Plastic and nonmetallic article shaping or treating: processes – Direct application of fluid pressure differential to... – Bulk deposition of particles by differential fluid pressure
Reexamination Certificate
1998-08-05
2001-07-03
Theisen, Mary Lynn (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Direct application of fluid pressure differential to...
Bulk deposition of particles by differential fluid pressure
C264S113000, C156S167000
Reexamination Certificate
active
06254821
ABSTRACT:
It is known from U.S. Pat. No. 4,118,531 to use crimped fibers to produce a bulked fleece. For this purpose, the crimped fibers are laid down in a stream together with other smooth fibers. However, since such a fleece must be compacted, the fleece must be mechanically compressed, causing it to lose a significant part of its volume once again.
It is known from U.S. Pat. No. 5,108,820 to use bicomponent fibers to make a bulked fleece, with the components of these fibers shrinking differently when heated, and with the fibers crimping three-dimensionally. These fibers or other single-component fibers that crimp under the influence of heat are laid down together with other fibers to form a fleece which must however be compressed by pressure for compaction, so that it loses volume.
Another use of bicomponent fibers is described in EP-A-0 171 806 or 0 171 807. In that case, the bicomponent fibers laid down with other fibers to produce a first compaction is subjected to thin streams of water and then the fleece product is heated to the sticking or melting temperature of one component of the bicomponent fiber so that this molten component connects permanently to the other fibers, producing a second compaction. In this way, a fleece product can be produced that is solid but not bulked.
A bonded fleece that is both bulked and permeable to liquid is used in the hygienic products industry. In diapers or other hygienic products, a fluid buffer must initially be provided that ensures drainage of the excreted body fluid into the absorber located adjacent thereto in the transverse and also, and especially, in the lengthwise direction. The liquid buffer must quickly absorb the liquid flowing out and then pass it on slowly to the adjacent absorber over its entire surface.
The goal of the invention is to develop an economical method by which a bulked and sufficiently compacted fleece can be produced without the aid of chemical binders or gluing, said fleece having sufficient room for rapid absorption of the excreted liquid and distributing the liquid uniformly over the surface of the fleece for drainage. As a result, the adjacent absorber has the ability to absorb the liquid slowly and completely from this volume.
To achieve this stated goal, the invention provides that a fleece is formed from shrunk and/or crimped fibers together with non-shrinking manmade fibers, the fleece is then compacted using a hydrodynamic compaction method without using binders, and the fleece is then dried, and then at this point and/or subsequently, the shrinkage present in the shrunk fibers and/or the crimping ability present in the crimped fibers in latent form are triggered by the action of heat. If the shrinkage or crimping is to be triggered chemically, this processing step likewise comes under the subject of the invention. A fleece of this kind is bulked because of the way it is made. The volume increases only slightly as a result of water needling, but resumes its volume as a result of the shrinkage or crimping of the fibers, in such fashion that the new fleece is optimally correct at its point of application for the properties desired of hygienic products.
The fleece can be made of staple fibers and/or endless fibers. The shrunk and/or crimped fibers can be mixed in advance with the fibers that do not change, or the layer of fibers that change under the influence of heat can be applied on one or both sides. Advantageously, bicomponent fibers of the “side by side” type are used (U.S. Pat. No. 5,108,820), with a fiber component deposited laterally on the fibers undergoing a change in length under the influence of temperature. As a result, the fiber is deformed three-dimensionally overall, so that fleece becomes compacted and bulkier. The same applies to the pure shrunk fibers (monopolymers) which according to the invention is [sic] water-needled with non-shrinking fibers so that after the shrinking process, the entire fiber fleece changes so that it has more volume. The pile weight can be between 3 and 60 g/m
2
with a fiber titer of 1.3-6.7 dtex.
REFERENCES:
patent: 4118531 (1978-10-01), Hauser
patent: 4568581 (1986-02-01), Peoples, Jr.
patent: 4783231 (1988-11-01), Raley
patent: 5108820 (1992-04-01), Kaneko et al.
patent: 5396689 (1995-03-01), Vuillaume
patent: 5701643 (1997-12-01), Fleissner
patent: 0171806 (1986-02-01), None
patent: 0171807 (1986-02-01), None
Antonelli Terry Stout & Kraus LLP
Fleissner GmbH & Co. Maschinenfabrik
Theisen Mary Lynn
LandOfFree
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