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US-12617987-B2 - Adhesive for electrical storage device packaging material, electrical storage device packaging material, electrical storage device container, and electrical storage device

US12617987B2US 12617987 B2US12617987 B2US 12617987B2US-12617987-B2

Abstract

An adhesive for an electrical storage device packaging material containing a polyol compound (A), a polyisocyanate compound (B), and an epoxy resin (C), in which the polyol compound (A) contains an ester bond-containing polyol, and the following formula is satisfied when a stress at the time when a cured film obtained by performing curing under the condition of 80° C. for 2 weeks is stretched to twice its length at a speed of 6 mm/min under an environment of 20° C. and 65% RH is S1 [N/mm 2 ], and a stress at the time when the cured film is held for 100 seconds in a stretched state is S2 [N/mm 2 ]. Formula: 10.0≤(S1−S2)/S1×100≤40.0.

Inventors

  • Koki SHIRAISHI
  • Hiroshi HANAKI
  • Tsutomu Hiroshima
  • Takafumi AKIYAMA

Assignees

  • ARTIENCE CO., LTD.
  • TOYO-MORTON, LTD.
  • TOYOCHEM CO., LTD.

Dates

Publication Date
20260505
Application Date
20230329
Priority Date
20220330

Claims (10)

  1. 1 . An adhesive for an electrical storage device packaging material containing a polyol compound (A), a polyisocyanate compound (B), and an epoxy resin (C), wherein the polyol compound (A) contains an ester bond-containing polyol, wherein the ester bond-containing polyol has an ester bond concentration of 8.5 to 10.5 [mmol/g], and has a weight average molecular weight of 55,000 to 85,000, and the following formula is satisfied when a stress at the time when a cured film obtained by curing the adhesive for an electrical storage device packaging material under the condition of 80° C. for 2 weeks is stretched in a stretched state to twice its length at a speed of 6 mm/min under an environment of 20° C. and 65% RH is S1 [N/mm 2 ], and a stress at the time when the cured film is held for 100 seconds in the stretched state is S2 [N/mm 2 ] 10.0≤( S 1 −S 2)/ S 1×100≤40.0. Formula:
  2. 2 . The adhesive for an electrical storage device packaging material according to claim 1 , wherein the epoxy resin (C) has an epoxy equivalent weight of 90 to 1,200 [g/eq].
  3. 3 . The adhesive for an electrical storage device packaging material according to claim 1 , wherein the ester bond-containing polyol of the polyol compound (A) is a polyester polyol, and the epoxy resin (C) contains an epoxy resin having an epoxy equivalent weight of 150 to 1,000 [g/eq].
  4. 4 . The adhesive for an electrical storage device packaging material according to claim 1 , wherein the ester bond-containing polyol of the polyol compound (A) is a polyester urethane polyol, and the epoxy resin (C) contains an epoxy resin having an epoxy equivalent weight of 100 to 450 [g/eq].
  5. 5 . The adhesive for an electrical storage device packaging material according to claim 1 , wherein a storage elastic modulus of the cured film at 120° C. is 1.00×10 5 to 9.99×10 7 [Pa].
  6. 6 . The adhesive for an electrical storage device packaging material according to claim 3 , wherein a storage elastic modulus of the cured film at 120° C. is 1.00×10 5 to 9.99×10 7 [Pa].
  7. 7 . The adhesive for an electrical storage device packaging material according to claim 4 , wherein a storage elastic modulus of the cured film at 120° C. is 1.00×10 5 to 9.99×10 7 [Pa].
  8. 8 . An electrical storage device packaging material having a configuration in which at least an outer layer side resin film layer, an outer layer side adhesive layer, a metal foil layer, an inner layer side adhesive layer, and a heat seal layer are sequentially laminated, wherein the outer layer side adhesive layer is a cured product of the adhesive for an electrical storage device packaging material according to claim 1 .
  9. 9 . An electrical storage device container formed from the electrical storage device packaging material according to claim 8 , wherein the outer layer side resin film layer forms a convex surface and the heat seal layer forms a concave surface.
  10. 10 . An electrical storage device comprising: the electrical storage device container according to claim 9 .

Description

CROSS-REFERENCE TO RELATED APPLICATION This application claims priority under 35 U.S.C § 119 to Japanese Patent Application No. 2022-055830, filed on Mar. 30, 2022, and Japanese Patent Application No. 2022-177759, filed on Nov. 7, 2022. Each of the above application(s) is hereby expressly incorporated by reference, in its entirety, into the present application. BACKGROUND Technical Field The disclosure relates to an electrical storage device packaging material for forming an electrical storage device container of a lithium-ion battery or the like, and to an adhesive for an electrical storage device packaging material, which has a good appearance and has excellent adhesive strength, moldability, and durability of a molded product in a high temperature atmosphere, an electrical storage device packaging material using the adhesive, an electrical storage device container, and an electrical storage device. Description of Related Art The rapid growth of electronic equipment such as mobile phones and portable personal computers has increased the demand for electrical storage devices such as secondary batteries (for example, lithium-ion batteries and nickel-hydrogen batteries), and electrochemical capacitors (for example, electric double layer capacitors). Among these, small lithium-ion batteries are attracting attention because of their high energy density and light weight. Conventionally, metal cans are being used as exterior bodies for lithium-ion batteries, but from the viewpoint of weight reduction and productivity, packaging materials in which plastic films, metal foils, or the like are laminated are becoming mainstream. For example, Patent Document 1 discloses that an electrical storage device packaging material, in which a polyurethane adhesive containing a polyester urethane polyol having a predetermined urethane bond concentration and a polyisocyanate is used for an outer layer side adhesive layer, has excellent moldability and can suppress appearance defects such as floating between layers without a decrease in adhesive strength between layers even after high-temperature, high-humidity, long-term durability tests. Patent Document 2 discloses that a laminate adhesive containing a polyester urethane polyol having a predetermined number average molecular weight and a polyisocyanate, and having a sum of the urethane bond content and the isocyanate group content within a predetermined range improves processability, moldability, moisture and heat resistance, and appearance. Patent Document 3 discloses a laminate adhesive containing a polyester urethane polyol having a weight average molecular weight of approximately 40,000, a polyisocyanate, and an epoxy resin having a specific epoxy equivalent weight, in a predetermined range or amount, and describes that the laminate adhesive can be used as an exterior material or the like for a secondary battery such as a lithium-ion battery. PATENT DOCUMENTS [Patent Document 1] Japanese Patent Laid-Open No. 2021-99915[Patent Document 2] Japanese Patent Laid-Open No. 2016-196580[Patent Document 3] Japanese Patent Laid-Open No. 2019-156925 SUMMARY In recent years, with the expansion of applications such as in-vehicle use and household power storage, it has become necessary for secondary batteries to have a large capacity, and for electrical storage device packaging materials to have good moldability. In addition, for automotive applications, good long-term outdoor durability is required in terms of heat resistance and moisture and heat resistance, and from the viewpoint of safety, the development of polymer type lithium-ion batteries and all-solid-state batteries from which low-boiling carbonate solvents contained in the electrolytic solution are removed is progressing, and accordingly, the required heat resistance endurance temperature is also increasing. However, the packaging materials described in Patent Documents 1 and 2 mainly contain a polyester polyurethane resin in the adhesive layer, and do not contain an epoxy resin. Therefore, there is a problem that the molecular weight decreases due to hydrolysis of the polyester skeleton, and delamination occurs in the molded product when the packaging material is continuously exposed to a severe external environment. A laminate adhesive described in Patent Document 3 does not satisfy the characteristic formula of the application because the laminate adhesive has a low weight average molecular weight of a polyol component and is extremely soft. Therefore, there is a problem that the adhesive strength is inferior in a high temperature atmosphere of approximately 120° C., for example. Accordingly, the disclosure provides an adhesive for an electrical storage device which is excellent in adhesive strength in a high temperature atmosphere (hereinafter referred to as hot strength), particularly in hot strength between a film and a metal foil. In addition, the disclosure provides an electrical storage device packaging material, an e