Unitary stratified composite

• US 7,125,470 B2
• Filed: 11/13/2002
• Issued: 10/24/2006
• Est. Priority Date: 12/06/1996
• Status: Expired due to Fees

• Current Assignee: National Institute for Strategic Technology Acquisition and Commercialization
• Original Assignee: National Institute for Strategic Technology Acquisition and Commercialization
• Inventors: Miller, Charles E., Mathews, Jeffrey D., Naieni, Shahrokh A., Graef, Peter A., Howard, Fred B., Bunker, Daniel T., Elston, Colin
• Primary Examiner(s): HUG, JOHN ERIC
• Application Number:
  US10/294,242
• Publication Number:
  US 20030130633A1
• Time in Patent Office: 1,441 Days
• Field of Search: 162/146, 162/129, 162/123, 162/125, 162/127, 162/157.6, 162/158, 162/157.2, 162/204, 162/207, 428152-154, 604365-367, 604/370, 604/374, 604/375, 604/378
• US Class Current: 162/129
• CPC Class Codes: A61F 13/531 having a homogeneous composition through the thickness of the pad A61F13/538, A61F13/539 take precedence
• CPC Class Codes: A61F 13/534 having an inhomogeneous composition through the thickness of the pad A61F13/538, A61F13/539 take precedence; homogeneous cores with tissue wrapping A61F13/53
• CPC Class Codes: A61F 13/537 characterised by a layer facilitating or inhibiting flow in one direction or plane, e.g. a wicking layer A61F13/538 takes precedence
• CPC Class Codes: A61F 13/539 characterised by the connection of the absorbent layers with each other or with the outer layers
• CPC Class Codes: B32B 2262/0253 Polyolefin fibres
• CPC Class Codes: B32B 2262/0261 Polyamide fibres
• CPC Class Codes: B32B 2262/0284 Polyethylene terephthalate [PET] or polybutylene terephthalate [PBT]
• CPC Class Codes: B32B 2262/04 Cellulosic plastic fibres, e.g. rayon
• CPC Class Codes: B32B 2307/726 Permeability to liquids, absorption
• CPC Class Codes: B32B 2307/73 Hydrophobic
• CPC Class Codes: B32B 2555/02 Diapers or napkins
• CPC Class Codes: B32B 5/04 characterised by a layer being specifically extensible by reason of its structure or arrangement , e.g. by reason of the chemical nature of the fibres or filaments
• CPC Class Codes: B32B 5/26 another layer next to it also being fibrous or filamentary relative arrangement of fibres or filaments of different layers B32B5/12
• CPC Class Codes: Y10T 428/249943 Fiber is nonlinear [e.g., crimped, sinusoidal, etc.]
• CPC Class Codes: Y10T 428/249949 Two or more chemically different fibers

Abstract

A unitary stratified composite composed of a first stratum and a second stratum integrally connected by a transition zone is disclosed. The first stratum serves as a liquid acquisition stratum that rapidly acquires and then transfers liquid to the second stratum. The second stratum serves to withdraw liquid from the first stratum and further serves as a temporary storage stratum. Methods for forming the unitary stratified composite are also disclosed.

Claims

1. A method for forming an unitary stratified composite comprising the steps of:

combining synthetic fibers and a binder to provide a first fibrous mixture;

combining crosslinked cellulosic fibers, a superabsorbent polymer and a binder to provide a second fibrous mixture;

depositing the first fibrous mixture on a foraminous support to form a first stratum;

depositing the second fibrous mixture on the first fibrous mixture on the foraminous support to form a second stratum thereby providing a stratified fibrous composite, said composite further comprising a transition zone intermediate and coextensive with the first and second strata, the transition zone comprising fibers from the first and second strata commingled substantially uniformly across the composite'"'"'s width and along the composite'"'"'s length; and

heating the stratified fibrous composite to effect thermal bonding between the fibers and binder to provide a unitary stratified composite.

2. The method of claim 1 wherein the step of combining crosslinked cellulosic fibers, superabsorbent polymer, and a binder to provide a second fibrous mixture further comprises combining cellulosic fibers with said crosslinked fibers, superabsorbent polymer, and binder.

3. The method of claim 1 wherein the first fibrous mixture is an aqueous slurry.

4. The method of claim 1 wherein the second fibrous mixture is an aqueous slurry.

5. The method of claim 1 further comprising the step of removing water from the stratified fibrous composite.

6. The method of claim 1 wherein the synthetic fibers are selected from the group consisting of polyethylene terephthalate, polyethylene, polypropylene, nylon, latex, rayon fibers, and mixtures thereof.

7. The method of claim 1 wherein the binder comprises a multicomponent binding fiber.

8. The method of claim 1 wherein the first fibrous mixture and the second fibrous mixture are deposited on the foraminous support substantially simultaneously.

9. The method of claim 1 wherein the first fibrous mixture is deposited by an offset headbox.

10. The method of claim 1 wherein the second fibrous mixture is deposited by an offset headbox.

11. The method of claim 1 wherein the foraminous support is a forming wire.

12. The method of claim 1 wherein the mixing of the fibers of first and second fibrous mixtures is enhanced through the application of vacuum to the foraminous support.