JP2014024962A - Adhesive, and adhesive-used outer packaging material for battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive which is used in an outer packaging material for batteries, that material is subjected to a drawing process, and which can suppress the generation of delamination between a base material film and a metal foil sheet even under a high-temperature and high-humidity environment.SOLUTION: An adhesive 12 is used in an outer packaging material 10 for batteries, which material includes a base material film 11 and a metal foil sheet 13, when the base material film 11 is stuck to the metal foil sheet 13. The adhesive 12 is characterized in that a displacement rate is less than 3% at 80°C when needle penetration of thermomechanical analysis is measured.

Description

  The present invention relates to an adhesive used for a battery outer packaging material including a base film and a metal foil, and bonds the base film and the metal foil.

Conventionally, as a package of a lithium ion battery, a battery outer packaging material obtained by bonding a base film and a metal foil with an adhesive is used. Due to their characteristics, lithium ion batteries are mounted on, for example, mobile phones and automobiles, and are sometimes placed in high-temperature and high-humidity environments. For this reason, excellent durability is also required as a battery outer packaging material. For example, in Patent Document 1, a nylon film as a base film is subjected to drawing processing by setting the density of the nylon film to 1130 kg / m ³ or more. Discloses a battery packaging material in which delamination does not occur between the base film and the metal foil even when stored in a dryer at 80 ° C. for 3 hours.

JP 2008-288117 A

  However, Patent Document 1 only describes the test results in the dryer, and since nylon films are generally susceptible to humidity, the battery packaging material of Patent Document 1 is used in a high-temperature and high-humidity environment. It did not suppress the occurrence of delamination between the base film and the metal foil.

  Therefore, the present invention provides an adhesive that can suppress the occurrence of delamination between a base film and a metal foil even in a high-temperature and high-humidity environment in a drawn battery outer packaging material. The purpose is to provide.

  The adhesive according to the present invention is an adhesive for bonding a base film and a metal foil, which is used in a battery outer packaging material including a base film and a metal foil, and at 80 ° C. by penetration measurement of thermomechanical analysis. The displacement rate is less than 3%.

  According to such a structure, in order to suppress the deformation | transformation which an adhesive agent is going to peel from the metal foil of a base film, even if it exists in a high-temperature, high-humidity environment, between a base film and a metal foil, Generation of delamination can be suppressed.

  Moreover, the adhesive agent which concerns on this invention can be comprised so that polyester polyol and aromatic polyisocyanate may be included. According to this structure, generation | occurrence | production of the delamination between the base film and metal foil in a high temperature, high humidity environment can be suppressed reliably.

  According to the adhesive according to the present invention, it is possible to suppress the occurrence of delamination between the base film and the metal foil even in a high-temperature and high-humidity environment in the drawn battery outer packaging material. .

  Moreover, the lithium ion battery which has the battery outer packaging material which adhere | attached the base film and metal foil using the adhesive which concerns on this invention, and the battery outer packaging material to which the drawing process was given can be provided.

It is sectional drawing of the battery outer packaging material to which the adhesive agent which concerns on one Embodiment of this invention is applied. It is a graph which shows the relationship between the temperature by the penetration measurement of a thermomechanical analysis, and a displacement rate about an adhesive agent. FIG. 2 is a perspective view of the battery outer packaging material shown in FIG. It is a graph which shows the relationship between the compounding ratio of a hardening | curing agent and the displacement rate in 80 degreeC by the penetration measurement of TMA about an adhesive agent.

  Hereinafter, a battery packaging material to which an adhesive according to an embodiment of the present invention is applied will be described with reference to the drawings. FIG. 1 is a cross-sectional view of the battery outer packaging material 10. As shown in FIG. 1, it is composed of a base material layer 11, an adhesive layer 12, a metal foil layer 13, an adhesive layer 14, and a sealant layer 15 from the outside to the inside (as used in a lithium ion battery). The The thickness of the battery outer packaging material 10 is set to, for example, 50 μm to 300 μm from the viewpoint of battery capacity and moldability.

  The base material layer 11 is formed of a base material film that protects the metal foil layer 13 and improves puncture resistance, and for example, a stretched polyester film or a stretched nylon film is used. Examples of the polyester film include films made of polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polycarbonate, and the like. Moreover, as a polyamide film, the film which consists of nylon 6, nylon 6,6, nylon 6,10 etc. is mentioned, for example. These resins may contain additives such as flame retardants, lubricants, antiblocking agents, antioxidants, light stabilizers, and tackifiers. Moreover, the base material layer 11 may be a single layer, and the film described above may be a known layer or a multilayer laminated with the adhesive of the present invention. The thickness of the base film layer is set to, for example, 5 μm to 50 μm from the viewpoint of mechanical strength and moldability.

  The adhesive layer 12 is used to bond the base material layer 11 and the metal foil layer 13, and an adhesive having a displacement rate of less than 3% at 80 ° C. by penetration measurement of thermomechanical analysis (TMA) is preferably used. Is less than 2.5%, more preferably less than 2.0%, and particularly preferably less than 1.5%. The adhesive is formed from a two-component curable adhesive composed of a main agent such as polyester, polyether, or polyurethane. Preferably, a two-component curable polyurethane adhesive using a polyol such as polyester polyol, polyether polyol or acrylic polyol as a main ingredient and aromatic or aliphatic isocyanate as a curing agent is used, more preferably polyester polyol. Is used as a main agent and aromatic polyisocyanate as a curing agent. The thickness of the adhesive layer 12 is set to, for example, 1 μm to 10 μm from the viewpoints of adhesiveness and moldability.

  The metal foil layer 13 prevents water vapor from entering from the outside, and is formed of a metal foil such as aluminum, nickel, and stainless steel. Aluminum foil is preferable from the viewpoint of economy. As the aluminum foil, the ductility is improved by containing iron, and the occurrence of pinholes due to bending is reduced, so that iron is 0.3 to 9.0% by weight, preferably 0.7 to 2.0. Those containing wt% are used. Furthermore, from the viewpoint of spreadability, a soft aluminum foil that has been subjected to an annealing treatment is preferably used. The thickness of the metal foil layer 13 is set to, for example, 5 μm to 100 μm from the viewpoint of moisture barrier properties and moldability.

  In addition, the metal foil layer 13 prevents the dissolution or corrosion of the surface of the metal foil due to an acidic substance or the like, and improves the adhesion with the base film or the adhesive resin film. An acid-resistant treatment may be performed on the surface. Examples of the acid resistance treatment method include chromate treatment, boehmite treatment, parkerizing treatment, triazine thiol treatment, and the like.

  The adhesive layer 14 adheres the metal foil layer 13 and the sealant layer 15 and is formed of an adhesive or an adhesive resin. As the adhesive, for example, a two-component curable adhesive composed of a main component such as polyester, polyether, polyurethane, or the like is used. Preferably, a two-component curable polyurethane adhesive using a polyol such as polyester polyol, polyether polyol, acrylic polyol or the like as a main agent and an aromatic or aliphatic isocyanate as a curing agent is used. Examples of the adhesive resin include polyethylene resins such as low density polyethylene, high density polyethylene, and ethylene-α olefin copolymer, polypropylene resins such as polypropylene and propylene / ethylene copolymer, and unsaturated carboxylic acid. Resin modified with acrylic acid, methacrylic acid, maleic anhydride, etc., ion-crosslinked resin, or the like is used. Olefin-based elastomers and / or styrene-based elastomers may be added to these resins. When the adhesive layer 14 is formed of an adhesive resin, it may be a single layer or a multilayer in which these resins are laminated. The thickness of the adhesive layer 14 is set to, for example, 1 μm to 50 μm from the viewpoint of adhesiveness and moldability.

  The sealant layer 15 is for heat-sealing the sealant layers 15 at the time of manufacturing a lithium ion battery and sealing them. For example, a polyethylene resin such as low-density polyethylene, high-density polyethylene, or ethylene-α-olefin copolymer. And polypropylene resins such as polypropylene and propylene / ethylene copolymers, resins obtained by modifying these resins with unsaturated carboxylic acid, acrylic acid, methacrylic acid, maleic anhydride, and the like, and ion-crosslinked resins. Olefin-based elastomers and / or styrene-based elastomers may be added to these resins. Further, the sealant layer 15 may be a single layer or a multilayer in which these resins are laminated. The thickness of the sealant layer 15 is set to 20 μm to 200 μm, for example, from the viewpoint of sealing properties and moldability.

  Next, the manufacturing method of the battery outer packaging material 10 using the adhesive which concerns on one Embodiment of this invention is demonstrated. First, an adhesive is prepared in which the displacement rate at 80 ° C. measured by TMA penetration is less than 3%. And this adhesive agent is apply | coated to one surface of metal foil, the one surface of a base film is bonded together and this is adhere | attached, and the laminated body of the base material layer 11, the adhesive bond layer 12, and the metal foil layer 13 Get. Regarding the lamination of the metal foil layer 13, the adhesive layer 14, and the sealant layer 15, a known method may be used, and may be performed in any case before and after the base film and the metal foil are bonded.

  Below, the battery outer packaging material 10 to which the adhesive according to the present invention is applied will be described in detail by way of examples. However, the present invention is not limited to these examples.

Example 1
The adhesive is a two-component curing type polyurethane adhesive in which the main agent is a polyester polyol and the curing agent is an aromatic polyisocyanate, and the blending ratio of the curing agent is 17% with respect to the total weight of the main agent and the curing agent (that is, The main agent: curing agent = 83: 17) was prepared. This adhesive forms a thin film having a thickness of 228Myuemu, penetration measurement of thermomechanical analyzer (SII manufactured TM120A) _{(N 2} atmosphere, probe diameter 1 mm in diameter, load 2g, heating rate 5 ° C. / min), the The displacement amount (penetration amount) from 25 ° C. to 100 ° C. was measured. Here, the relationship between the temperature and the displacement rate is shown in FIG. 2 as a displacement rate obtained by dividing the displacement amount by the thickness of the thin film (here, 228 μm). As shown in FIG. 2, the displacement rate at 80 ° C. of this adhesive was about 1.45%.

  This adhesive, a stretched nylon film having a thickness of 25 μm as a base film, and an aluminum foil having a thickness of 40 μm as a metal foil were prepared. Further, acid-modified polypropylene was prepared as the adhesive layer 14 and polypropylene was prepared as the sealant layer 15 so that the total thickness of the adhesive layer 14 and the sealant layer 15 was 45 μm. Using these, the battery outer packaging material 10 was prepared so that the thickness of the adhesive layer 12 was 3 μm.

(Comparative Example 1)
As the adhesive, a two-component curable polyurethane adhesive in which the main agent is polyester polyol and the curing agent is aromatic polyisocyanate, and the blending ratio of the curing agent is 9.5% was prepared. When a thin film having a thickness of 275 μm was formed for this adhesive and TMA penetration measurement was performed under the same conditions as in Example 1, the displacement rate at 80 ° C. was about 3.17% as shown in FIG. It became. And the battery outer packaging material was created by the same structure as Example 1 except using this adhesive agent.

(Example 2)
The same adhesive as in Example 1 was prepared. Then, a 12 μm stretched polyethylene terephthalate film and a 15 μm stretched nylon film were laminated as the base film (stretched polyethylene terephthalate is the outermost layer), and a 40 μm aluminum foil was prepared as the metal foil. Further, acid-modified polypropylene was prepared as the adhesive layer 14 and polypropylene was prepared as the sealant layer 15 so that the total thickness of the adhesive layer 14 and the sealant layer 15 was 80 μm. Using these, the battery outer packaging material 10 was prepared so that the thickness of the adhesive layer 12 was 3 μm.

(Comparative Example 2)
The same adhesive as in Comparative Example 1 was prepared. And the battery outer packaging material was created by the same structure as Example 2 except using this adhesive agent.

(Peeling evaluation)
As shown in FIG. 3, these battery outer packaging materials 10 were subjected to deep drawing processing of 100 mm wide by 100 mm deep and 9.5 mm deep by using a drawing machine on the battery outer packaging material 10 of 200 mm wide by 200 mm wide. did. This is stored in a temperature-controlled room under an environment of temperature 80 ° C. and humidity 90%, and delamination occurs between the base material layer 11 and the metal foil layer 13 in the upper bent portion L formed in the battery outer packaging material 10. It was confirmed visually. This is summarized in Tables 1 and 2.

  As shown in Table 1, in the case where the base material layer 11 is a single layer of a stretched nylon film, in Comparative Example 1 in which the displacement rate of the adhesive is 3% or more, delamination occurred after 2 weeks, In Example 1 in which the displacement rate was less than 3%, delamination did not occur even after 4 weeks after being too large for 2 weeks. Further, as shown in Table 2, even in the case where the base material layer 11 was a multilayer of a stretched polyethylene terephthalate film and a stretched nylon film, delamination occurred after 2 weeks in Comparative Example 2 where the displacement rate was 3% or more. On the other hand, in Example 2 where the displacement rate was less than 3%, delamination did not occur after 2 weeks. From these results, by setting the displacement rate at 80 ° C. by the TMA penetration measurement to less than 3% for the adhesive, even under high temperature and high humidity environment, it is between the base film and the metal foil. Generation of delamination can be suppressed.

(Reference example)
As the adhesive, a two-component curing type polyurethane adhesive in which the main agent is polyester polyol and the curing agent is aromatic polyisocyanate, and the blending ratio of the curing agent is 24% was prepared. About this adhesive, when a thin film having a thickness of 270 μm was formed and TMA penetration measurement was performed under the same conditions as in Example 1, the displacement rate at 80 ° C. was about 3.82% as shown in FIG. became. Therefore, the relationship between the blending ratio of the curing agent and the displacement rate at 80 ° C. by TMA penetration measurement is shown in FIG. As shown in FIG. 4, the relationship between the blending ratio of the curing agent and the displacement rate at 80 ° C. by TMA penetration measurement became convex downward. From this, it is possible to determine the range of the blending ratio of the curing agent necessary for setting the displacement rate at 80 ° C. by TMA penetration measurement to less than 3, for example, from the approximate curve of FIG.

10 Battery outer packaging material 11 Base material layer (base material film)
12 Adhesive layer (adhesive)
13 Metal foil layer (metal foil)
14 Adhesive layer 15 Sealant layer L Upper bent part

Claims (4)

It is used for a battery outer packaging material comprising a base film and a metal foil, and is an adhesive that bonds the base film and the metal foil,
An adhesive having a displacement rate of less than 3% at 80 ° C. by penetration measurement in thermomechanical analysis. Polyester polyol,
The adhesive according to claim 1, comprising an aromatic polyisocyanate.   A battery outer packaging material comprising a base film, a metal foil, and the adhesive according to claim 1.   The lithium ion battery which has a battery outer packaging material of Claim 3 to which the drawing process was given.

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