Absorbent article

Details Absorbent article Absorbent article

1995-12-06

1998-04-14

Clarke, Robert A.

Surgery

Means and methods for collecting body fluids or waste material

Absorbent pad for external or internal application and...

604389, A61F 1315

Patent

active

057386692

DESCRIPTION:

BRIEF SUMMARY
This application is a 371 application of PCT/JP/00,622 filed on Mar. 31, 1995.


TECHNICAL FIELD

This invention relates to absorbent articles using a moisture permeable sheet, such as disposable diapers. More particularly, it relates to an absorbent article which undergoes little bleeding of a softening agent used as a component of an adhesive agent and/or a compound with which a crystalline polyolefin is miscible and in which said crystalline polyolefin will dissolve at or above the melting point of said crystalline polyolefin but which will phase separate below the melting point of said crystalline polyolefin. The bleeding of the softening agent and/or the compound causes the adhesive agent coated area of the moisture permeable sheet to be transparent (this phenomenon will hereinafter be referred to as bleed-through).


BACKGROUND ART

Absorbent articles are generally fabricated from a liquid permeable sheet (topsheet), a liquid impermeable sheet (back sheet) and an absorbent member interposed the topsheet and the back sheet, the three elements being adhered together with an adhesive agent at prescribed potions of the three elements.
Among the absorbent articles, disposable diapers use a liquid impermeable sheet endowed with moisture permeability so as to prevent stuffiness and a diaper rash. On the other hand, adhesive agents predominantly used for adhesion of the liquid impermeable back sheet usually contains an increased amount of a softening agent in order to improve initial adhesion and coating properties.
However, when such an adhesive agent is applied to the moisture permeable sheet, the softening agent migrates into the sheet (bleed-through) causing various problems, such as stickiness on the surface of the moisture permeable sheet, adverse influences on performance characteristics of the absorbent articles such as diapers, blocking of the absorbent articles when stacked for storage, and change of adhesion characteristics of the adhesive agent with time due to the change in composition.
Further, the above-mentioned moisture permeable sheet contains a softener for manifestation of moisture permeability and softness. Application of the adhesive agent having an increased amount of the softening agent to such a moisture permeable sheet containing the softener leads to acceleration of the above-mentioned bleed-through.
In order to overcome these problems, Japanese Patent Application Laid-opens 4-77591 and 4-84960 propose adhesive agents applicable to the moisture permeable sheet.
The adhesive agent disclosed in the above-mentioned Japanese Patent Application Laid-open 4-77591 is a hot melt adhesive agent comprising, as main components, an .alpha.-olefin resin and a styrene-ethylene-propylene-styrene block copolymer and further containing a tackifier and a plasticizing oil. According to the above Laid-open application, when the adhesive agent is used for adhering a moisture permeable sheet and nonwoven fabric, no bleed-through of low-molecular weight components occurs, and the tack is lost to show no stickiness on cooling to solidify.
However, the above Laid-open application specifies neither moisture permeability of the moisture permeable sheet nor the bleeding properties on the area to which the adhesive agent has been applied. Another problem associated with this adhesive agent is that in using a moisture permeable sheet comprising a crystalline polyolefin and a softener, the softener contained in the sheet tends to migrate to make the sheet transparent.
The adhesive agent disclosed in the above-mentioned Japanese Patent Application Laid-open 4-84960 comprises a styrene block polymer, a tackifier, and a softening agent, in which the activation energy of the styrene segments and the rubber segments is specified. The above Laid-open application also refers to an absorbent article hardly suffering from bleed-through, which can be obtained by adhering a moisture permeable sheet having a specific moisture permeability with the above adhesive agent.
However, the above Laid-open application provides no sp

REFERENCES:
patent: 4526577 (1985-07-01), Schmidt, Jr. et al.
patent: 4822350 (1989-04-01), Ito et al.
English Abstract of JP 4-77591.
English Abstract of JP 4-84960.

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