| 摘要 |
PROBLEM TO BE SOLVED: To provide a knapsack serving as a floater-like life preserver and weighing less than a conventional knapsack by forming a knapsack constituting wall of an elastic member having numerous foam parts so that the knapsack is afloat in water. SOLUTION: The cross section structure of a back wall 3 for the main body 1 of this knapsack is composed of a synthetic resin base 10 piled on the outer lateral face of an inner leather 9, sheet-like air bags 11 piled in triple over the outer side of the base 10, and an outer leather 12 piled on the outer side of the air bag 11. The air bag 11 is of such a type that it is generally used as a shock absorber, and so many pieces of a circular part consisting of front and rear films 11a, 11b of a thin synthetic resin film not mutually stuck together, are arranged independently of each other, and the front and the rear film 11a, 11b of the part other than the circular part are mutually stuck to each other, with the circular part consisting of the not mutually stuck films 11a, 11b containing an air sealed in a closed cell state, to form a foam part 11c. |
