Stock material or miscellaneous articles – Structurally defined web or sheet – Nonplanar uniform thickness material
Reexamination Certificate
2000-02-24
2003-07-08
Pyon, Harold (Department: 1772)
Stock material or miscellaneous articles
Structurally defined web or sheet
Nonplanar uniform thickness material
C428S131000, C428S137000, C428S138000, C428S141000, C428S158000, C428S166000, C428S304400, C428S315500, C428S913000, C604S358000, C604S370000, C604S379000, C604S383000, C604S385010, C604S385080
Reexamination Certificate
active
06589632
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a liquid-impervious backsheet for a body fluids disposal article such as a disposable diaper or a sanitary napkin.
Japanese Patent Application Disclosure No. 1993-200063 disclose a breathable liquid-impervious backsheet of a disposable diaper having, at least on one surface thereof, rough surface regions comprising a plurality of microprotuberances formed by grains of inorganic filler and relatively smooth surface regions wherein the rough surface regions include breathable micropores each having a diameter of 0.03~5 &mgr;m.
With this known sheet, the rough surface regions are intended to conceal an absorbent core of the article soiled with body fluids and the smooth surface regions having a see through property are intended to tell the article user of a proper timing for exchanging the used article with a fresh one.
The Japanese Patent Application Disclosure No. 1993-200063 discloses such sheet particularly as used as the backsheet of the disposable diaper. The rough surface regions partially underlie the absorbent core and, in such zones, the absorbent core may cover the micropores to make their breathability ineffective. On the other hand, some of the micropores crowded in the rough surface regions may be connected one to another until they form a pore having a sufficiently large diameter to be moisture-pervious and consequently the body fluids may leak therethrough.
SUMMARY OF THE INVENTION
It is an object of this invention to provide an improved liquid-impervious backsheet adapted to maintain a desired breathability and, at the same time, to prevent body fluids from leaking.
According to this invention, there is provided an improvement of liquid-impervious backsheet for a body fluids disposal article having upper and lower surface and made of thermoplastic synthetic resin.
The improvement of this invention is in that the sheet comprises a plurality of independent concave zones depressed downward from the lower surface and a smooth zone extending around said concave zones, each of the concave zones is formed except a peripheral edge thereof with at least one micropore.
According to one embodiment of this invention, at least an upper surface of the sheet is water repellent in the concave zones and at least the upper surface of said sheet is hydrophilic in the smooth zone.
According to another embodiment of this invention, the number of the concave zones per 10 cm
2
of the sheet is in a range of 4~100, a throat-area of each of the concave zones is in a range of 0.002~2.0 cm
2
, an intercentral distance of each pair of adjacent the concave zones is in a range of 0.1~1.5 cm and a height as measured from the lower surface of the sheet to a lower surface of a bottoms in each of the concave zones is in a range of 0.01~0.3 cm.
According to still another embodiment of this invention, a thickness of the sheet is in a range of 10~100 &mgr;m and an inner diameter of each of the micropores is in a range of 0.05~1.0 mm.
REFERENCES:
patent: 3881489 (1975-05-01), Hartwell
patent: 3989867 (1976-11-01), Sisson
patent: 4306559 (1981-12-01), Nishizawa
patent: 4341216 (1982-07-01), Obenour
patent: 4591523 (1986-05-01), Thompson
patent: 4681793 (1987-07-01), Linman et al.
patent: 4824718 (1989-04-01), Hwang
patent: 5158819 (1992-10-01), Goodman, Jr. et al.
patent: 5441691 (1995-08-01), Dobrin et al.
patent: 5567376 (1996-10-01), Turi et al.
patent: 5681301 (1997-10-01), Yang et al.
patent: 5-200063 (1993-08-01), None
patent: 96/00548 (1996-01-01), None
patent: 97/24096 (1997-07-01), None
patent: 98/42289 (1998-10-01), None
Igaue Takamitsu
Imai Shigeo
Sugimura Toru
Lowe Hauptman & Gilman & Berner LLP
Pyon Harold
Simone Catherine A.
Uni-Charm Corporation
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