Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1998-10-26
2001-01-23
Yao, Sam Chaun (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S176000, C156S219000, C156S220000, C264S284000, C264S293000
Reexamination Certificate
active
06176954
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a liquid-permeable topsheet for a body exudates absorbent article such as a sanitary napkin or a disposable diaper, an apparatus and a method for manufacturing the topsheet.
Japanese Laid-Open Patent Application No. Sho57-82505 discloses a disposable diaper having a topsheet composed of a hydrophobic net-like sheet of thermoplastic synthetic resin and a hydrophilic sheet such as a nonwoven fibrous sheet. The hydrophobic net-like sheet is placed on the hydrophilic sheet and these sheets are integrally bonded together by subjecting them to a heat-embossing treatment.
Japanese Laid-Open Patent Application No. Hei7-328061 discloses a body exudates absorbent article such as a sanitary napkin having a topsheet composed of a liquid-permeable nonwoven fibrous sheet and a plurality of parallel lines of film strips of thermoplastic synthetic resin. The film strips are placed on an upper surface of the liquid-permeable nonwoven fibrous sheet and these are integrally heat-sealed under pressure so that regions of the nonwoven fibrous sheet exposed between each pair of adjacent film strips may retain liquid-permeability.
In these known topsheets, the net-like sheet and the film strips certainly serve to improve a strength of the topsheet, to control a direction in which body exudates flow within the topsheet and to conceal menstrual discharge absorbed in an absorbent core of an article such as a diaper or a sanitary napkin.
However, in these known topsheets obtained by welding the net-like sheet or the film strips onto the nonwoven fibrous sheet, welded areas tend to have a higher rigidity than that at non-welded areas and thereby tend to deteriorate softness of the topsheet as a whole. In consequence, these topsheets are necessarily poor fitting, uncomfortable to wear and cause leakage of body exudates from the article.
SUMMARY OF THE INVENTION
In view of the foregoing problems, it is a principal object of the invention to allow a plurality of filaments of thermoplastic synthetic resin to be continuously bonded to an upper surface of a nonwoven fibrous sheet of thermoplastic synthetic resin in order to obtain a liquid-permeable topsheet without deteriorating a softness of the topsheet due to such bonding or, if any, with such deterioration acceptably alleviated.
A liquid-permeable topsheet for a body exudates absorbent article, according to the invention comprises:
a liquid-permeable nonwoven fibrous sheet of thermoplastic synthetic resin and a plurality of filaments of thermoplastic synthetic resin;
the filaments extending in one direction parallel to one another and continuously bonded to an upper surface of the nonwoven fibrous sheet longitudinally thereof, and
a composite sheet of these nonwoven fibrous sheet and filaments describing undulations having crests and troughs both extending transversely of the filaments and alternately repeating longitudinally of the filaments at a predetermined pitch.
An apparatus for manufacturing a liquid-permeable topsheet for body exudates absorbent article according to the invention comprises:
a pair of mutually engageable embossing means for an embossing treatment of a continuous composite sheet web composed of a liquid-permeable nonwoven fibrous sheet of thermoplastic synthetic resin and a plurality of filaments of thermoplastic synthetic resin extending in one direction parallel to one another and continuously bonded to an upper surface of the nonwoven fibrous sheet longitudinally thereof;
the embossing means including a first roll and a second roll;
the first roll being provided on a circumferential surface thereof with cones arranged in a plurality of lines extending in an axial direction thereof as well as in a circumferential direction thereof;
the second roll being provided on a circumferential surface thereof with crests of an inverted V-shaped cross-section and troughs of a V-shaped cross-section arranged in a plurality of lines in an axial direction thereof so that the crests and troughs are alternatively arranged in a circumferential direction thereof; and
wherein a line of the cones of the first roll arranged in the axial direction thereof is received by the corrresponding trough of the second roll while the crest of the second roll is received between two lines of cones which are adjacent to each other in the circumferential direction thereof.
A method for manufacturing a liquid-permeable topsheet for body exudates absorbent article according to the invention comprises the steps of:
composing a continuous composite sheet web by integrally bonding a plurality of filaments of thermoplastic synthetic resin onto a surface of a nonwoven fibrous sheet of thermoplastic synthetic resin so that the filaments is spaced apart from and in parallel to one another along a longitudinal direction thereof; and
feeding the composite sheet web into a space between a pair of mutually engageable embossing means for an embossing treatment, while the filaments remain in a thermally softened state.
In the topsheet according to the invention, both the upper surface of the nonwoven fibrous sheet and the filaments continuously bonded thereto present the crests and the troughs alternately appearing longitudinally of the filaments and respectively extending transversely of the filaments. Such topsheet can be easily curved longitudinally of the filaments and relatively soft, since the crests and the troughs form a bellows-like structure. Body exudates absorbent article using this topsheet is easily curved in conformity with a contour of the wearer's body to achieve a good fitness to the wearer's skin.
According to the embodiment in which the fiber density of the nonwoven fibrous sheet progressively increases from the crest to the trough, body exudates can easily spread from the crest toward the trough. In view of a fact that the trough tends to be spaced from the wearer's skin, body exudates discharged on the topsheet rapidly go away from the wearer's skin into the core. Accordingly, an undesirable feeling of wetness during use of the body exudates absorbent article is effectively alleviated by use of such topsheet for such article.
According to the embodiment in which the topsheet includes an opening of relatively large dimension in the bottom of each trough, fibers around such opening extend downward in contact with the core and promote body exudates collected in each trough to move into the core. With a consequence, an undesirable feeling of wetness experienced by the wearer of the body exudates absorbent article is further alleviated by use of such topsheet for the article. Particularly when a fiber density is adjusted to be relatively high around the opening, the feeling of wetness is more significantly alleviated.
When the lower side of the topsheet has convexities, the bottom of each trough is well kept in close contact with the liquid-absorbent core and promotes body exudates collected in this trough to move into the core.
Other and further objects, features and advantages of the invention will appear more fully from the following discription.
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Goda Hiroki
Takai Hisashi
Tsuji Tomoko
Lowe Hauptman & Gilman & Berner LLP
Uni-Charm Corporation
Yao Sam Chaun
LandOfFree
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