Multilayered elastic sheet structure and process for producing a

Details Multilayered elastic sheet structure and process for producing a Multilayered elastic sheet structure and process for producing a

1995-08-01

1997-11-04

Ryan, Patrick

Stock material or miscellaneous articles

Structurally defined web or sheet

Discontinuous or differential coating, impregnation or bond

428 74, 428 77, 428131, 428152, 428184, 428284, 428286, 428297, 428298, 4283179, 6043852, 156163, 156229, B32B 900

Patent

active

056837879

DESCRIPTION:

BRIEF SUMMARY
The invention relates to a multilayered elastic sheetlike structure as classified in the preamble of claim 1.
Such a multilayered elastic sheetlike structure is already known from U.S. Pat. No. 4,446,189. The known sheetlike structure comprises a layer of an elastic material, for example a polyurethane foam or else a non-cellular material, which is connected to an inelastic fibre or filament layer at mutually spaced-apart connection sites. In the process of production, an originally flat fibre or filament layer is connected to an elastic layer in the untensioned stabs thereof by a needling process, then the compound material is stretched as a whole, and finally unstressed again. In this process, the inelastic fibre or filament layer undergoes a permanent extension and, after untensioning, becomes wavy between the connection sites to the elastic layer, whereas the elastic layer, except for a permanent residual extension, returns substantially back into the original state.
A further multilayered elastic sheetlike element is known from EP Patent 0,217,032. This sheetlike structure differs in the production process from the aforementioned one in that a drawn inelastic fibre or filament layer is used and this layer is connected to an extended elastic layer at spaced-apart connection sites and subsequently the entire sheetlike structure is untensioned. Here too the inelastic fibre or filament layer then becomes wavy between the connection points. The elastic layer is formed of a woven, elastic fibre web.
The known multilayered elastic sheetlike structures have the decisive disadvantage that they are uncheckedly liquid-permeable over their entire area. This is immediately evident in the case of the sheetlike structure of EP Patent 0,217,032, since it after all is based exclusively on fibrous layers.
However, even in the case of the sheetlike structure of U.S. Pat. No. 4,446,189 in the version where the elastic layer consists of a non-cellular material, liquid permeability occurs. It is in this case due to the needling process. Needling sews the fibres or filaments of the inelastic layer to the elastic layer composed of non-cellular material by means of needles. The needles pass through the elastic layer, taking along individual fibres or filaments which, however, as the needles return, remain in the holes formed. The resulting connection of the elastic layer to the non-elastic layer is non-positive. Thus, under mechanical stress, the fibres or filaments can be pulled back out of the holes of the elastic layer, and this effect does indeed occur when the sheetlike structure is extended.
Even if it is assumed that the damage to the elastic layer due to the needling process falls short of leading to a significant increase in the liquid permeability, since, after all, the holes formed in the course of the needling are substantially sealed up again by the fibres punched therethrough, the holes re-open when the sheetlike structure is extended, as a result of the fibres slipping out, and let liquid pass through in an unchecked fashion. In addition, when the sheetlike structure is extended, it is impossible to stretch the fibres to any significant extent, at any rate not into the region of their extension breaking strength. On the contrary, as the force of the extension increases, they slip out of the holes in the elastic layer before that point is reached. This leads only to a minimal increase in the volume occupied by the fibre or filament layer after the extending and subsequent untensioning of the sheetlike structure, as compared with the volume prior to the extending and untensioning.
A further disadvantage of the needling-based technology is that only fibrous layers having relatively short fibres, preferably staple fibres, are suitable for needling, since only short fibres will regularly slide past one another to go from the horizontal assembly into the vertical assembly through the elastic layer. Long fibres in spunbonded webs or melt-blown webs, by contrast, are held by adjacent fibres over a greater length and th

REFERENCES:
patent: 4446189 (1984-05-01), Romanek
patent: 4720415 (1988-01-01), Vander Wielen et al.
patent: 4741944 (1988-05-01), Jackson et al.
patent: 4863779 (1989-09-01), Daponte
patent: 4891258 (1990-01-01), Fahrenkrug
patent: 4935287 (1990-06-01), Johnson et al.

Affiliated with

Also associated with

Rating

Multilayered elastic sheet structure and process for producing a does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Multilayered elastic sheet structure and process for producing a, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Multilayered elastic sheet structure and process for producing a will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1831635