Methods of Making Absorbent Members Having Skewed Density Profile

Abstract

Absorbent members and methods of making the same are disclosed. In one embodiment, the absorbent member is a unitary absorbent fibrous web having a density profile through its thickness. In one embodiment, the density profile of the fibrous web is skewed toward one of the surfaces of the fibrous web. In such embodiments, the maximum density of the web may be located outside of the central 30% zone of the thickness of the web. In one embodiment, the method involves subjecting a precursor web to at least one cycle (or pass) through a mechanical deformation process. Typically, the method involves subjecting the precursor web to multiples cycles (or passes) through a mechanical deformation process.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation-in-part of U.S. patent application Ser. No. 13 / 094,310 filed on Apr. 26, 2011.FIELD OF THE INVENTION[0002]The present invention is directed to absorbent members and methods of making the same, and more particularly to absorbent members and methods of making the same that provide the absorbent members with a controlled density profile.BACKGROUND OF THE INVENTION[0003]Currently, some disposable absorbent articles such as diapers, sanitary napkins, and pantiliners are provided with a low density airfelt absorbent core. Airfelt, or comminuted wood pulp, is typically made in a process that involves several steps. The first step is one in which pulp fibers are suspended in water and introduced to a moving screen from the headbox in a wetlaid paper process. The water is removed by a combination of gravity and vacuum before introduction to a drying process to form a relatively high basis weight material that is ...

AI Technical Summary

Benefits of technology

[0013]The methods described herein may be used for a variety of purposes. Such purposes can range from serving as a pre-processing step prior to feeding the precursor material into a hammer mill in order to reduce the energy required to defibrillate the material in the hammer mill, to serving as a unit operation in an absorbent article manufacturing line in order to prepare a completed absorbent member that is ready for use in an absorbent article being made on the line.

Problems solved by technology

Airfelt has several limitations when used as an absorbent core material in disposable absorbent articles.

Airfelt typically has low integrity, and is subject to bunching and roping when wet.

Airfelt typically has a low density and cannot provide as much capillary work potential as a higher density material.

In addition, airfelt has the same density throughout the thickness, and is not readily formed into structures having a density gradient should it be desired to provide a core structure with zones having different properties.

Airlaid structures can be formed in a manner which does provide a density gradient, as in US 2003 / 0204178 A1, but this involves more expensive processes and materials.

The air laying process is often done at an intermediate supplier, resulting in added cost for shipping the material to the converting operation.

The combination of more costly materials, processing and shipping result in a significantly more expensive material and a more complex supply chain.

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