TABLE OF CONTENTS Air laid webs tend to be bulky structures designed for absorbency The major markets are diaper padding, feminine hygiene pads, incontinence pads, wipes, and other applications where absorbency is a principle property. The absorbency properties are achieved by the use of specially produced high bulk wood pulp fibers known as fluff pulps, and by the use of superabsorbent polymers. Superabsorbent polymers can include superab-sorbent powders such as carboxy methyl cellulose and superabsorbent fibers. Air laid webs can incorporate synthetic fibers for improved strength and resiliency. Bi-compo-nent sheath-core fibers are often used to provide for thermo-bonded structures. The products used for wipes are often latex and/or foam bonded. Spunlace (hydroentangled forms) of the web are becoming popular for the wipes market. Skyt( [74] has identified possibilities for combining the air laid process with other technologies to produce advanced composite structures. This includes multilayer combinations of air laid webs with dry laid (carded), melt-blown, spunbonded, and wet laid webs.
[74]Skyt, A., "Advance Products from Narrow Airlaid Machines", Nonwovens World, June-July 2004, Vol. 13, No. 13.
There are several forms of dry laid carded webs for filter media. Included are needle punch felts, hydroentangled felts, thermal bonded, resin bonded and high loft webs. PGI (Polymer Group, Inc.), Charlotte, North Carolina, USA produces a variety of dry laid webs as indicated in Table 3.1. The table differentiates the various products by bonding technology. It does not...
