| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide an impervious sheet which can prevent a highly water absorptive material from being scattered, positively can refill a fractured portion or a perforated portion thereof when fractured or perforated, and is excellent in workability thereof. SOLUTION: There is provided an impervious sheet comprised of a rear sheet member 2 and a front sheet member. The rear sheet member 2 is provided with a number of depressions 1 each having flexibility and permeability and being filled with a water swelling retaining material 3. The front sheet member is bonded or welded to the rear sheet member 2, has flexibility and impermeability, and blocks the depressions 1 each filled with the water swelling retaining material 3. The rear sheet member 2 is formed of double raschel knit having knitting density of 20 to 60 course/inch and 16 to 40 wale/inch, wherein an inter-depression portion thereof has permeability so that the water swelling retaining material 3 can pass therethrough, and the ratio of an opening area of the depression 1 is 10 to 80%.</p> |
