High loft low density nonwoven webs of crimped filaments and methods of making same

Abstract

High loft, low density nonwoven webs are produced by forming substantially continuous, spunbond, crimped, bicomponent fibers of A / B side by side morphology in an unheated fiber draw unit. The fibers are then heated and cooled in the absence of impeding forces to achieve maximum crimp in the z-direction and produce a web of lofted material. The resultant material is particularly suitable for use as an insulator. Particulates may be added to the webs if desired.

Description

[0001] This invention relates to a high loft, low density nonwoven material produced from continuous fibers in which the lofty character of the nonwoven material is the result of the fibers comprising the web having a z-direction orientation, resulting from improved processing and the resultant crimping. These materials are particularly suitable for use in a broad range of applications including, without limitation, surge layers for personal care products, acoustic and thermal insulation, packing material, padding, absorbents, filtering, and cleaning materials.DISCUSSION OF THE RELATED ART[0002] In nonwoven webs, the fibers comprising the web are generally oriented in the x-y plane of the web and the resulting nonwoven web material is relatively thin, that is lacking in loft or significant thickness.[0003] Loft or thickness in a nonwoven web suitable for use in personal care absorbent articles promotes comfort (softness) to the user, surge management and fluid distribution to adjace...

AI Technical Summary

Benefits of technology

[0010] The methodology for making high loft, low density nonwoven webs according to the present invention may include initially producing the bicomponent filaments with an unheated fiber draw unit (FDU) rather than using the heated FDUs prevalent in the art. The fibers are then collected on the forming wire and heated to relax the polymer chains and initiate crimping. Immediately after this heating the web is cooled so that the fibers do not bond, thereby maintaining the mobility of the fibers and allowing the fibers to crimp to the desired extent. Other processing parameters such as wire vacuum may be controlled to further allow the fibers to crimp unimpeded. Upon crimping, a high loft, low density fabric is created. Additional heating is then applied to set the web. Processing parameters can be controlled in the final heating phase to maintain the web in the original high loft, low density state or the parameters may be controlled to adjust the density and loft of the web during this phase.

Problems solved by technology

However, in such constructions the fibers of the web still remain in the plane of the web, it is only the plane of the web itself which has been distorted.

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