Sheet member, high-density region-containing sheet manufacturing method and disposable diaper using sheet member

Abstract

A high-density region-containing sheet has a high-density region and a low-density region, and a sheet member is produced by joining the high-density region of the high-density region-containing sheet to an elastic member. A sheet in a soft state by imparting preheat is pressed between a pair of opposed shaping rolls and having a toothed region and rotatable. Thus, a high-density region-containing sheet where high-density regions and low-density regions are formed is produced. Such two high-density region-containing sheets are joined through an extended elastic member to form a projection/recess pattern. In such a way, a high-density region-containing sheet can be produced. A sheet member in which at least one of two sheets is a high-density region-containing sheet, the high-density regions are joined through an extended elastic member, and a projection/recess pattern can be formed when the elastic member is contracted is produced.

1 . A sheet member, comprising:
 a first sheet;   a second sheet; and   at least one elastic member having a shape selected from a thread shape, a net shape, a strip shape, and a sheet shape, arranged between the first sheet and the second sheet;   wherein   the first sheet comprises:
 a plurality of high-density regions; and 
 a plurality of low-density regions, wherein the high-density regions substantially alternate with the low-density regions in a predetermined direction, 
   the elastic member is arranged in the predetermined direction in which the plurality of high-density regions alternate with the plurality of low-density regions, and   the elastic member in an expanded state is attached to at least a part of each of the plurality of high-density regions.   
     
     
         2 . The sheet member according to  claim 1 , wherein
 at least the first sheet is formed to have concavities and convexities, in the predetermined direction, in the sheet member.   
     
     
         3 . The sheet member according to  claim 1 , wherein
 the density of the high-density region is 0.05 to 0.6 g/cm 3  in order to obtain a first rigidity.   
     
     
         4 . The sheet member according to  claim 1 , wherein the density of the low-density region is 0.01 to 0.05 g/cm 3  in order to obtain a second rigidity. 
     
     
         5 . The sheet member according to  claim 1 , wherein the length of the high-density region is 0.1 to 1.5 mm in the sheet member. 
     
     
         6 . The sheet member according to  claim 1 , wherein the length of the low-density region is 0.5 to 3 mm in the sheet member. 
     
     
         7 . The sheet member according to  claim 1 , wherein the elastic member is coated with an adhesive, and is attached to the first sheet and the second sheet of the sheet member, to join the elastic member and the high-density regions to each other. 
     
     
         8 . (canceled) 
     
     
         9 . A high-density region-containing sheet manufacturing method of making the sheet member of  claim 1 , comprising the step of:
 compressing a sheet with shaping rolls, each having a toothed area, to manufacture a high-density region-containing sheet having a plurality of high-density regions and a plurality of low-density regions formed therein.   
     
     
         10 . The high-density region-containing sheet manufacturing method according to  claim 9 , wherein the high-density region-containing sheet formed to have concavities and convexities in a longitudinal direction, is manufactured. 
     
     
         11 . The high-density region-containing sheet manufacturing method according to  claim 9 , wherein the sheet is compressed between a pair of the shaping rolls that rotate in a direction opposite to each other. 
     
     
         12 . The high-density region-containing sheet manufacturing method according to  claim 9 , wherein the high-density region and the low-density region alternate with each other in the longitudinal direction of the sheet. 
     
     
         13 . The high-density region-containing sheet manufacturing method according to  claim 12 , wherein the shaping rolls has at least one toothed area and at least one grooved area. 
     
     
         14 . The high-density region-containing sheet manufacturing method according to  claim 9 , wherein the grooved area is covered with a thermally insulating material. 
     
     
         15 . A high-density region-containing sheet manufacturing method of making the sheet member of  claim 1 , comprising the step of:
 melting a low-density sheet, filming a part of the low-density sheet, and adding high-density regions to the sheet.   
     
     
         16 . A disposable diaper comprising:
 a chassis composed of a front torso-surrounding portion and a rear torso-surrounding portion, and having a torso-surrounding opening and a pair of right and left leg-surrounding openings positioned in an under-crotch portion;   a liquid-permeable top sheet disposed in at least a part of the chassis;   a liquid-impermeable back sheet disposed on a first side, in the thickness direction, of the liquid-permeable top sheet; and   an absorbent core, having liquid holding properties, disposed between the liquid-permeable top sheet and the liquid-impermeable back sheet,   the sheet member according to  claim 1 , wherein   the sheet member is disposed in an area between the torso-surrounding opening and the leg-surrounding openings of the chassis.   
     
     
         17 . The sheet member according to  claim 1 , wherein the elastic member is free of direct attachment to the low-density regions.