Production process of a nonwoven fabric sheet

Patent metadata

Field	Value
Publication number	US-9315931-B2
Application number	US-201414193904-A
Country	US
Kind code	B2
Filing date	Feb 28, 2014
Priority date	Mar 29, 2010
Publication date	Apr 19, 2016
Grant date	Apr 19, 2016

Abstract

A sheet of nonwoven fabric which has surface irregularities, the shape of the surface irregularities being less apt to be changed by external pressure, etc. The sheet has a machine, cross and thickness directions which are perpendicular to one another. The upper surface has a plurality of protrusions continuously extending, in parallel, in the cross direction and further has a plurality of recesses that are located between the adjacent protrusions and extend in the cross direction. The sheet includes first and second fibrous layers located on the upper-surface side and the lower-surface side, respectively. The first fibrous layer comprises heat-fusible fibers, and the second fibrous layer comprises coil-shaped three-dimensional crimp fibers that are oriented mainly in the machine direction and form a network by entanglement thereof without having been fused at the sites where the crimp fibers cross one another.

First claim

The invention claimed is:

1. A method of processing a non-woven fabric sheet, comprising the steps of:
a) opening a first fiber assembly containing heat-fusible fibers by passing the first fiber assembly through a carding machine to form a web containing heat-fusible fibers,
b) opening a second fiber assembly containing latent crimpable fibers by passing the second fiber assembly through a carding machine to form a web containing latent crimpable fibers,
c) superimposing the web containing heat-fusible fibers and the web containing latent crimpable fibers to form a laminated web,
d) creating a difference in shrinkage force in the machine direction in the laminated web by causing crimping of the latent crimpable fibers during a heat treatment step over a prescribed width in the machine direction,
f) heating the laminated web to a temperature that: i) is lower than the fusing temperature of the heat-fusible fibers; and ii) causes crimping of the latent crimpable fibers by lowering resistance to crimping of the latent crimpable fibers, and
g) fusing the web obtained in step f at sites where the heat-fusible fibers mutually intersect by heating to a temperature equal to or higher than the fusing temperature of the heat-fusible fibers.

2. The method of processing a non-woven fabric sheet according to claim 1 , wherein in step d the laminated web is transported by placing on a support having liquid passage portions and protruding liquid blocking portions extending in parallel in the cross-machine direction CD and alternately repeating in the machine direction MD, and fibers in the laminated web are reoriented by spraying a liquid from a plurality of nozzles arranged in the cross-machine direction.

3. The method of processing a non-woven fabric sheet according to claim 2 , wherein in step f the lowering of resistance to crimping of the latent crimpable fibers is achieved by transporting the laminated web in step f at a lower transport speed than that of a previous step.

4. The method of processing a non-woven fabric sheet according to claim 3 , wherein in step f the lowering of resistance to crimping of the latent crimpable fibers is achieved heat treating the laminated web in a floating dryer.

5. The method of processing a non-woven fabric sheet according to claim 3 , further comprising the step of:
e) transporting the web obtained in step d to step f between step d and step f.

6. The method of processing a non-woven fabric sheet according to claim 2 , wherein in step f the lowering of resistance to crimping of the latent crimpable fibers is achieved heat treating the laminated web in a floating dryer.

7. The method of processing a non-woven fabric sheet according to claim 6 , further comprising the step of:
e) transporting the web obtained in step d to step f between step d and step f.

8. The method of processing a non-woven fabric sheet according to claim 2 , further comprising the step of:
e) transporting the web obtained in step d to step f between step d and step f.

9. The method of processing a non-woven fabric sheet according to claim 2 , further comprising the step of:
h) cooling the web obtained in step g after step g.

10. The method of processing a non-woven fabric sheet according to claim 1 , wherein in step f the lowering of resistance to crimping of the latent crimpable fibers is achieved by transporting the laminated web in step f at a lower transport speed than that of a previous step.

11. The method of processing a non-woven fabric sheet according to claim 10 , wherein in step f the lowering of resistance to crimping of the latent crimpable fibers is achieved heat treating the laminated web in a floating dryer.

12. The method of processing a non-woven fabric sheet according to claim 11 , further comprising the step of:
e) transporting the web obtained in step d to step f between step d and step f.

13. The method of processing a non-woven fabric sheet according to claim 10 , further comprising the step of:
e) transporting the web obtained in step d to step f between step d and step f.

14. The method of processing a non-woven fabric sheet according to claim 10 , further comprising the step of:
h) cooling the web obtained in step g after step g.

15. The method of processing a non-woven fabric sheet according to claim 1 , wherein in step f the lowering of resistance to crimping of the latent crimpable fibers is achieved by heat treating the laminated web in a floating dryer.

16. The method of processing a non-woven fabric sheet according to claim 15 , further comprising the step of:
e) transporting the web obtained in step d to step f between step d and step f.

17. The method of processing a non-woven fabric sheet according to claim 15 , further comprising the step of:
h) cooling the web obtained in step g after step g.

18. The method of processing a non-woven fabric sheet according to claim 1 , further comprising the step of:
e) transporting the web obtained in step d to step f between step d and step f.

19. The method of processing a non-woven fabric sheet according to claim 18 , further comprising the step of:
h) cooling the web obtained in step g after step g.

20. The method of processing a non-woven fabric sheet according to claim 1 , further comprising the step of:
h) cooling the web obtained in step g after step g.

Assignees

• Unicharm Corp

Inventors

• Uematsu Katsuhiro
• Oba Toru
• Mizutani Satoshi

Classifications

• D04H1/4391

  characterised by the shape of the fibres · CPC title

• Y10T428/2457

  Parallel ribs and/or grooves · CPC title

• D04H1/482

  in combination with shrinkage · CPC title

• A61F13/15699

  Forming webs by bringing together several webs, e.g. by laminating or folding several webs, with or without additional treatment of the webs · CPC title

• A61F2013/15878

  by thermal bonding · CPC title