a cured product. Preferably, the acid-modified polyolefin is the same as the carboxylic acid-modified polyolefin and carboxylic acid-modified cyclic polyolefin exemplified in the heat-fusible resin layer 4.

Further, the curing agent is not particularly limited as long as it cures 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 one 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, glycerin polyglycidyl ether, and polyglycerin polyglycidyl ether.

The polyfunctional isocyanate curing agent is not particularly limited as long as it is a compound having two or more isocyanate groups. Specific examples of polyfunctional isocyanate curing agents include isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymerized or nurated products of these, and Examples include mixtures and copolymers with other polymers.

The carbodiimide curing agent is not particularly limited as long as it is a compound having at least one carbodiimide group (-N=C=N-). As the carbodiimide curing agent, a polycarbodiimide compound having at least two carbodiimide groups is preferred.

The oxazoline 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 the Epocross series manufactured by Nippon Shokubai Co., Ltd.

From the viewpoint of increasing the adhesion between the barrier layer 3 and the heat-fusible resin layer 4 by the adhesive layer 5, the curing agent may be composed of two or more types of compounds.

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

The thickness of the adhesive layer 5 is not particularly limited as long as it functions as an adhesive layer, but if the adhesive exemplified for the adhesive layer 2 is used, the thickness is preferably about 1 to 10 μm, more preferably about 1 μm. ~5 μm, for example. Further, when using the resin exemplified for the heat-fusible resin layer 4, the thickness is preferably about 2 to 50 μm, more preferably about 10 to 40 μm. Further, in the case of a cured product of an acid-modified polyolefin and a curing agent, the thickness is preferably about 30 μm or less, more preferably about 0.1 to 20 μm, and even more preferably about 0.5 to 5 μm. In addition, 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 it by heating or the like.

[Surface coating layer]
In the battery packaging material of the present invention, for the purpose of improving design, electrolyte resistance, abrasion resistance, moldability, etc., if necessary, on the base layer 1 (barrier layer of base layer 1). If necessary, a surface coating layer may be provided on the side opposite to 3). The surface coating layer is the outermost layer when the battery is assembled.

The surface coating layer can be formed from a resin composition. As described below, the components contained in the resin composition include resin components, curing accelerators, and additives (fillers, etc.).

The resin component contained in the resin composition preferably includes a thermosetting resin. Any thermosetting resin may be used as long as it polymerizes when heated to form a polymer network structure and harden. Specific examples of thermosetting resins include polyvinylidene chloride, polyester resins, epoxy resins, amino resins (melamine resins, benzoguanamine resins, etc.), acrylic resins, urethane resins, phenolic resins, unsaturated polyester resins, alkyd resins, etc. can be mentioned.

Among these thermosetting resins, urethane resins and epoxy resins are preferred from the viewpoint of shortening curing time, improving moldability and chemical resistance, and more preferably two-component curable urethane resins and two-component curable urethane resins. Examples include liquid-curable epoxy resins, and particularly preferred are two-component curable epoxy resins.

Examples of two-component curable urethane resin include a combination of a polyol compound (base resin) and an isocyanate compound (curing agent), and examples of two-component curable epoxy resin include an epoxy resin (base resin). and an acid anhydride, an amine compound, or an amino resin (curing agent). Further, as the two-component curable urethane resin, a polyfunctional urethane (meth)acrylate consisting of a combination of a polyfunctional (meth)acrylate (base resin) having active hydrogen and a polyisocyanate (curing agent) is also preferred.

In the two-component curable urethane resin, the polyol compound used as the main ingredient is not particularly limited, but examples thereof include polyester polyol, polyester polyurethane polyol, polyether polyol, polyether polyurethane polyol, and the like. These polyol compounds may be used alone or in combination of two or more.

In the two-component curable urethane resin, the isocyanate compound used as a curing agent is not particularly limited, but includes, for example, polyisocyanate, its adduct, its isocyanurate modified product, its carbodiimide modified product, and its allophanate modified product. , its burette modified product, etc. Specific examples of polyisocyanates include diphenylmethane diisocyanate (MDI), polyphenylmethane diisocyanate (polymeric MDI), tolylene diisocyanate (TDI), hexamethylene diisocyanate (HDI), and bis(4-isocyanatecyclohexyl)methane (H12MDI). , isophorone diisocyanate (IPDI), 1,5-naphthalene diisocyanate (1,5-NDI), 3,3'-dimethyl-4,4'-diphenylene diisocyanate (TODI), xylene diisocyanate (XDI) and other aromatic diisocyanates. ; Aliphatic diisocyanates such as tramethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and isophorone diisocyanate; Alicyclic diisocyanates such as 4,4'-methylene bis(cyclohexyl isocyanate) and isophorone diisocyanate; 1,5-naphthalene diisocyanate (1 , 5-NDI) and the like. Specific examples of adducts include those obtained by adding trimethylolpropane, glycol, etc. to the above polyisocyanate. These isocyanate compounds may be used alone or in combination of two or more.

Moreover, these thermosetting resins may be crosslinkable elastomers. A crosslinkable elastomer is a thermosetting resin that can impart a soft segment to a cured product. For example, in the case of a two-component curable urethane resin or a two-component curable epoxy resin among crosslinkable elastomers, it is sufficient that the above-mentioned base resin has a structure capable of imparting a soft segment. The crosslinkable elastomer can be used as a part of the thermosetting resin used to form the layer constituting the surface coating layer in order to provide the layer constituting the surface coating layer with a desired hardness.

These thermosetting resins may be used alone or in combination of two or more. Further, the surface coating layer may be formed of a plurality of layers. When the surface coating layer is formed of multiple layers, the thermosetting resin used in each layer may be the same or different, and the type of thermosetting resin depends on the functions and functions each layer should have. It may be selected appropriately depending on physical properties and the like. For example, from the viewpoint of having excellent chemical resistance, the layer forming the outermost layer (the outermost layer located on the opposite side to the base material layer 1 side) among the layers constituting the surface coating layer is polycyclic. Thermosetting resins having an aromatic skeleton and/or a heterocyclic skeleton are preferably used. Specific examples of the thermosetting resin having a polycyclic aromatic skeleton include epoxy resins having a polycyclic aromatic skeleton and urethane resins having a polycyclic aromatic skeleton. Further, specific examples of the thermosetting resin having a heterocyclic skeleton include amino resins such as melamine resin and benzoguanamine resin. These thermosetting resins having a polycyclic aromatic skeleton and/or a heterocyclic skeleton may be either a one-component curing type or a two-component curing type.

More specifically, the epoxy resin having a polycyclic aromatic skeleton includes a reaction product of dihydroxynaphthalene and epihalohydrin; a reaction product of a condensation product of naphthol and aldehydes (naphthol novolac resin) and epihalohydrin; dihydroxy A reaction product of a condensation product of naphthalene and aldehydes and an epihalohydrin; a reaction product of a condensation product of mono- or dihydroxynaphthalene and xylylene glycols and a reaction product with epihalohydrin; an adduct of a mono- or dihydroxynaphthalene and a diene compound; Reaction products with epihalohydrin; Reaction products with epihalohydrin and polynaphthols in which naphthols are directly coupled to each other.

More specifically, the urethane resin having a polycyclic aromatic skeleton includes a reaction product of a polyol compound and an isocyanate compound having a polycyclic aromatic skeleton.

(hardening accelerator)
The resin composition forming the surface coating layer may further contain a curing accelerator in addition to the resin components described above. By coexisting a curing accelerator with a thermosetting resin, the surface coating layer can be cured in a short time without requiring aging under high temperature conditions during production, and a layer having a specific hardness can be formed.

Here, "curing accelerator" is a substance that does not form a crosslinked structure by itself, but promotes the crosslinking reaction of thermosetting resin, has the effect of promoting the crosslinking reaction of thermosetting resin, and has the effect of promoting the crosslinking reaction of thermosetting resin. It is also a substance that may form a crosslinked structure.

The type of curing accelerator is appropriately selected depending on the thermosetting resin used so as to satisfy the hardness described above. For example, amidine compounds, carbodiimide compounds, ketimine compounds, hydrazine compounds, sulfonium salts, benzene Examples include thiazolium salts and tertiary amine compounds.

Amidine compounds are not particularly limited, but include, for example, imidazole compounds, 1,8-diazabicyclo[5.4.0]undec-7ene (DBU), 1,5-diazabicyclo[4.3.0]none-5- Examples include carbon dioxide (DBN) and guanidine compounds. Specific examples of imidazole compounds include 2-methylimidazole, 2-ethylimidazole, 2-undecylimidazole, 2,4-dimethylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 1,2- Diethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-benzyl-2 -Methylimidazole, 2,4-diamino-6-[2'-methylimidazolyl-(1)']-ethyl-S-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl -(1)']-ethyl-S-triazine, 2,4-diamino-6-[2'-undecylimidazolyl]-ethyl-S-triazine, 2,4-diamino-6-[2'-methylimidazolyl -(1)']-ethyl-S-triazine isocyanuric acid adduct, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2-aryl-4, Examples include 5-diphenylimidazole. These amidine compounds may be used alone or in combination of two or more.

Carbodiimide compounds are not particularly limited, but include, for example, N,N'-dicyclohexylcarbodiimide, N,N'-diisopropylcarbodiimide, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, N-[3-(dimethylaminopropyl)carbodiimide, ) propyl]-N'-ethylcarbodiimide, N-[3-(dimethylamino)propyl]-N'-ethylcarbodiimide methiodide, N-tert-butyl-N'-ethylcarbodiimide, N-cyclohexyl-N'- Examples include (2-morpholinoethyl)carbodiimide meso-p-toluenesulfonate, N,N'-di-tert-butylcarbodiimide, and N,N'-di-p-tolylcarbodiimide. These carbodiimide compounds may be used alone or in combination of two or more.

The ketimine compound is not particularly limited as long as it has a ketimine bond (N=C), but examples include ketimine compounds obtained by reacting a ketone and an amine. Specific examples of the ketone include methyl ethyl ketone, methyl isopropyl ketone, methyl tert-butyl ketone, methyl cyclohexyl ketone, diethyl ketone, ethyl propyl ketone, ethyl butyl ketone, dipropyl ketone, dibutyl ketone, diisobutyl ketone, and the like. . In addition, specific examples of the amine include aromatic polyamines such as o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, m-xylylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, and diaminodiethyldiphenylmethane; Ethylenediamine, propylenediamine, butylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, hexamethylenediamine, trimethylhexamethylenediamine, 1,2-propanediamine, iminobispropylamine, methyliminobispropylamine, etc. aliphatic polyamines; monoamines with ether bonds in the main chain such as N-aminoethylpiperazine and 3-butoxyisopropylamine; diamines with a polyether skeleton; isophoronediamine, 1,3-bisaminomethylcyclohexane, 1-cyclohexylamino- Alicyclic polyamines such as 3-aminopropane and 3-aminomethyl-3,3,5-trimethylcyclohexylamine; diamines with a norbornane skeleton; polyamide amines having an amino group at the end of the polyamide molecule; 2,5-dimethyl-2 , 5-hexamethylenediamine, menzendiamine, and 1,4-bis(2-amino-2-methylpropyl)piperazine. These ketimine compounds may be used alone or in combination of two or more.

The hydrazine compound is not particularly limited, but includes, for example, dipic acid dihydrazide, isophthalic acid dihydrazide, and the like. These hydrazine compounds may be used alone or in combination of two or more.

Sulfonium salts are not particularly limited, but include, for example, 4-acetophenyldimethylsulfonium hexafluoroantimonate, 4-acetophenyldimethylsulfonium hexafluoroarsenate, dimethyl-4-(benzyloxycarbonyloxy)phenylsulfonium hexafluoroantimonate, Alkylsulfonium salts such as dimethyl-4-(benzoyloxy)phenylsulfonium hexafluoroantimonate, dimethyl-4-(benzoyloxy)phenylsulfonium hexafluoroarsenate; benzyl-4-hydroxyphenylmethylsulfonium hexafluoroantimonate, 4- Acetoxyphenylbenzylmethylsulfonium hexafluoroantimonate, benzyl-4-methoxyphenylmethylsulfonium hexafluoroantimonate, benzyl-3-chloro-4-hydroxyphenylmethylsulfonium hexafluoroarsenate, 4-methoxybenzyl-4-hydroxyphenylmethyl Benzylsulfonium salts such as sulfonium hexafluorophosphate; dibenzyl-4-hydroxyphenylsulfonium hexafluoroantimonate, dibenzyl-4-hydroxyphenylsulfonium hexafluorophosphate, dibenzyl-4-methoxyphenylsulfonium hexafluorantimonate, benzyl-4-methoxy Dibenzylsulfonium salts such as benzyl-4-hydroxyphenylsulfonium hexafluorophosphate; p-chlorobenzyl-4-hydroxyphenylmethylsulfonium hexafluoroantimonate, p-nitrobenzyl-4-hydroxyphenylmethylsulfonium hexafluoroantimonate, 3 , 5-dichlorobenzyl-4-hydroxyphenylmethylsulfonium hexafluoroantimonate, o-chlorobenzyl-3-chloro-4-hydroxyphenylmethylsulfonium hexafluoroantimonate, and other substituted benzylsulfonium salts. These sulfonium salts may be used alone or in combination of two or more.

Benzothiazolium salts are not particularly limited, but include, for example, 3-benzylbenzothiazolium hexafluoroantimonate, 3-benzylbenzothiazolium hexafluorophosphate, 3-benzylbenzothiazolium tetrafluoroborate, and 3-benzothiazolium hexafluoroantimonate. Benzylbenzos such as (p-methoxybenzyl)benzothiazolium hexafluoroantimonate, 3-benzyl-2-methylthiobenzothiazolium hexafluoroantimonate, 3-benzyl-5-chlorobenzothiazolium hexafluoroantimonate, etc. Examples include thiazolium salts. These benzothiazolium salts may be used alone or in combination of two or more.

Tertiary amine compounds are not particularly limited, but include fats such as trimethylamine, triethylamine, tripropylamine, tributylamine, triethylenediamine, 1,4-diazabicyclo[2.2.2]octane, quinuclidine, and 3-quinuclidinol. aromatic tertiary amines such as dimethylaniline; heterocyclic tertiary amines such as isoquinoline, pyridine, collidine, and betapicoline. These tertiary amine compounds may be used alone or in combination of two or more.

A suitable example of the curing accelerator is one that functions as a thermal acid generator. A thermal acid generator is a substance that generates acid upon heating and functions as a curing accelerator. Among the curing accelerators mentioned above, those that can function as thermal acid generators include sulfonium salts, benzothiazolium salts, and the like.

Another suitable example of the curing accelerator is a thermal latent agent that activates under predetermined heating conditions (for example, 80 to 200°C, preferably 100 to 160°C) to promote the crosslinking reaction of the thermosetting resin. Examples include those with the following. Among the above-mentioned curing accelerators, examples of heat-latent substances include epoxy adducts in which an epoxy compound is added to an amidine compound, a hydrazine compound, a tertiary amine compound, or the like.

Furthermore, another suitable example of the curing accelerator is that it does not function as a curing agent in a sealed state, that is, in a moisture-blocking state, but when the sealed state is opened and hydrolyzed in the presence of moisture, it acts as a curing agent. Examples include those with functional hydrolytic latent properties. Among the above-mentioned curing accelerators, specific examples of hydrolyzable latent substances include epoxy adducts in which an epoxy compound is added to an amidine compound, a hydrazine compound, a tertiary amine compound, or the like.

These curing accelerators may be used alone or in combination of two or more. Among these curing accelerators, amidine compounds and sulfonium salts are preferred, and amidine compounds are more preferred.

These curing accelerators may be used alone or in combination of two or more in the surface coating layer. In addition, when the surface coating layer is formed of multiple layers, the curing accelerator used in each layer constituting the surface coating layer may be the same or different, and the type of curing accelerator may be , may be selected as appropriate depending on the functions and physical properties to be provided in each layer.

When using a curing accelerator, the content of the curing accelerator in the resin composition used to form the surface coating layer is appropriately set depending on the type of thermosetting resin used, the type of curing accelerator, etc. However, for example, the total amount of the curing accelerator is about 0.01 to 6 parts by weight, preferably about 0.05 to 5 parts by weight, and more preferably 0.1 to 2 parts by weight, based on 100 parts by weight of the thermosetting resin. Examples include parts by mass.

It is preferable that the surface coating layer contains a filler as an additive. That is, the surface coating layer is preferably formed from a resin composition containing a filler. When the surface coating layer contains the filler, an uneven shape can be formed on the surface of the surface coating layer, and a matte feel can be imparted to the battery packaging material. Specific examples of fillers include inorganic fillers such as titanium oxide, silica, talc, clay, heavy calcium carbonate, light calcium carbonate, barium sulfate, calcium silicate, synthetic silicates, aluminum hydroxide, and fine silicate powder. Can be mentioned. Only one type of filler may be used, or a mixture of two or more types may be used.

Among inorganic fillers, inorganic fillers made of silica or precipitated barium sulfate are preferred because they are easy to handle and easily available. Note that precipitated barium sulfate refers to barium sulfate produced using a chemical reaction, and is characterized by the ability to control the particle size.

The content of the filler in the surface coating layer is preferably about 2.0 to 8.7% by mass, for example, when the filler is silica with an average particle diameter of about 1.0 to 3.0 μm, and For example, when the filler is precipitated barium sulfate with an average particle diameter of less than 1.5 μm, the content is preferably about 13.0 to 40.0% by mass. The content of the filler is the content of the filler in the surface coating layer, and is the content after the solvent has evaporated from the above-mentioned resin composition for forming the surface coating layer containing the filler. Note that the average particle diameter of the filler is the median diameter measured by a laser diffraction/scattering particle size distribution measuring device.

The surface coating layer may contain at least one of a pigment and a dye as an additive. When the surface coating layer contains at least one of a pigment and a dye, whitening during molding can be more effectively suppressed, and wear resistance can also be improved. Further, since the surface coating layer contains at least one of a pigment and a dye, the battery packaging material of the present invention can be given distinctiveness (colored by at least one of the pigment and the dye). It becomes possible to impart a matte design to the surface of the battery packaging material of the present invention, and to further increase the thermal conductivity of the battery packaging material of the present invention to improve heat dissipation.

The material of the pigment is not particularly limited, and may be either an inorganic pigment or an organic pigment. Specifically, the above-mentioned inorganic pigments include carbon black, carbon nanotubes, graphite, kaolin, magnesium hydroxide, zinc oxide, magnesium oxide, aluminum oxide, neodymium oxide, antimony oxide, cerium oxide, calcium sulfate, lithium carbonate, gold , aluminum, copper, nickel, etc. Specific examples of the organic pigment include azo pigments, polycyclic pigments, lake pigments, and fluorescent pigments. These pigments may be used alone or in combination of two or more.

The shape of the pigment is not particularly limited either, and examples include spherical, fibrous, plate-like, amorphous, and balloon-like shapes. Further, the average particle diameter of the pigment is not particularly limited, but for example, it is preferably about 0.01 to 3 μm, more preferably about 0.05 to 1 μm. Note that the average particle diameter of the pigment is the median diameter measured by a laser diffraction/scattering particle diameter distribution measuring device.

The pigment may be subjected to various surface treatments, such as insulation treatment and high dispersion treatment (resin coating treatment), as required.

The type of dye is not particularly limited as long as it can be dissolved and dispersed in the resin composition used to form the surface coating layer, but examples include nitro dyes, azo dyes, stilbene dyes, carponium dyes, and quinoline dyes. , methine dyes, thiazole dyes, quinimine dyes, anthraquinone dyes, indigoid dyes, and phthalocyanine dyes, preferably azo dyes, carponium dyes, anthraquinone dyes, and the like. These dyes may be used alone or in combination of two or more.

Among these pigments and dyes, from the viewpoint of further improving the heat dissipation properties of the battery packaging material of the present invention, pigments are preferred, more preferably inorganic pigments, and still more preferably carbons such as carbon black, carbon nanotubes, and graphite. Materials, particularly preferably carbon black.

When the surface coating layer has a multilayer structure composed of two or more layers, the pigment and/or dye must be added to any one of these two or more layers in order to contain the above-mentioned pigment, etc. It may be contained in a layer, or it may be contained in two or more layers. After molding the battery packaging material of the present invention, from the viewpoint of reducing the difference in color tone between the molded part and the unmolded part, the surface coating layer is formed into a multilayer structure composed of two or more layers. It is preferable that two or more layers contain pigments and/or dyes, and it is further preferable that the surface coating layer has a three-layer structure composed of three layers and that all three layers contain pigments and/or dyes. preferable.

When a pigment and/or dye is contained in at least one layer constituting the surface coating layer, the content should be determined based on the type of pigment and/or dye used and the identification to be given to the battery packaging material of the present invention. For example, the total amount of pigment and/or dye may be 1 to 30 parts by mass per 100 parts by mass of the resin component contained in the layer containing pigment and/or dye. An example of this is the degree. From the viewpoint of imparting even better identifiability, the total amount of pigments and/or dyes may be about 3 to 20 parts by mass based on 100 parts by mass of the resin component contained in the layer containing the pigments and/or dyes. It will be done. In addition, from the viewpoint of suppressing deterioration in moldability caused by pigments and/or dyes as well as even better identification, based on 100 parts by mass of the resin component contained in the layer containing pigments and/or dyes, The total amount of pigment and/or dye may be about 5 to 15 parts by mass.

In addition to the above-mentioned additives, the resin composition used for forming the surface coating layer may contain organic fillers, lubricants, solvents, Other additives such as elastomeric resins may also be included.

When the surface coating layer contains an organic filler or a lubricant as an additive, it imparts a slip effect to the surface of the battery packaging material of the present invention, improves moldability and processability in press molding and embossing, and improves operability. can be improved.

The type of organic filler is not particularly limited, but examples thereof include high melting point nylon, crosslinked acrylic, crosslinked styrene, crosslinked polyethylene, and benzoguanamine. Further, the shape of the organic filler is not particularly limited, and examples thereof include spherical, fibrous, plate-like, amorphous, and balloon-like shapes.

Further, the lubricant is not particularly limited, and may be, for example, a non-reactive lubricant or a reactive lubricant. In particular, reactive lubricants have the advantage that they are difficult to bleed and lose from the outermost layer constituting the surface coating layer, and can suppress powder blowing and set-off during use, as well as a decline in the slip effect over time. Therefore, among the lubricants, reactive lubricants are preferable.

Here, the non-reactive lubricant is, for example, a compound that does not have a functional group that reacts and chemically bonds with the resin component described above and can impart slip properties. In addition, the reactive lubricant is a compound that has a functional group that reacts with the resin component and chemically bonds with it, and that can impart slip properties.

Specific examples of non-reactive lubricants include fatty acid amide, metal soap, hydrophilic silicone, acrylic grafted with silicone, epoxy grafted with silicone, polyether grafted with silicone, polyester grafted with silicone, and blocks. Examples include type silicone acrylic copolymers, polyglycerol-modified silicones, and paraffins. These non-reactive lubricants may be used alone or in combination of two or more.

In addition, the type of functional group in the reactive lubricant is appropriately set depending on the type of resin component used, but examples include hydroxyl group, mercapto group, hydrolyzable silyl group, isocyanate group, epoxy group, polymerizable Examples include vinyl group and (meth)acryloyl group. In the reactive lubricant, the number of functional groups per molecule is not particularly limited, but may be, for example, 1 to 3, preferably 1 or 2.

Specifically, reactive lubricants include modified silicones having the above functional groups; modified fluororesins having the above functional groups; and fatty acid amides such as stearamide, oleic acid amide, erucic acid amide, and ethylene bisstearic acid amide. Examples include compounds into which the above-mentioned functional groups have been introduced; metal soaps into which the above-mentioned functional groups have been introduced; and paraffins into which the above-mentioned functional groups have been introduced. These reactive lubricants may be used alone or in combination of two or more. Among these reactive lubricants, preferred are modified silicones having the aforementioned functional groups, modified fluororesins having the aforementioned functional groups, and silicone modified resins having the aforementioned functional groups. Specifically, the modified silicone includes, for example, a modified silicone in which a polymer having the above-mentioned functional group is block-polymerized, such as a modified silicone in which an acrylic resin is block-polymerized; a modified silicone in which an acrylate is graft-polymerized; Examples include modified silicones in which monomers having the aforementioned functional groups are graft-polymerized. In addition, modified fluororesins include, for example, modified fluororesins in which monomers having the functional groups are graft-polymerized, such as fluororesins in which acrylates are graft-polymerized; modified fluororesins in which acrylic resins are block-polymerized; Examples include fluororesins in which polymers having the aforementioned functional groups are block-polymerized, such as fluororesins. In addition, the silicone-modified resin specifically includes a silicone-modified acrylic resin that has the above-mentioned functional group and is graft-polymerized with silicone, such as a silicone-modified acrylic resin that has the above-mentioned functional group and is graft-polymerized with silicone. Examples include modified resins. Among these, particularly preferred reactive lubricants include modified silicones in which a monomer or polymer having the above-mentioned functional group is polymerized at one end of silicone; Examples include modified fluororesins that are polymerized at one end of the fluororesin. Such modified silicones and modified fluororesins are commercially available, such as the "Modiper (registered trademark) F/FS series" (manufactured by NOF Corporation) and the "Cymac (registered trademark) series" (manufactured by Toagosei Co., Ltd.). These commercially available products can also be used.

When a lubricant is contained in the resin composition used to form the outermost layer in the surface coating layer, the content is not particularly limited, but for example, the lubricant is added to 100 parts by mass of the resin component. The total amount is about 1 to 12 parts by weight, preferably about 3 to 10 parts by weight, and more preferably about 5 to 8 parts by weight.

Other specific examples of additives include montmorilloid, montmorillonite, synthetic mica, hydrotalcite, zeolite, calcium benzoate, calcium oxalate, magnesium stearate, gold, aluminum, copper, and nickel.

The method for forming the surface coating layer is not particularly limited, but includes, for example, a method of applying a resin composition for forming the surface coating layer onto one surface of the base layer 1. When adding additives, the additives may be added to the resin composition, mixed, and then applied.

The thickness of the surface coating layer is not particularly limited as long as it exhibits the above-mentioned function as a surface coating layer, but may be, for example, about 0.5 to 10 μm, preferably about 1 to 5 μm.

3. Method for manufacturing battery packaging material The method for manufacturing battery packaging material is not particularly limited as long as a laminate in which layers having a predetermined composition are laminated can be obtained. That is, the battery packaging material includes at least a step of laminating a base material layer, a barrier layer, and a heat-fusible resin layer in this order, and the base material layer has the above-mentioned slope ratio S _TD/ It can be manufactured using a polyethylene terephthalate film having _{an MD} of 0.8 or more.

An example of the method for manufacturing the battery packaging material of the present invention is as follows. First, a laminate (hereinafter sometimes 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 formation of the laminate A is performed by applying the adhesive used for forming the adhesive layer 2 on the base layer 1 or on the barrier layer 3 whose surface has been subjected to a chemical conversion treatment as necessary, using a gravure coating method, It can be carried out by a dry lamination method in which the barrier layer 3 or base material layer 1 is laminated and the adhesive layer 2 is cured after coating and drying by a coating method such as a roll coating method.

Next, a heat-fusible resin layer 4 is laminated on the barrier layer 3 of the laminate A. When directly laminating the heat-fusible resin layer 4 on the barrier layer 3, the resin component constituting the heat-fusible resin layer 4 is coated on the barrier layer 3 of the laminate A by gravure coating or roll coating. It may be applied by a method such as In addition, when providing the adhesive layer 5 between the barrier layer 3 and the heat-fusible resin layer 4, for example, (1) the adhesive layer 5 and the heat-fusible resin layer are provided on the barrier layer 3 of the laminate A. (2) Separately, a laminate is formed by laminating the adhesive layer 5 and the heat-fusible resin layer 4, and this is used as the barrier layer of the laminate A. (3) Extrusion method or solution coating of an adhesive to form the adhesive layer 5 on the barrier layer 3 of the laminate A, followed by drying at high temperature and baking. (4) The barrier layer 3 of the laminate A and the barrier layer 3 of the laminate A are laminated on the adhesive layer 5, and the heat-fusible resin layer 4, which has been formed into a sheet in advance, is laminated by the thermal lamination method. A method of laminating the laminate A and the heat-fusible resin layer 4 via the adhesive layer 5 while pouring the melted adhesive layer 5 between the filmed heat-fusible resin layer 4 (sandwich lamination method) Examples include.

When providing a surface coating layer, the surface coating layer is laminated on the surface of the base layer 1 opposite to the barrier layer 3 . The surface coating layer can be formed, for example, by applying the above-mentioned resin that forms the surface coating layer onto the surface of the base layer 1. Note that 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 forming a surface coating layer 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 coating layer.

As described above, a surface coating layer provided as necessary/base material layer 1/adhesive layer 2 provided as necessary/barrier layer 3 whose surface has been chemically treated as necessary/ A laminate consisting of the provided adhesive layer 5/heat-fusible resin layer 4 is formed, but in order to strengthen the adhesiveness of the provided adhesive layer 2 and adhesive layer 5, if necessary, heat may be further applied. It may be subjected to heat treatment such as roll contact type, hot air type, near infrared type or far infrared type. Conditions for such heat treatment include, for example, 150 to 250° C. for 1 to 5 minutes.

In battery packaging materials, each layer constituting the laminate may be coated as necessary to improve or stabilize film formability, lamination processing, suitability for secondary processing of final products (pouching, embossing), etc. Surface activation treatments such as corona treatment, blasting treatment, oxidation treatment, and ozone treatment may be performed. For example, by subjecting at least one surface of the base material layer to corona treatment, film formability, lamination processing, suitability for secondary processing of the final product, etc. can be improved or stabilized. Furthermore, for example, by subjecting the surface of the base layer 1 opposite to the barrier layer 3 to a corona treatment, the printability of the ink on the surface of the base layer 1 can be improved.

4. Applications of Battery Packaging Materials Battery packaging materials are used as packages for sealing and accommodating battery elements such as positive electrodes, negative electrodes, and electrolytes. That is, a battery can be obtained by accommodating a battery element including at least a positive electrode, a negative electrode, and an electrolyte in a package formed of a battery packaging material. In the battery packaging material, a space for accommodating a battery element is formed, for example, by cold forming or the like, and becomes a package.

Specifically, a battery element comprising at least a positive electrode, a negative electrode, and an electrolyte is packaged using the battery packaging material of the present invention, with metal terminals connected to each of the positive electrode and negative electrode protruding outward. By coating the element so that a flange part (an area where the heat-fusible resin layers contact each other) is formed around the periphery of the element, and heat-sealing the heat-fusible resin layers of the flange part to each other, the battery is sealed. A battery using the packaging material is provided. In addition, when a battery element is housed in a package formed of the battery packaging material of the present invention, the sealant part of the battery packaging material of the present invention is on the inside (the surface in contact with the battery element). form the body.

The battery packaging material may be used for either a primary battery or a secondary battery, but is preferably used for a secondary battery. The types of secondary batteries to which the battery packaging material of the present invention is applied are not particularly limited, and examples include lithium-ion batteries, lithium-ion polymer batteries, lead-acid batteries, nickel-hydrogen batteries, nickel-cadmium batteries, and nickel-cadmium batteries. Examples include iron storage batteries, nickel/zinc storage batteries, silver oxide/zinc oxide storage batteries, metal-air batteries, polyvalent cation batteries, capacitors, and capacitors. Among these secondary batteries, lithium ion batteries and lithium ion polymer batteries are suitable for application of the battery packaging material of the present invention.

The present invention will be explained in detail by showing Examples and Comparative Examples below. However, the present invention is not limited to the examples.

(Examples 1 to 6 and Comparative Example 1)
In Examples 1 to 6 and Comparative Example 1, the measurement of the slope of the straight line connecting the yield point and the breaking point in the tensile test of polyethylene terephthalate film (PET film), the difference in heat of fusion ΔH _1-2 , and the measurement of the battery packaging material. The moldability was evaluated as follows. The results are shown in Table 1.

(Measurement of the slope of the straight line connecting the yield point and fracture point by tensile test)
Obtain a stress-strain curve that shows the relationship between the stress (MPa) applied to the polyethylene terephthalate film and the strain (elongation (%)) measured by a tensile test, and calculate the yield point and fracture from the graph. The slope of the straight line connecting the points was measured, and the ratio S _TD/MD of the slope S _TD in the TD direction of the polyethylene terephthalate film to the slope S _MD in the MD direction of the polyethylene terephthalate film was calculated. The specific measurement conditions are as follows. A sample of PET film was cut out to a size of 100 mm x 15 mm so that the long sides were in the MD direction and the TD direction. A Tensilon universal material testing machine RTG-1210 manufactured by A&D Co., Ltd. was used as a tensile tester, and the sample was pulled at a distance between chucks of 50 mm and a tensile speed of 300 mm/min to obtain a stress-strain curve. The tensile tests in the MD direction and the TD direction were conducted on 30 similarly prepared samples, and the yield point and fracture point were determined from the top five stress-strain curves in descending order of strain (elongation). Measure the slopes S _MD and S _TD of the connecting straight lines, calculate the slope ratio S TD/MD from the average value of the five slopes S _MD and the average value of the five slopes S _TD , and calculate the slope ratio S _{TD /} The true value of _MD was determined. This is because it can be said that the larger the strain in the sample, the more appropriate the condition of the fractured surface at the time of sample preparation, and the less formed creases that would affect the measurement results. The slopes S _MD and S _TD of the straight line connecting the yield point and the breaking point can be expressed by the following formulas, respectively.
Slope of the straight line connecting the yield point and the fracture point S _MD = {(Tensile fracture stress in the direction of MD) - (Tensile yield stress in the direction of MD)}/{(Tensile fracture strain in the direction of MD) - (Tensile fracture stress in the direction of MD) tensile yield strain in the direction)}
Slope of the straight line connecting the yield point and the fracture point S _TD = {(Tensile fracture stress in the direction of TD) - (Tensile yield stress in the direction of TD)}/{(Tensile fracture strain in the direction of TD) - (Tensile fracture stress in the direction of TD) tensile yield strain in the direction)}

Measured values of tensile yield stress (MPa) and tensile fracture stress (MPa) in the MD direction and TD direction at the yield point and fracture point by a tensile test, as well as tensile yield strain (%) and tensile fracture strain (%), Table 2 shows the absolute value of the difference between the TD direction and the MD direction (|TD−MD|) of these measured values.

(Measurement of heat of fusion difference ΔH _1-2 )
Using a differential scanning calorimeter, heat of fusion H ₁ is measured for the first time after heating from 0 °C to 300 °C at a heating rate of 10 °C / min, and after measuring the heat of fusion H ₁ , After cooling from a temperature of 300°C to a temperature of 0°C at a temperature decreasing rate of 10°C/min, the heat of fusion H is measured for the second time by heating from a temperature of 0°C to a temperature of 300°C at a temperature increasing rate of 10°C/min. The difference in heat _{of fusion ΔH 1-2 was} measured. The specific measurement conditions are as follows. "DSC-60 Plus" manufactured by Shimadzu Corporation was used as a differential scanning calorimeter, and TA60 manufactured by Shimadzu Corporation was used as analysis software. Moreover, an aluminum pan was used as a sample pan. In addition, the measurement was carried out after setting the PET film sample in the device, cooling it from room temperature to 0°C at a rate of 10°C/min under a nitrogen atmosphere, holding it at 0°C for 15 minutes, and cooling it at a rate of 10°C/min under a nitrogen atmosphere. It was heated up to 300°C at high speed. The endothermic peak appearing at this time was defined as melting peak 1, and the heat of fusion was defined as _H1 . Next, after heating to 300°C, it was held at 300°C for 1 minute, and then cooled again to 0°C at a rate of 10°C/min. Once the temperature reached 0°C, it was held for 1 minute, and then heated to 300°C again. The endothermic peak appearing at this time was defined as melting peak 2, and similarly to the heat of fusion _H1 , the heat of fusion was defined as _H2 . The difference (H ₁ - _{H 2} ) between the two obtained heats of fusion was taken and defined as the difference in heat of fusion ΔH _1-2 . In each graph obtained by measurement using a differential scanning calorimeter, each heat of fusion is determined by the baseline value that existed between 180°C and 200°C before the transition, as explained using the schematic diagram in Figure 5 above. The area of the region surrounded by a straight line connecting the point away from 260°C and the point that returned to the baseline after transition, which existed between 260°C and 280°C, and the line where the endothermic peak exists The heat of fusion (heat of transition) was calculated from

(Evaluation of moldability of battery packaging material A)
A sample is prepared by cutting a battery packaging material A, which will be described later, into a rectangle of 90 mm (MD) x 150 mm (TD) using a laminate of a PET film and a biaxially stretched nylon film as a base material layer. This sample was molded into a mold having a diameter of 32 mm (MD) x 54 mm (TD) (the female mold surface is specified in Table 2 of JIS B 0659-1: 2002 Annex 1 (reference) Comparison Surface Roughness Standard Piece). The maximum height roughness (nominal value of Rz) is 3.2 μm) and the molding mold corresponding to this (the male mold surface is JIS B 0659-1:2002 Annex 1 (reference) for comparison) Using the maximum height roughness (nominal value of Rz) specified in Table 2 of the surface roughness standard piece, which is 1.6 μm, the surface roughness was measured from a molding depth of 0.5 mm at a pressing pressure of 0.9 MPa. Cold forming is performed on 20 samples each, changing the forming depth in 5 mm increments. Regarding samples after cold forming, Amm is the deepest forming depth at which pinholes or cracks do not occur in the aluminum foil in all 20 samples, and Amm is the deepest forming depth at which pinholes or cracks do not occur in the aluminum foil. Let B be the number of samples in which .
Molding depth of battery packaging material A = Amm + (0.5 mm/20 pieces) x (20 pieces - B pieces)

(Evaluation of moldability of battery packaging material B)
A sample is prepared by cutting a battery packaging material B described below using a PET film as a base layer into a rectangle of 90 mm (MD) x 150 mm (TD). This sample was molded into a mold having a diameter of 32 mm (MD) x 54 mm (TD) (the female mold surface is specified in Table 2 of JIS B 0659-1: 2002 Annex 1 (reference) Comparison Surface Roughness Standard Piece). The maximum height roughness (nominal value of Rz) is 3.2 μm) and the molding mold corresponding to this (the male mold surface is JIS B 0659-1:2002 Annex 1 (reference) for comparison) Using the maximum height roughness (nominal value of Rz) specified in Table 2 of the surface roughness standard piece, which is 1.6 μm, the surface roughness was measured from a molding depth of 0.5 mm at a pressing pressure of 0.4 MPa. Cold forming is performed on 20 samples each, changing the forming depth in 5 mm increments. Regarding samples after cold forming, Cmm is the deepest forming depth at which no pinholes or cracks occur in the aluminum foil in all 20 samples, and Cmm is the deepest forming depth at which pinholes or cracks do not occur in the aluminum foil. Let D be the number of samples in which this occurs, and let the value calculated by the following formula be the molding depth of the battery packaging material B.
Molding depth of battery packaging material B = Cmm + (0.5mm/20 pieces) x (20 pieces - D pieces)

(Manufacture of battery packaging material A)
As a barrier layer, an aluminum foil (thickness: 40 μm) was prepared, which was chemically treated (phosphoric acid chromate treatment) on both sides with a chemical conversion treatment liquid consisting of three components: phenol resin, fluoride chromium (trivalent) compound, and phosphoric acid. In addition, each polyethylene terephthalate film (PET, thickness 12 μm) having the slope ratio S _TD/MD and the heat of fusion difference ΔH _1-2 shown in Table 1 was prepared. Next, each polyethylene terephthalate film and a biaxially stretched nylon film (Ny, thickness 15 μm) were laminated via a urethane adhesive (thickness after curing was 1 μm) to form a base layer. The nylon film side surface of the base material layer and one surface of the barrier layer are laminated via a urethane adhesive (thickness after curing is 1 μm), and the base material layer/adhesive layer/barrier layer A laminate in which the layers were stacked in order was obtained. Next, maleic anhydride-modified polypropylene (thickness 20 μm) as an adhesive layer and polypropylene (thickness 15 μm) as a heat-fusible resin layer were coextruded onto the barrier layer side surface of the obtained laminate. By laminating, a laminate in which the base material layer (PET/Ny)/adhesive layer/barrier layer/adhesive layer/thermal adhesive resin layer was laminated in this order was obtained, which was designated as battery packaging material A. .

(Manufacture of battery packaging material B)
As a barrier layer, an aluminum foil (thickness: 40 μm) was prepared, which was chemically treated (phosphoric acid chromate treatment) on both sides with a chemical conversion treatment liquid consisting of three components: phenol resin, fluoride chromium (trivalent) compound, and phosphoric acid. Further, each polyethylene terephthalate film (PET, thickness 12 μm) having the slope ratio S _TD/MD and the heat of fusion difference ΔH _1-2 shown in Table 1 was prepared and used as a base layer. One side of the base layer and one side of the barrier layer are laminated via a urethane adhesive (thickness after curing is 1 μm), and the base layer/adhesive layer/barrier layer are laminated in this order. A laminate was obtained. Next, maleic anhydride-modified polypropylene (thickness 20 μm) as an adhesive layer and polypropylene (thickness 15 μm) as a heat-fusible resin layer were coextruded onto the barrier layer side surface of the obtained laminate. By laminating, a laminate in which base material layer (PET)/adhesive layer/barrier layer/adhesive layer/thermal adhesive resin layer was laminated in this order was obtained, and this was used as battery packaging material B.

In Table 1, PET means polyethylene terephthalate film, and Ny means biaxially stretched nylon film.

In the battery packaging materials of Examples 1 to 6, a polyethylene terephthalate film having the slope ratio S _TD/MD of 0.8 or more is used as the base layer, and exhibits excellent moldability. I understand that. Further, when comparing examples with similar values of the heat of fusion difference ΔH _1-2 , it can be seen that examples with a slope ratio S _TD/MD close to 1 have better moldability. That is, when Example 3 and Example 4 are compared, Example 3 has better moldability, and when Example 2 and Example 5 are compared, Example 5 has better moldability. Further, in Example 6, the difference in heat of fusion ΔH _1-2 is as small as 6 J/g, but the value of the slope ratio S _TD/MD is close to 1, and the moldability is excellent.

11 Polyethylene terephthalate film 12 Adhesive layer 13 Polyamide film 1 Base layer 2 Adhesive layer 3 Barrier layer 4 Heat-fusible resin layer 5 Adhesive layer 10 Battery packaging material

Claims (1)

A polyethylene terephthalate film used for the base layer of a battery packaging material comprising a base layer, a barrier layer, and a heat-fusible resin layer in this order,
In the stress-strain curve showing the relationship between the stress (MPa) applied to the polyethylene terephthalate film and the strain at that time, measured by a tensile test under the conditions of an inter-chuck distance of 50 mm and a tensile speed of 300 mm/min, When measuring the slope of a straight line connecting the yield point and the breaking point, the ratio S _TD of the slope S _TD in the TD direction of the polyethylene terephthalate film to the slope S MD in the MD direction of the polyethylene terephthalate film S _TD/MD is 0.8 or more, a polyethylene terephthalate film for battery packaging material.