US-12617977-B2 - Pressure sensitive adhesive sheet for batteries and lithium-ion battery

Abstract

A pressure sensitive adhesive sheet for batteries that includes a base material and a pressure sensitive adhesive layer provided on one surface side of the base material and containing inorganic fine particles. The haze value of the pressure sensitive adhesive layer is 50% or more and 85% or less.

Inventors

• Takeshi ANSAI
• Yuichi KURATA

Assignees

• LINTEC CORPORATION

Dates

Publication Date

20260505

Application Date

20190918

Priority Date

20180919

Claims (7)

1. 1 . A pressure sensitive adhesive sheet for batteries, comprising: a base material layer and a pressure sensitive adhesive layer provided on only one surface side of the base material, the pressure sensitive adhesive layer contains inorganic fine particles, the inorganic fine particles comprise at least one of calcium carbonate and aluminum hydroxide, and are free from alumina, an average particle diameter of the inorganic fine particles is 0.8 μm or more and 10 μm or less, a haze value of the pressure sensitive adhesive layer is 50% or more and 85% or less, and a thickness of the pressure sensitive adhesive layer is 1 μm or more and 10 μm or less.
2. 2 . The pressure sensitive adhesive sheet for batteries as recited in claim 1 , wherein a total luminous transmittance of the pressure sensitive adhesive layer is 80% or more.
3. 3 . The pressure sensitive adhesive sheet for batteries as recited in claim 1 , wherein a content of the inorganic fine particles in the pressure sensitive adhesive layer is 1 vol % or more and 50 vol % or less with respect to the pressure sensitive adhesive layer.
4. 4 . A lithium-ion battery in which two or more conductors are fixed in a state of being in contact with each other inside the battery using a pressure sensitive adhesive sheet, wherein: the pressure sensitive adhesive sheet comprises a base material and a pressure sensitive adhesive layer provided on only one surface side of the base material, the pressure sensitive adhesive layer contains inorganic fine particles, the inorganic fine particles comprise at least one of calcium carbonate and aluminum hydroxide, and are free from alumina, an average particle diameter of the inorganic fine particles is 0.8 μm or more and 10 μm or less, a haze value of the pressure sensitive adhesive layer is 50% or more and 85% or less, and a thickness of the pressure sensitive adhesive layer is 1 μm or more and 10 μm or less.
5. 5 . The lithium-ion battery according to claim 4 , wherein a total luminous transmittance of the pressure sensitive adhesive layer is 80% or more.
6. 6 . The lithium-ion battery according to claim 4 , wherein a content of the inorganic fine particles in the pressure sensitive adhesive layer is 1 vol % or more and 50 vol % or less with respect to the pressure sensitive adhesive layer.
7. 7 . The lithium-ion battery according to claim 4 , wherein the haze value of the pressure sensitive adhesive layer is 73.4% or more and 85% or less.

Description

TECHNICAL FIELD The present invention relates to a pressure sensitive adhesive sheet for batteries and a lithium-ion battery manufactured using the pressure sensitive adhesive sheet for batteries. BACKGROUND ART In some batteries, strip-like laminates are housed inside the batteries in a state of being wound up. Such a laminate is formed by laminating a positive electrode, a negative electrode, and separators located between the positive and negative electrodes. The positive and negative electrodes are connected to respective electrode lead-out tabs of conductors, which electrically connect the positive and negative electrodes respectively to a positive electrode terminal and a negative electrode terminal of the battery. A pressure sensitive adhesive sheet may be used as a stopper for the above wound-up laminate and/or used for fixation of the electrode lead-out tabs to the electrodes. As such a pressure sensitive adhesive sheet, generally, a sheet composed of a base material and a pressure sensitive adhesive layer provided on one surface of the base material is used. From a viewpoint of improving the desired performance such as insulation properties, a modified pressure sensitive adhesive sheet may be used which is configured such that an insulation layer that contains an insulating material is provided on the surface of the above base material opposite to the above pressure sensitive adhesive layer or between the above base material and the above pressure sensitive adhesive layer. However, providing the insulation layer, as described above separately from the pressure sensitive adhesive layer may lead to an increase in the manufacturing cost. In this regard, it is also tried to contain an insulating material or the like in the pressure sensitive adhesive layer thereby to improve the insulation properties of the pressure sensitive adhesive sheer, without providing an additional insulation layer, as described above. For example, Patent Document 1 discloses a pressure sensitive adhesive sheet in which the pressure sensitive adhesive layer contains alumina. Patent Document 2 discloses a pressure sensitive adhesive sheet in which the pressure sensitive adhesive layer contains magnesium hydroxide, alumina, magnesium oxide, aluminum hydroxide, silica, boron nitride, titanium oxide, or magnesium carbonate. PRIOR ART DOCUMENTS Patent Documents [Patent Document 1] WO2017/038010[Patent Document 2] JP2017-152372A SUMMARY OF THE INVENTION Problems to be Solved by the Invention In recent years, as the energy density of batteries such as lithium ion batteries is enhanced, if has become more important than ever to improve the safety of batteries. For example, when foreign materials are mixed inside a battery, an internal short circuit may occur due to the foreign materials, and the battery may generate heat. When manufacturing batteries, therefore, it is important to prevent such foreign materials from being mixed and it is also important to properly find a battery in which foreign materials are mixed and remove the mixed foreign materials or exclude the battery in which foreign materials are mixed. When manufacturing batteries using the conventional pressure sensitive adhesive sheet, however, if was very difficult to find the foreign materials interposed between the pressure sensitive adhesive sheet and an adherend. The present invention has been made in consideration of such actual circumstances and an object of the present invention is to provide a pressure sensitive adhesive sheet for batteries that has high insulation properties and allows the foreign materials mixed in a battery to be readily found. Another object of the present invention is to provide a lithium-ion battery m which the pressure sensitive adhesive sheet for batteries is used. Means for Solving the Problems To achieve the above objects, first, the present invention provides a pressure sensitive adhesive sheet for batteries, comprising: a base material; and a pressure sensitive adhesive layer provided on one surface side of the base material and containing inorganic fine particles, wherein the hate value of the pressure sensitive adhesive layer is 50% or more and 65% or less (Invention 1). In the pressure sensitive adhesive sheet for batteries according to the above invention (Invention 1), the pressure sensitive adhesive layer contains inorganic fine particles and the haze value of the pressure sensitive adhesive layer falls within the above-described range, so that the pressure sensitive adhesive sheet for batteries can achieve high insulation properties and allows the foreign materials interposed between the pressure sensitive adhesive sheet for batteries and an adherend to be readily found through the pressure sensitive adhesive sheet for batteries. Thus, the pressure sensitive adhesive sheet for batteries can be used thereby to manufacture highly safe batteries in which foreign materials are suppressed from being mixed in the batteries. In the ab