Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Composite having voids in a component
Reexamination Certificate
2002-03-11
2003-05-20
Lam, Cathy (Department: 1775)
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Composite having voids in a component
C604S380000, C604S382000, C428S308400
Reexamination Certificate
active
06565961
ABSTRACT:
BACKGROUND OF THE INVENTION
I. Field of the Invention
The present invention relates generally to absorbent articles. Particularly, the present invention relates to absorbent articles containing macroporous absorbent materials that provide quick absorption and subsequent containment of liquid. More particularly, the present invention relates to absorbent articles containing aerogels.
II. Description of the Prior Art
It is often desirable to impregnate, cover, or otherwise treat a base material with an absorbent or adsorbent material to form an absorbent article. Examples are found in children's diapers, adult incontinence products, and feminine hygiene products. Other examples include coated paper tissues, toweling, and surgical bandages.
The active adsorbent or absorbent materials used to coat a base material may be fibrous, particulate or both. Fluff pulp is a fibrous absorbent well known in the art. However, fluff pulp fibers have limited absorption capacity and as such, do not always meet the expectations of normal use. In addition, fluff pulp fibers are heavy and bulky, and impart these characteristics into products that contain fluff pulp fibers.
Super adsorbent polymers (hereinafter SAP) in powdered or granular form provide enhanced absorptive capacity over traditional fluff pulp when used alone, or when used in combination with fluff pulp fiber. However, SAP particles that are not well dispersed within an absorbent product undergo a phenomenon known as “gelling” or “gel blocking”.
Contact of SAP with liquid causes SAP to swell. Upon contact with liquid, SAP polymer particles in close proximity coalesce to create an SAP gel of limited permeability. Once formed, the SAP gel prevents utilization of underlying absorbent by blocking access thereto.
The effect of SAP gelling on absorption is of particular concern when the absorbent is used in combination with fluff pulp fibers. This problem is made worse by the well-known and often practiced method of bonding a high percentage of SAP particles directly to the fibers contained in the absorbent article.
In light of the foregoing, there exists a need for improved absorbent articles that are thin, light weight and effective. Still further, there exists a need for adsorbent and absorbent articles free of fluff pulp fibers, having both internal porosity suitable for bulk absorption and subsequent containment of liquid.
SUMMARY OF THE INVENTION
The present invention describes an absorbent article comprising a first substrate and a laminate, wherein the laminate comprises a mixture of binder particles and absorbent macroporous particles.
In addition, the present invention includes the above absorbent article, wherein the binder particles are on average smaller than the absorbent macroporous particles.
Furthermore, the present invention includes the above absorbent article, wherein at least some of the absorbent macroporous particles are coalesced by the binder particles to each other, to the first substrate, or to both each other and to the first substrate.
The present invention also includes the above absorbent article further comprising a second substrate on the laminate, optionally wherein at least some of the absorbent macroporous particles are coalesced or fused by the binder particles to the second substrate, and said laminate is in-between the first substrate and the second substrate.
The present invention also describes an absorbent article, wherein the absorbent macroporous particles are produced by a process comprising the steps of forming a liquid-containing gel, and then removing the liquid from the gel in a way sufficient to produce absorbent macroporous particles.
This invention will be discussed in greater detail in the description that follows. Additional advantages of the invention will become apparent from this discussion, together with accompanying drawings.
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patent: 5750585 (1998-05-01), Park et al.
patent: 5925299 (1999-07-01), Dierckes, Jr. et al.
patent: 5998493 (1999-12-01), Mitchell et al.
patent: 6015608 (2000-01-01), Koslow
patent: 6232520 (2001-05-01), Hird et al.
patent: 6245051 (2001-06-01), Zenker et al.
Koslow Technologies Corporation
Lam Cathy
Ma Shirley
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