Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Patent
1998-12-22
2000-10-24
Yao, Sam Chuan
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
156181, 156209, 156229, 26417315, 2642108, 264284, 2642905, 264DIG73, D04H 154, D04H 316
Patent
active
061361240
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention concerns a method of manufacturing a bulky textured non-woven. The method comprises the steps of: have been stretched and deposited in the form of a skein of fibers, between a pair of rollers, and
A method of this type is known from U.S. Pat. No. 5,399,174. This patent describes a laminated sheet comprising a non-woven layer of bunches of kinked polymeric fibers bonded to a sheet of polymer. Rollers impress a bonding and decorative pattern that connects the non-woven to the sheet.
The same patent's Background of the Invention mentions that roller impressing is one method of modifying a non-woven's feel while simultaneously producing a decorative pattern. The patent also refers to the U.S. Pat. No. 4,592,943 which relates a method whereby a non-woven is heated while the sheet being processed travels between two gratings that transfer their patterns to the non-woven. Also mentioned is the U.S. Pat. No. 4,774,124 that discloses a patterned-roller impression method.
Common to all these methods is that a bulky layer of non-woven must be initially produced before being impressed with a pattern. The layer of non-woven, however, decreases rather than increases in bulk.
SUMMARY OF THE INVENTION
The principal object of the present invention is accordingly to provide a spin-bonded non-woven that has its already deposited fibers and filaments partly bonded together as a result of the deposition itself with a definite increase in bulk and with "three-dimensionality" by subsequently processing the web of semifinished non-woven in a novel way with the second pair of rollers.
This object is attained, in accordance with the present invention, in the generic method set forth above by initially stretching the separate filaments to a range from 50 to 70% of their maximal possible extension (i.e., just before their breaking point) during step (a) and subsequently processing the semifinished non-woven during step (c) between a pair of rollers comprising a positive roller, specifically a roller with elevations distributed over its surface, and a negative roller, specifically a roller with the same number depressions distributed over its surface such that the elevations in the first roller engage the depressions in the second roller, stretching the non-woven further in the vicinity of the positive
egative roller engagement.
The method in accordance with the present invention results in spin-bonded non-wovens that are essentially better than those manufactured in accordance with the classical method. The fibers in both the semifinished non-wovens and in the final products manufactured by the classical method are deposited essential two-dimensionally. These materials can accordingly be considered paper-like, and their fibers can be oriented three-dimensionally at the state of the art only by expensive and to some extent complicated additional processing.
Obtaining a bulky deposit by using highly kinked fibers (staple fibers) is admittedly known. Still, such materials will not have a cloth-like feel unless further processed. Furthermore, the physical properties of kinked staple fibers can often not be exploited in spin-bonded non-wovens.
Spin-bonded non-wovens are manufactured by extruding a molten polymer, usually polyethylene, polypropylene, or polyamide. The melt is homogenized, filtered, and conveyed to one or more viscose pumps that supplies it to spinnerets at uniform pressure. The melt is forced through the spinnerets at constant pressure and cooled. The separate filaments are uniformly stretched in a separate process and deposited onto a traveling belt. The result is a skein that is essentially two-dimensionally oriented. The skein is conveyed to a pair of rollers, usually comprising a rough and a smooth steel roller, that partly fuse the skein to augment its two-dimensionality. The result is the "semifinished" non-woven.
The method in accordance with the present invention results in a highly stretchable and bulky non-woven. The elevations and depressions can be exploite
REFERENCES:
patent: 4592943 (1986-06-01), Cancian et al.
patent: 4774124 (1988-09-01), Shimalla et al.
HCD Hygienic Composites Development GmbH
Yao Sam Chuan
LandOfFree
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