Abstract: A safety valve having a thickness partially reduced in a battery case includes a flat part, and a groove formed around the flat part and being concave toward an inside of the battery case. When an internal pressure of the battery case is equal to or higher than a predetermined explosion-proof pressure, a concave shape of the groove is reversed to protrude outward from the battery case, so that the groove is cracked and therefore opened.

Abstract: Provided is a manufacturing method for a rectangular can according to which it is possible to bring an angle formed by a step surface of a step provided in a rectangular can body and an inner wall surface of the rectangular can body closer to 90 degrees. In a step-forming step, using a die 310 that is provided on an outer wall surface side of a sidewall on which the step is to be formed, a mandrel 410 for sandwiching the sidewall between the mandrel 410 and the die 310 on the bottom side relative to a portion where the step is to be formed in the inner wall surface on which the step is to be formed, and a punch 420 for pressing the side opposite to the bottom side relative to the portion where the step is to be formed in the inner wall surface on which the step is to be formed and compressing the sidewall between the punch 420 and the die 310, the step is formed by performing multiple instances of a pressing operation performed by the punch 420.

Abstract: An easily unsealable container closure having re-sealing performance and comprising a closure member having an opening portion that has been formed in advance, and an unsealing tab which is so fitted to the outer surface side of the closure member as to cover the opening portion and is hermetically adhered to the periphery of the opening portion, wherein the unsealing tab includes a flexible tab member and a plug member integrally adhered to the tab member and is so formed as to be fitted to the opening portion of the closure member, and the flexible tab member is hermetically fixed to the periphery of the opening portion in the closure member so as to be torn off. The container closure offers re-sealing performance which can be repetitively effected to temporarily seal again the once unsealed opening, and further offers excellent re-sealing performance, unseal indication function and easy-to-unseal performance.