US Patent 8109316 Slat member and fireproof, heat-insulating slat and rolling door

A fireproof, heat-insulating slat consists of a pair of slat members having the same structure and disposed in the opposite directions. An enclosed space is formed between the pair of slat members. A first upper shoulder and a first lower shoulder are formed on the top end of the slat from the left to the right, and a second lower shoulder and a second upper shoulder are formed on the bottom end of the slat from the left to the right. An upper hinge and a lower hinge part are formed on the first lower shoulder and the second lower shoulder, respectively, and the upper hinge part and the lower hinge part are bent toward the first upper shoulder and the second upper shoulder, respectively. The enclosed space is filled with a fireproof, heat-insulating material.