| 摘要 |
PURPOSE: To give moisture permeability and water resistance to sheet and improve the strength of the sheet by a method wherein a plurality of ribs are provided in multiple rows at the predetermined intervals respectively in the longitudinal direction and in the lateral direction of the sheet on the surface of the sheet and, recessed parts are provided on the rear surface of the sheet at the positions corresponding to the ribs. CONSTITUTION: Porous sheet 1 consists of ribs 3 and 3' formed on a planar part 2 and recessed parts 4 and 4' provided on the rear surface of the planar part 2 in respectively corresponding to the ribs 3 and 3'. The ribs 3 and 3' are formed respectively in multiple rows in the longitudinal direction or the machine direction or the direction A and in the lateral direction or the cross direction or the direction normal to the direction A. The thickness (b) of the rib 3 in the machine direction is made to be 0.1-4 times as much as the thickness (a) of the planar part 2 and the pitch (c) is preferably set to be 100μ-50mm and the width (d) is preferably set to be 50μ-10mm. Further, the preferable ranges of the thickness (b) of the rib 3', of the pitch (e) and of the width (f) of the rib 3' are made to be equal to those of the ribs arranged in multiple rows in the machine direction. Furthermore, the thicknesses (b) of the ribs 3 and 3' are respectively and preferably to be 3-400μand the thickness (a) of the planar part 2 is preferably 10-200μ. In addition, the depth (g) of the recessed part 4 is made to be 0.1-3 times as much as the thickness (a) of the planar part 2 and its width (h) is made to be 50μ-50mm. |
