Sanitary napkin

• US 7,959,622 B2
• Filed: 01/31/2006
• Issued: 06/14/2011
• Est. Priority Date: 02/23/2005
• Status: Active Grant

• Current Assignee: Unicharm Corporation
• Original Assignee: Unicharm Corporation
• Inventors: Kudo, Jun, Miyama, Takuya
• Primary Examiner(s): Stephens; Jacqueline F
• Application Number:
  US11/344,915
• Publication Number:
  US 20060189954A1
• Time in Patent Office: 1,960 Days
• Field of Search: 604/385.01, 604/385.201, 604/385.19, 604/380
• US Class Current: 604/385.201
• CPC Class Codes: A61F 13/15203 Properties of the article, e.g. stiffness or absorbency chemical aspects A61L15/00
• CPC Class Codes: A61F 13/4704 having preferential bending zones, e.g. fold lines or grooves
• CPC Class Codes: A61F 13/47218 with a raised crotch region, e.g. hump
• CPC Class Codes: A61F 13/533 having discontinuous areas of compression
• CPC Class Codes: A61F 13/536 having discontinuous areas of compression
• CPC Class Codes: A61F 2013/15357 Stiffness, e.g. Taber rigidity

Abstract

A sanitary napkin includes a liquid-permeable topsheet, a backsheet, and a liquid-absorbent layer disposed between the topsheet and the backsheet. The liquid-absorbent layer has a vagina-facing region on a longitudinal centerline of the sanitary napkin and side regions on both sides of the vagina-facing region. The liquid-absorbent layer has a greater thickness and a greater bending stiffness in the vagina-facing region than in the side regions to provide hinge lines along boundaries between the vagina-facing region and the side regions.

Claims

1. A sanitary napkin comprising

a liquid-permeable topsheet,

a backsheet, and

a liquid-absorbent layer disposed between the topsheet and the backsheet,

wherein the liquid-absorbent layer has a vagina-facing region on a longitudinal centerline of the sanitary napkin configured to face only a wearer'"'"'s vaginal opening and side regions on both sides of the vagina-facing region configured to face only areas of a wearer'"'"'s crotch other than the wearer'"'"'s vaginal opening,

wherein the liquid-absorbent layer comprises a lower absorbent core and an upper absorbent core disposed on a body surface of the lower absorbent core, wherein the upper absorbent core has a smaller area than the lower absorbent core and lies only within the vagina-facing region of the liquid absorbent layer,

wherein said liquid-absorbent layer further comprises two hinge lines, each extending in the longitudinal direction along opposite lateral boundaries between the vagina-facing region and the side regions of the liquid absorbent layer, and

wherein the hinge lines each comprises a plurality of linear cuts extending, along a maximum dimension of the linear cuts, in intervals along a single line in the longitudinal direction of the sanitary napkin and penetrating at least a portion of a thickness of the lower absorbent core, there being no linear cuts in the vagina-facing region,

said sanitary napkin further comprising outer compression lines, wherein the liquid absorbent layer is compressed together with the topsheet, on both sides of the longitudinal centerline and extend longitudinally of the sanitary napkin, wherein the outer compression lines are laterally located entirely outside of the hinge lines.

2. The sanitary napkin of claim 1, wherein the vagina-facing region has a plurality of high-density portions where the lower absorbent core is locally compressed.

3. The sanitary napkin of claim 2, wherein the upper absorbent core is secured on the lower absorbent core by providing laterally opposing side portions of the upper absorbent core with compression portions where the upper and lower absorbent cores are compressed together.

4. The sanitary napkin of claim 2, wherein the lower absorbent core has a greater basis weight and a greater density in the vagina-facing region than in the side regions.

5. The sanitary napkin of claim 2, wherein the liquid-absorbent layer has a front region in front of the vagina-facing region and the side regions and a rear region behind the vagina-facing region and the side regions, and the lower absorbent core has a greater bending stiffness in the front and rear regions than in the side regions.

6. The sanitary napkin of claim 1, wherein compression portions where the liquid-absorbent layer is compressed and recessed together with the topsheet lie on both sides of the longitudinal centerline and extend longitudinally of the sanitary napkin, and the hinge lines are located inside the compression portions.

7. The sanitary napkin of claim 1, wherein compression portions where the liquid-absorbent layer is compressed and recessed together with the topsheet lie on both sides of the longitudinal centerline and extend longitudinally of the sanitary napkin, and the hinge lines are located outside the compression portions.

8. The sanitary napkin of claim 1, wherein a difference in Gurley stiffness between the vagina-facing region and the side regions is at least 1.96 mN.

9. The sanitary napkin of claim 1, wherein the hinge lines lie on both sides of the longitudinal centerline and extend in parallel to the longitudinal centerline.

10. The sanitary napkin of claim 1, wherein the hinge lines lie on both sides of the longitudinal centerline and extend arcuately to have an intermediate portion closer to the longitudinal centerline, the intermediate portion extending along the single line in the longitudinal direction of the sanitary napkin.

11. The sanitary napkin of claim 1, wherein the absorbent core is an absorbent sheet whose hydrophilic fibers are bonded together through a binder.

12. The sanitary napkin of claim 11, wherein the absorbent sheet is further heated and pressed.

13. The sanitary napkin of claim 1, wherein the cuts penetrate into low-density portions of the lower absorbent core where a density of the lower absorbent core is locally decreased.

14. The sanitary napkin of claim 1, wherein a cushion layer having a lower density than the absorbent core is disposed between the liquid-absorbent layer and the topsheet.

15. The sanitary napkin of claim 1, wherein each of the pair of hinge lines is co-extensive in the longitudinal direction with the upper absorbent core.