Voluminous nonwoven composite and method for producing same

Abstract

A voluminous nonwoven composite includes a first layer of melt spun endless filaments, which are randomly deposited, and a second layer of crimped staple fibers and a method produces same. The endless filaments have a fineness of 0.8 to 1.8 dtex, preferably of 1.3 dtex, particularly preferably of 1.0 to 1.2 dtex, the crimped staple fibers have a fineness of 2.2 to 15 dtex, preferably of 4 to 10 dtex, and the layers are stabilized and intimately connected with one another exclusively by water jets, to form the voluminous nonwoven composite.

Claims

1. Voluminous nonwoven composite comprising a first layer of melt-spun endless filaments, laid down in entangled manner, and a second layer of crimped staple fibers, wherein a) the endless filaments have a fineness of 0.8 to 1.3 dtex, b) the crimped staple fibers have a fineness of 2.2 to 15 dtex, and c) the layers are stabilized and intimately connected with one another exclusively via water jets, to form the voluminous nonwoven composite.

2. Nonwoven composite according to claim 1, wherein the crimped staple fibers have a length of 2.5 cm.

3. Nonwoven composite according to claim 1, wherein the density of the nonwoven composite amounts to 0.1 g/cm.sup.3.

4. Nonwoven composite according to claim 1, wherein the nonwoven composite has pores having a diameter of 0.4 mm.

5. Nonwoven composite according to claim 1, wherein it has a weight per surface area of 18 to 80 g/m.sup.2.

6. Nonwoven composite according to claim 1, wherein it has a relief having discrete raised locations, which are embossed during water-jet stabilization.

7. Nonwoven composite according to claim 1, wherein it has an additional embossing, which are introduced via a thermo-calender and/or an ultrasound calender.

8. Nonwoven composite according to claim 1, wherein the endless filaments and/or the crimped staple fibers are passed to water-jet stabilization in an inline process.

9. Nonwoven composite according to claim 1, wherein the first layer and/or the second layer are pre-stabilized.

10. Nonwoven composite according to claim 9, wherein both the first layer and the second layer are pre-stabilized, are produced separately from one another, and then are passed to water-jet stabilization.

11. Nonwoven composite according to claim 1, wherein the first layer and/or the second layer are passed to water-jet stabilization in an offline process.

12. Nonwoven composite according to claim 1, wherein at least one additional layer of endless filaments and/or staple fibers are passed to water-jet stabilization.

13. Nonwoven composite according to claim 1, wherein the endless filaments comprise monofilaments or bi-component filaments composed of polypropylene, polyethylene, polyester, polyamide, polylactide or their copolymers.

14. Nonwoven composite according to claim 1, wherein the staple fibers comprise viscose or cotton or of mono-component or bi-component fibers composed of polypropylene, polyethylene, polyester, polyamide, polylactide or their copolymers.

15. Nonwoven composite according to claim 1, wherein the crimped staple fibers have a fineness of 4 to 10 dtex.

16. Voluminous nonwoven composite comprising a first layer of melt-spun endless filaments, laid down in entangled manner, and a second layer of crimped staple fibers, wherein a) the endless filaments have a fineness of 0.8 to 1.8 dtex, b) the crimped staple fibers have a fineness of 2.2 to 15 dtex, and c) the layers are stabilized and intimately connected with one another exclusively via water jets, to form the voluminous nonwoven composite, and wherein the voluminous nonwoven composite has more than 5 pores per cm.sup.2 having a diameter of 0.2 mm.

17. Voluminous nonwoven composite comprising a first layer of melt-spun endless filaments, laid down in entangled manner, and a second layer of crimped staple fibers, wherein a) the endless filaments have a fineness of 0.8 to 1.8 dtex, b) the crimped staple fibers have a fineness of 2.2 to 15 dtex, and c) the layers are stabilized and intimately connected with one another exclusively via water jets, to form the voluminous nonwoven composite, and wherein at least some of the endless filaments and/or at least some of the staple fibers have a non-round cross-section and/or are hollow.

18. Voluminous nonwoven composite comprising a first layer of melt-spun endless filaments, laid down in entangled manner, and a second layer of crimped staple fibers, wherein a) the endless filaments have a fineness of 0.8 to 1.8 dtex, b) the crimped staple fibers have a fineness of 2.2 to 15 dtex, and c) the layers are stabilized and intimately connected with one another exclusively via water jets, to form the voluminous nonwoven composite, wherein the second layer contains not only the one crimped staple fibers but also, in addition, other crimped staple fibers having a fineness from 1.2 to 2.1 dtex, and wherein the second layer comprises a mixture of 20 to 99 wt.-% of the one staple fibers and 1 to 80 wt.-% of the other staple fibers.

19. Nonwoven composite according to claim 18, wherein the one crimped staple fibers comprise one material, and the other crimped staple fibers comprise a different material from the one crimped staple fibers.

20. Method for the production of a voluminous nonwoven composite, the method comprising steps of: laying down a first layer of melt-spun endless filaments in entangled manner, the melt-spun endless filaments having a fineness of 0.8 to 1.3 dtex, applying a second layer of crimped staple fibers to the first layer of the melt-spun endless filaments, the crimped staple fibers having a fineness of 2.2 to 15 dtex, and water-jet stabilizing the first layer and the second layer so that the crimped staple fibers are intimately connected to the melt-spun endless filaments.

21. Method according to claim 20, wherein the second layer contains not only the one crimped staple fibers but also, in addition, other crimped staple fibers having a fineness from 1.2 to 2.1 dtex, and wherein the second layer comprises a mixture of 20 to 99 wt.-% of the one staple fibers and 1 to 80 wt.-% of the other staple fibers.

22. Method according to claim 20, further comprising a step of embossing a relief during the water-jet stabilization, the relief having discrete raised locations.

23. Method according to claim 20, further comprising a step of: carrying out an additional embossing via a thermo-calender and/or an ultrasound calender, after the water-jet stabilization.

24. Method according to claim 20, further comprising a step of passing the endless filaments and/or the crimped staple fibers to the water-jet stabilization in an inline process.

25. Method according to claim 20, wherein the first layer and/or the second layer is pre-stabilized.

26. Method according to claim 20, further comprising a step of passing the first layer and/or the second layer to the water-jet stabilization in an offline process.

27. Method according to claim 25, wherein both the first layer and the second layer are pre-stabilized, are produced separately from one another, and are then passed to the water-jet stabilization.

28. Method according to claim 20, further comprising a step of passing at least one additional layer of endless filaments and/or staple fibers to the water-jet stabilization.

Description

(1) Further advantageous embodiments of the invention can also become evident from the exemplary embodiments described below, which are shown in the drawing. In the drawing, the figures show:

(2) FIG. 1 schematically, an inline production line for the production of a voluminous nonwoven composite according to the invention,

(3) FIG. 2 schematically, an offline production line for the production of a voluminous nonwoven composite according to the invention,

(4) FIG. 3 schematically, in a top view, the back side of a diaper having a voluminous nonwoven composite according to the invention,

(5) FIG. 4 schematically, in cross-section, a voluminous nonwoven composite according to the invention with an embossed relief,

(6) FIG. 5 schematically, in cross-section, a diaper having a voluminous nonwoven composite according to the invention,

(7) FIG. 6 schematically, in cross-section, a diaper having a voluminous nonwoven composite according to the invention,

(8) FIG. 7 microscopically, an 8 magnification of a voluminous nonwoven composite according to the invention, and

(9) FIG. 8 microscopically, an 8 magnification of a spun-bond nonwoven according to the state of the art.

(10) FIG. 1 schematically shows an inline production line 10 for the production of a voluminous nonwoven composite 12 according to the invention.

(11) At the start of the method for the production of the voluminous nonwoven composite 12, thermoplastic raw material is passed to the extruders 14, melted, and pressed through a nozzle plate 16. The hot filaments 18 are stretched with blowing air 20, cooled, and laid down onto the transport belt 22 as endless filaments 18.

(12) A layer 26 composed of carded staple fibers 28 is laid down onto this spun-bond nonwoven layer 24.

(13) For this purpose, staple fibers 28 in bale form 58 are transported to a card or carding device 30, using a bale opener 60. There, a uniform nonwoven layer 26 composed of staple fibers 28 is produced, which 26 is applied to the aforementioned spun-bond nonwoven layer 24 without compacting.

(14) In the subsequent water-jet stabilization or water-jet needling 32, the layers 24, 26 are intimately connected with one another, so that the two-layer structure is lost and an approximately homogeneous voluminous nonwoven or nonwoven composite 12 is formed.

(15) In the last step of water-jet needling or water-jet stabilization 32, an embossing can be introduced into the nonwoven composite 12, using a drum 34 provided with a relief.

(16) Subsequently, the nonwoven composite 12 is dried in a dryer 36 and wound into rolls using a winder 38.

(17) FIG. 2 schematically shows an offline production line 42 for the production of a voluminous nonwoven composite according to the invention.

(18) In this connection, a slightly pre-stabilized spun-bond nonwoven layer 24 is unrolled from a roll 40, without tension, and laid down onto a transport belt 22. A layer 26 composed of carded staple fibers 28 is laid down onto the spun-bond nonwoven layer.

(19) For this purpose, staple fibers 28 in bale form are transported to a card or carding device 30 using a bale opener. There, a uniform nonwoven or a uniform nonwoven layer 26 is produced, which 26 is laid down onto the slightly pre-stabilized spun-bond nonwoven layer 24 without compacting.

(20) In the subsequent water-jet stabilization or water-jet needling 32, the layers 24, 26 are intimately connected with one another, so that the two-layer structure is lost and an approximately homogeneous voluminous nonwoven or nonwoven composite 12 is formed.

(21) In the last step of water-jet needling or water-jet stabilization 32, an embossing can be introduced into the nonwoven composite 12, using a drum 34 with a relief.

(22) FIG. 3 shows a top view of the back side 44 of a diaper 46, to which the voluminous nonwoven composite 12 according to the invention is applied and serves as what is called the landing zone 48 of a hook-and-loop closure. Furthermore, the hook-and-loop tapes 50 that belong to the hook-and-loop closure and have hooks are shown.

(23) FIG. 4 shows a voluminous nonwoven composite 12 according to the invention, into which a relief 52 is embossed during water-jet stabilization 32. This mountain 54 and valley structure 56 allows the hooks of the hook-and-loop tape 50 of a hook-and-loop closure to hook into the voluminous nonwoven composite particularly well.

(24) FIG. 5 schematically shows, in cross-section, a diaper 46 having a cover nonwoven composite 58 or top-sheet spun-bond nonwoven and a voluminous nonwoven composite 12 according to the invention disposed underneath it, which functions as what is called an acquisition layer and lies on an absorbent body 62 of the diaper 46. The large-pore structure of the nonwoven composite 12 according to the invention allows rapid entry of liquid in this connection.

(25) FIG. 6, finally, schematically shows, in cross-section, a diaper 46 having a cover nonwoven 58 composed of a voluminous nonwoven composite 12 according to the invention, which fulfills the function of what is called a top sheet having an integrated acquisition layer. The advantage of such a use consists in that it is not necessary to use two separate nonwoven layers, as described in FIG. 5.

(26) In the following, a voluminous nonwoven composite SC40 according to the invention will be explained in comparison with a known spun-bond nonwoven S40.

(27) The nonwoven composite SC40 is produced using an inline methodcorresponding to FIG. 1and has a weight per surface area of 40 g/m.sup.2, comprising a first layer having a weight per surface area of 25 g/m, of melt-spun endless filaments laid down in entangled manner, composed of polypropylene, which have a fineness of 1.2 dtex, and a second layer having a weight per surface area of 15 g/m.sup.2, composed of a mixture of crimped staple fibers, wherein the mixture has 65 wt.-% crimped staple fibers composed of polyester, having a fineness of 1.7 dtex, and 35 wt.-% staple fibers composed of polypropylene, having a fineness of 6.6 dtex. The length of the staple fibers amounts to 4 cm. The layers are exclusively stabilized and intimately connected with one another by means of water jets, to form the voluminous nonwoven composite.

(28) The spun-bond nonwoven S40, which comprises only one layer having a weight per surface area of 40 g/m2, has melt-spun endless filaments laid down in entangled manner, composed of polypropylene, having a fineness of 1.2 dtex, wherein the layer is embossed by means of a thermo-calender.

(29) Because of the fact that the mixture of crimped staple fibers has 35 wt.-% crimped staple fibers having a fineness of 6.6 dtex, whereinas shown in FIG. 1no compacting takes place before water-jet needling, in advantageous manner, great thickness and a low density of the finished voluminous nonwoven composite is obtained.

(30) In Table 1, different mechanical properties of the voluminous nonwoven composite SC40 according to the invention and of the spun-bond nonwoven S40 are listed.

(31) TABLE-US-00001 TABLE 1 Technical Voluminous Spun-bond properties composite nonwoven Test method Weight per 40 40 WSP 130.1 (09) surface area [g/m.sup.2] Thickness [mm] 0.6 0.34 WSP 120.1 (09) Density [g/cm.sup.3] 0.07 0.12 mathematical Air 180 96 WSP70.1 (08) permeability [m.sup.3/m.sup.2/min] Largest pore 200 (=outside 63 Porosimeter from bubble of measurement point range of <200 m) measurement [m] Passage of bead 6.6 0 Screen test size 0.35 mm [% of amount weighed in] Number of pores 12 0 Microscopic >0.2 mm/cm.sup.2 Tear strength, 50 65 WSP 110.4 (09) transverse direction [N/5 cm] Elongation to 180 95 WSP 110.4 (09) tear, transverse direction [%] Elongation, 40 5 WSP 110.4 (09) transverse direction, at 10 N [%]

(32) The measurement values for thickness, density, pore size, the screen test, and air permeability show that the voluminous nonwoven composite SC40 according to the invention is clearly more open and more voluminous as compared with the spun-bond nonwoven S40, at the same weight per surface area.

(33) FIGS. 7 and 8 show two microscopic images, magnified 8, of the voluminous nonwoven composite SC40 and of the spun-bond nonwoven S40, to make the different porosities clear. The voluminous nonwoven composite SC40 according to FIG. 7 shows an obvious greater porosity in the form of the background showing through as black, than the spun-bond nonwoven S40 according to FIG. 8. The black ovals of the spun-bond nonwoven S40 shown in FIG. 8 are not pores but rather thermal embossing points 64.

(34) The mechanical properties of the voluminous nonwoven composite SC40 are also clearly different from those of the spun-bond nonwoven S40. Thus, the tear strength of the voluminous nonwoven composite SC40 is lower, and the elongation is significantly greater than that of the spun-bond nonwoven S40. However, this lack of dimensional stability is advantageous for the stated areas of use. As shown in FIG. 3, the voluminous nonwoven composite SC40 forms the counter-piece having loops, to the part of a hook-and-loop closure having hooks, in the case of a diaper, as what is called a landing zone. As shown in FIG. 5, the voluminous nonwoven composite SC40 is also used as what is called an acquisition layer (12) in a diaper, is therefore disposed between absorbent body 62 and cover nonwoven 58, and is therefore not subject to any mechanical stress.

(35) The voluminous nonwoven composite according to the invention therefore differs fundamentally from a spun-bond nonwoven, in terms of diverse technical properties, and accordingly also from those nonwoven composites composed of endless filaments and staple fibers that are supposed to have the same technical properties as a spun-bond nonwoven, among other things as the result of water-jet needling.

REFERENCE SYMBOL LIST

Is Part of the Specification

(36) 10 inline production line 12 nonwoven composite 14 extruder 16 nozzle plate or spinning bar with nozzle package 18 filaments or endless filaments 20 blowing air 22 transport belt 24 spun-bond layer 26 layer of staple fibers 28 28 staple fiber 30 card or carding device 32 water-jet stabilization or water-jet needling 34 drum with relief 36 dryer 38 winder 40 roller 42 offline production line 44 back side of a diaper 46 46 diaper 48 landing zone 50 hook-and-loop tape with hooks 52 relief 54 mountain structure 56 valley structure 58 bale form or fiber bale (pure-type or mixed) 60 bale opener or fiber bale opener (Blendomat) 62 absorbent body 64 embossing points