Full-surface bonded multiple component melt-spun nonwoven web
AssigneeE.I. du Pont de Nemors and Company
InventorsVishal Bansal, Hyun Sung Lim, David Matthews Laura, Jr.
Life of this patent
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Abstract
A full-surface bonded multiple component nonwoven fabric is provided that has an improved combination of tear strength and tensile strength at lower thicknesses than known in the art. The full-surface bonded multiple component webs have a void percent between about 3% and 56% and a Frazier permeability of at least 0.155 m3/min-m2. The full-surface bonded multiple component nonwoven fabrics can be prepared in a smooth-calendering process.
Claims19
A full-surface bonded multiple component nonwoven fabric comprising a full-surface bonded nonwoven sheet consisting of melt-spun multiple component fibers selected from the group consisting of multiple component staple fibers, multiple component continuous fibers, and combinations thereof, the multiple component fibers having a cross-section and a length, and comprising a first polymeric component and a second polymeric component, the first and second polymeric components being arranged in substantially constantly positioned distinct zones across the cross-section of the multiple component fibers and extending substantially continuously along the length of the multiple component fibers, wherein the second polymeric component has a melting point that is at least about 10° C. lower than the melting point of the first polymeric component and wherein at least a portion of the outer peripheral surface of the multiple component filaments comprises the second polymeric component, a ratio of average strip tensile strength to basis weight of at least 1.05 N/gsm, and a ratio of average trap tear strength to basis weight of at least 0.329 N/gsm.
A process for preparing a thermally bonded multiple component nonwoven fabric comprising the steps of:
- a. providing a multiple component nonwoven fabric having a first outer surface and an opposing second outer surface, the multiple component nonwoven fabric consisting of multiple component melt-spun fibers selected from the group consisting of multiple component staple fibers, multiple component continuous fibers, and combinations thereof, the multiple component fibers having a cross-section and a length, and comprising a first polymeric component and a second polymeric component, the first and second polymeric components being arranged in substantially constantly positioned distinct zones across the cross-section of the multiple component fibers and extending substantially continuously along the length of the multiple component fibers, wherein the second polymeric component has a melting point, Tm, that is at least about 10° C. lower than the melting point of first polymeric component and at least a portion of the outer peripheral surface of the multiple component filaments comprises the second polymeric component;
- b. pre-heating the first and second outer surfaces of the multiple component nonwoven fabric to a temperature between 35° C. and (Tm-40)° C.;
- c. full-surface bonding the first outer surface of the nonwoven fabric by passing the pre-heated nonwoven fabric through a first nip formed by first and second smooth-surfaced calender rolls wherein the second roll is unheated and the first roll contacts the first outer surface of the nonwoven fabric and is maintained at a temperature no greater than (Tm-40)° C., while applying a nip pressure between about 17.5 to about 70 N/mm;
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- d. full-surface bonding the second outer surface of the nonwoven fabric by passing the nonwoven fabric through a second nip formed by third and fourth smooth-surfaced calender rolls wherein the fourth roll is unheated and the third roll contacts the second outer surface of the nonwoven fabric and is maintained at a temperature no greater than (Tm-40)° C. while applying a nip pressure between about 17.5 to about 70 N/mm.
A process for preparing a thermally bonded multiple component nonwoven fabric comprising the steps of:
- a. providing a multiple component nonwoven fabric having a first outer surface and an opposing second outer surface, the multiple component nonwoven fabric consisting of multiple component melt-spun fibers selected from the group consisting of multiple component staple fibers, multiple component continuous fibers, and combinations thereof the multiple component fibers having a cross-section and a length, the multiple component fibers comprising a first polymeric component and a second polymeric component, the first and second polymeric components being arranged in substantially constantly positioned distinct zones across the cross-section of the multiple component fibers and extending substantially continuously along the length of the multiple component fibers, wherein the second polymeric component has a melting point, Tm, that is at least about 10° C. lower than the melting point of first polymeric component and at least a portion of the outer peripheral surface of the multiple component filaments comprises the second polymeric component;
- b. pre-heating the first outer surface of the multiple component nonwoven fabric to a temperature between 35° C. and (Tm−40)° C.;
- c. full-surface bonding the first outer surface of the multiple component nonwoven fabric by passing the pre-heated nonwoven fabric through a first nip formed by first and second smooth-surfaced calender rolls wherein the second roll is unheated and the first roll contacts the first outer surface of the nonwoven fabric and Is maintained at a temperature no greater than (Tm-40)° C.;, while applying a first nip pressure between about 17.5 to about 70 N/mm;
- d. pre-heating the second outer surface of the multiple component nonwoven fabric to a temperature between 35° C. and (Tm-40)° C.;
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- e. full-surface bonding the second outer surface of the nonwoven fabric by passing the twice pre-heated nonwoven fabric through a second nip formed by third and fourth smooth-surfaced calender rolls wherein the fourth roll is unheated and the third roll contacts the second outer surface of the nonwoven fabric and is maintained at a temperature no greater than (Tm-40)° C., while applying a second nip pressure between about 17.5 to about 70 N/mm.
Dependencies are inferred from the claim text.