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EP-4178525-B1 - ABSORBENT PRODUCT WITH IMPROVED CAPILLARY PRESSURE AND SATURATION CAPACITY

EP4178525B1EP 4178525 B1EP4178525 B1EP 4178525B1EP-4178525-B1

Inventors

  • COLMAN, CHARLES W.
  • BAKER, JOSEPH K.
  • BAKER, ANDREW T.
  • RANGANATHAN, SRIDHAR
  • CAVANAUGH, Thomas

Dates

Publication Date
20260506
Application Date
20210331

Claims (15)

  1. A multi-layer fibrous web (100) comprising: a first layer (102); a second layer (104) having a capillary pressure that is less than a capillary pressure of the first layer (102); and a crossover zone (106) at an interface of the first layer (102) and the second layer (104), where a capillary pressure of the crossover zone (106) is between the capillary pressure of the first layer (102) and the capillary pressure of the second layer (104), wherein both the first layer (102) and the second layer (104) are a foam formed layer, wherein the crossover zone (106) comprises about 5 wt.% to about 50 wt.% of the multi-layer fibrous web (100), wherein the first foam formed layer (102) comprises pulp fibers, and wherein the second foam formed layer (104) comprises elastomeric polymer fibers.
  2. The multi-layer fibrous web (100) as defined in claim 1, wherein the crossover zone (106) includes first foam formed layer fibers and second foam formed layer fibers.
  3. The multi-layer fibrous web (100) as defined in claim 1 or 2, wherein the multi-layer fibrous web exhibits an absorbent capacity as measured using a Gravimetric Absorbency Testing System (GATS) according to the M/K system GATS test using Analysis Program Version 4.3.4, of about 5.5 grams of fluid per gram of wipe (g/g) or greater.
  4. The multi-layer fibrous web (100) as defined in any one of claims 1-3, wherein the multi-layer fibrous web exhibits an absorbent rate as measured using a Gravimetric Absorbency Testing System (GATS) according to the M/K system GATS test using Analysis Program Version 4.3.4, of about 1.6 ((g/g)*sec 0.5 ) or greater.
  5. The multi-layer fibrous web (100) as defined in any one of claims 1-4, wherein the second foam formed layer (104) comprises at least about 10% by dry weight of the multi-layer fibrous web (100).
  6. The multi-layer fibrous web (100) as defined in any one of claims 1-5, wherein the first foam formed layer (102) has a capillary pressure at 0% saturation of greater than 33 kilopascals, measured according to the method as described herein.
  7. The multi-layer fibrous web (100) as defined in any one of claims 1-6, wherein the second foam formed layer (104) has a capillary pressure at 0% saturation of less than 33 kilopascals, measured according to the method as described herein.
  8. A wiping product comprising the multi-layer fibrous web (100) as defined in any one of claims 1-7.
  9. An absorbent article comprising the multi-layer fibrous web (100) as defined in any one of claims 1-7.
  10. A method of forming a multi-layer fibrous web (100), comprising; forming a first foam formed layer (102); and forming a second foam formed layer (104) having a capillary pressure that is less than a capillary pressure of the first foam formed layer (102), wherein the first foam formed layer (102) and second foam formed layer (104) are formed using a headbox (200); wherein the headbox (200) comprises at least one lamella (208), and wherein the at least one lamella (208) is at least partially retracted from the headbox (200).
  11. The method of claim 10, wherein the lamella (208) is retracted to a position sufficient to allow mixing of a portion of first foam formed layer fibers and a portion of second foam formed layer fibers in the headbox (200), forming the first foam formed layer (102), the second foam formed layer (104), and a crossover zone (106).
  12. The method of claim 10 or 11, wherein the first foam formed layer fibers and the second foam formed layer fibers are provided to a single headbox (200) as a suspension of first foam formed layer fibers and a suspension of second foam formed layer fibers.
  13. The method of any of claims 10-12, wherein at least one of the first foam formed layer (102) and the second foam formed layer (104) is formed using a ratio of jet speed to forming fabric speed of about 0.5:1 to about 5:1.
  14. The method of any of claims 10-13, wherein the crossover zone (106) comprises first foam formed layer fibers and second foam formed layer fibers, and comprises about 5 wt.% to about 50 wt.% of the multi-layer fibrous web (100).
  15. The method of any of claims 10-14, wherein the first foam formed layer (102) has a capillary pressure at 0% saturation of greater than 33 kilopascals, and/or the second foam formed layer (104) has a capillary pressure at 0% saturation of less than 33 kilopascals, measured according to the method as described herein.

Description

BACKGROUND Conventional absorbent articles, including wiping products have been made from woven and knitted fabrics. Such wipers have been used in all different types of industries, such as for industrial applications, food service applications, health and medical applications, and for general consumer use. Conventional rags and washcloths can be reusable if laundered properly. Disposable wipers, however, continue to gain in popularity and are readily displacing many conventional woven or knitted products. Disposable wipers, for instance, can offer many advantages. For example, disposable wipers are generally more sterile, as they are generally free of debris and contaminants. Laundered rags and washcloths, for instance, can still contain residual debris from past use and can also pick up debris during the laundering process. In addition, laundering woven or knitted wipers can not only create a great expense, but also requires the use of copious amounts of water and detergents that must be properly disposed of. Further, in many applications, especially in the industrial setting, conventional cloth wipers are disposed of after a single use due to the chemicals and other debris that come into contact with the wiper. However, disposable wipers often suffer from a tradeoff between being able to quickly absorb water or other fluids from a surface and being able to store a large volume of fluid. For instance, a wiper may be formed with a structure and fibers suitable for improved capillary pressure (which improves the force that drives fluid into the wipe for improved pick up speed), but, such a structure and fiber selection sacrifices void volume, which determines the fluid capacity of the wipe. Additionally, conventional wipers also suffer from a decrease in pick-up speed with increased saturation. Thus, as the liquid saturation of the wiper increases, the capillary pressure of the wiper decreases, which in turn decreases the pick-up speed Furthermore, it was found that a layered wiper approach also failed to produce a wiper with good pick-up speed and good liquid capacity. Particularly, as discussed briefly above, wipers or wiper layers configured for improved pick-up speed often exhibit high capillary pressures at low saturation, while wipers configured for high absorbent capacity exhibit very low capillary pressure, even at low saturation. However, surprisingly, when a wiper was formed with a high pick-up speed layer adjacent to a high absorbent capacity layer, it was found that the interface between the layers exhibited a capillary pressure that was lower than either of the two adjacent layers, which resulted in no improvement in performance, even though two separate layers were combined. Particularly, it is believed that no improvement in either pick-up speed or absorbent capacity was observed as fluid was unable to transfer from the high pick-up layer to the high absorbent capacity layer. Therefore, it would be a benefit to provide an absorbent article, such as a wiper that has improved absorbent capacity while maintaining good fluid pick-up. Furthermore, it would also be advantageous to provide a method for providing an absorbent article with a crossover zone having a capillary pressure greater than one of the two adjacent layers. It would also be a benefit to provide a wiper with an increased fluid-pick up speed. Furthermore, it would be advantageous to provide a wiper with improved fluid-pick up speed even when the wiper is at least partially saturated. EP 0496524 A1 discloses a foam-formed nonlaminated stratified paper tissue with two foamed layers containing pulp fibers. SUMMARY The present disclosure is generally directed to a multi-layer fibrous web, as defined in claim 1. The multi-layer fibrous web includes a first layer, a second layer, and a crossover zone at an interface of the first layer and the second layer. The second layer has a capillary pressure that is less than a capillary pressure of the first layer, and the crossover zone has a capillary pressure between the capillary pressure of the first layer and the capillary pressure of the second layer. Both the first layer and the second layer are a foam formed layer. The present disclosure is also directed to a wiping product comprising the multi-layer fibrous web, as defined in claim 8, and to an absorbent article comprising the multi-layer fibrous web, as defined in claim 9. The first foam formed layer comprises pulp fibers. The second foam formed layer comprises elastomeric polymer fibers. In one aspect, the crossover zone includes first foam formed layer fibers and second foam formed layer fibers. In another aspect, the wiping product exhibits an absorbent capacity as measured using a Gravimetric Absorbency Testing System (GATS) according to the M/K system GATS test using Analysis Program Version 4.3.4, of about 5.5 grams of fluid per gram of wipe (g/g) or greater. In yet a further aspect, the wiping product exhibits an absorbent rate as