Method for production of a hydroentangled airlaid web and products obtained therefrom

• US 9,394,637 B2
• Filed: 07/16/2013
• Issued: 07/19/2016
• Est. Priority Date: 12/13/2012
• Status: Active Grant

• Current Assignee: Glatfelter Holding AG
• Original Assignee: Jacob Holm & Sons AG (Glatfelter Corp.)
• Inventors: Knowlson, Richard, Petersen, Katherine Dyrmose, Mariani, Eric
• Primary Examiner(s): VANATTA, AMY B
• Application Number:
  US13/943,146
• Publication Number:
  US 20140170402A1
• Time in Patent Office: 1,099 Days
• Field of Search: 281/04, 281/05
• US Class Current: 1/1
• CPC Class Codes: A61K 8/0208 Tissues; Wipes; Patches
• CPC Class Codes: B08B 1/143 Wipes
• CPC Class Codes: D04H 1/425 Cellulose series
• CPC Class Codes: D04H 1/4258 Regenerated cellulose series
• CPC Class Codes: D04H 1/43835 Mixed fibres, e.g. at least two chemically different fibres or fibre blends
• CPC Class Codes: D04H 1/46 by needling or like operations to cause entanglement of fibres D04H1/45 takes precedence; needling machines D04H18/00
• CPC Class Codes: D04H 1/492 by fluid jet D04H1/49 takes precedence
• CPC Class Codes: D04H 5/03 by fluid jet
• CPC Class Codes: D10B 2201/01 Natural vegetable fibres
• CPC Class Codes: D10B 2509/026 Absorbent pads; Tampons; Laundry; Towels

Abstract

A method to prepare nonwoven webs which have good MD and CD strength, and are water disposable is provided. The method includes hydroentangling an airlaid web of no less than 50% by weight of natural cellulose fibers having a fiber length of no more than 3.5 mm and no more than 50% by weight staple fibers having a fiber length of no less than 8.0 mm. The airlaid web is not laid on a precursor web and no adhesive, binder or thermal bonding fibers are utilized. The airlayering and hydroentangling are conducted in a continuous operation. Products may be obtained according to the method of this invention that meet municipal guidelines for flushability.

Claims

1. A method for production of a nonwoven web, comprising:

preparing a homogeneous dry mixture of defibrated natural cellulose fibers and staple fibers;

passing the homogeneous dry mixture through a perforated cylinder onto a foraminous carrier to airform the mixture to obtain at least one homogeneous airlaid web;

hydroentangling the airlaid web on the foraminous carrier to consolidate the web on at least one side; and

drying the hydroentangled web to obtain the nonwoven web;

wherein

the airforming and hydroentangling is conducted in a continuous operation,

a content of the natural cellulose fibers in the mixture of fibers is no less than 50% by weight and a content of the staple fibers is no more than 50% by weight,

no binder, adhesive or thermal bonding fibers are utilized,

a fiber length of the natural cellulose fibers is no more than 3.5 mm,

a fiber length of the staple fibers is no less than 8.0 mm,

a basis weight of the nonwoven web is from 20 g/m² to 100 g/m², and

a thickness of the nonwoven web is from 0.25 mm to 2 mm.

2. The method according to claim 1 wherein the content of natural cellulose fibers in the mixture is at least 75% by weight and the content of the staple fibers is 25% or less by weight.

3. The method according to claim 1 wherein the basis weight is from 40 g/m² to 60 g/m².

4. The method according to claim 1 wherein the natural cellulose fiber is wood pulp and the staple fiber is viscose or lyocell.

5. The method according to claim 4, wherein the wood pulp is a sulfite pulp obtained by sulfite pulping.

6. The method of claim 1 wherein the airlaid web is hydroentangled to consolidate the web on both sides.

7. The method of claim 1 wherein an applied pressure of the hydroentanglement is from 0.04 bars/kg/h/m to 15 bars/kg/h/m.

8. The method of claim 7 wherein the applied pressure of the hydroentanglement is from 0.3 bars/kg/h/m to 4 bars/kg/h/m.

9. The method according to claim 1, further comprising:

embossing the hydroentangled web;

wherein the embossing operation is continuous with the airforming and hydroentangling.

10. The method according to claim 1, wherein the airforming of the airlaid web is conducted in a single airformer.

11. The method according to claim 1, wherein the airforming of the airlaid web is conducted in more than one airformer and the fiber content of each web is the same.

12. The method according to claim 1, wherein the airforming of the airlaid web is conducted in more than one airformer and a fiber content of at least one web is different from the fiber content of another web.

13. The method according to claim 1, wherein no binder, adhesive or thermal bonding is applied to the nonwoven web.

14. The method according to claim 1, wherein the airlaid web is directly formed on a carrier of the airformer without preforming a precursor web or incorporating a continuous filament web.

15. The method according to claim 1, wherein a pressure of the hydroentanglement of the airlaid web is from 0.35 bars/kg/h/m to 15 bars/kg/h/m.

16. The method according to claim 15, wherein no adhesive, binder or binder fiber is applied to the nonwoven web and a ratio of tensile strength in a machine direction to tensile strength in a direction perpendicular to the machine direction (MD/CD) is less than 3.