ABSORBING AND DISTRIBUTING LAYER FOR A LIQUID TO BE ABSORBED AND PRODUCTS PRODUCED THEREFROM

Abstract

The present invention relates to an absorbing and distributing layer for a liquid to be absorbed, to a sheet material at least including a corresponding absorbing and distributing layer, to a hygiene article at least including a corresponding absorbing and distributing layer, to a method for producing a corresponding sheet material, and to the use of the corresponding absorbing and distributing layer.

Claims

1. An absorbing and distributing layer for a liquid to be absorbed, comprising at least one non-woven consisting of trilobal fibers.

2. The absorbing and distributing layer according to claim 1, wherein said absorbing and distributing layer has a rewet as measured by the EDENA standard test WSP 80.10 (05) of from 0.01 g to 0.50 g, and/or the trilobal fibers of the absorbing and distributing layer comprise a polymer selected from the group consisting of a polyolefin, polyethylene terephthalate, polytrimethylene terephthalate, polylactides, and copolymers or mixtures thereof.

3. The absorbing and distributing layer according to claim 1, wherein said trilobal fibers have an arm thickness of 4 μm to 10 μm.

4. The absorbing and distributing layer according to claim 1, wherein a ratio of arm thickness to arm length is from 1:10 to 1:1.

5. The absorbing and distributing layer according to claim 1, wherein said absorbing and distributing layer comprises several embossing surfaces.

6. The absorbing and distributing layer according to claim 5, wherein each of the embossing surfaces has a surface area of from 0.5 mm.sup.2 to 5 mm.sup.2, and the absorbing and distributing layer has a cumulated surface area of the embossing surfaces of 3% to 35%, of the total surface area of the absorbing and distributing layer.

7. The absorbing and distributing layer according to claim 1, wherein said absorbing and distributing layer comprises two spunbond layers and one melt-blown layer, the melt-blown layer being provided between the two spunbond layers.

8. The absorbing and distributing layer according to claim 1, wherein said absorbing and distributing layer has a thickness of from 0.3 to 2.0 mm.

9. The absorbing and distributing layer according to claim 1, wherein said non-woven completely consists of trilobal fibers, and the absorbing and distributing layer has a lower rewet as compared to an absorbing and distributing layer produced under identical conditions, but whose non-woven completely consists of round fibers with the same titer as the trilobal fibers.

10. A sheet material comprising at least: an absorbing and distributing layer according to claim 1; and an absorption layer.

11. A hygiene article comprising an absorbing and distributing layer according to claim 1.

12. A process for producing a sheet material according to claim 10, comprising the following steps: providing an absorbing and distributing layer according to claim 1; followed by contacting it with an absorption layer.

13. A method of reducing or preventing rewet comprising using trilobal fibers in an absorbing and distributing layer for reducing or preventing rewet.

14. The absorbing and distributing layer according to claim 1, wherein said absorbing and distributing layer has a rewet as measured by the EDENA standard test WSP 80.10 (05) of from 0.05 g to 0.3 g, and the trilobal fibers of the absorbing and distributing layer comprise polypropylene or polyethylene, copolymers or mixtures thereof.

15. The absorbing and distributing layer according to claim 5, wherein each of the embossing surfaces has a surface area of from 2 mm.sup.2 to 4 mm.sup.2, and the absorbing and distributing layer has a cumulated surface area of the embossing surfaces of 10% to 25%, of the total surface area of the absorbing and distributing layer.

16. The absorbing and distributing layer according to claim 1, wherein said trilobal fibers have an arm thickness of 12 μm to 30 μm.

17. The absorbing and distributing layer according to claim 1, wherein said absorbing and distributing layer has a thickness of from from 0.4 to 0.6 mm.

Description

[0109] Further advantageous embodiments are shown in the following Figures. However, the respective features seen therefrom are not limited to individual Figures or embodiments. Rather, one or more features of the above description can be combined in addition to further embodiments.

[0110] Herein:

[0111] FIG. 1 shows a schematic representation of an absorbing and distributing layer;

[0112] FIG. 2 shows a schematic representation of an absorbing and distributing layer having a melt-blown layer and two spunbond layers;

[0113] FIG. 3a shows a schematic representation of an absorbing and distributing layer;

[0114] FIG. 3b shows a schematic representation of an absorbing and distributing layer under the action of a pressure;

[0115] FIG. 4 shows a schematic representation of a sheet material with an absorbing and distributing layer and an absorption layer;

[0116] FIG. 5 shows a schematic representation of a sheet material with an absorbing and distributing layer and an absorption layer under the action of water;

[0117] FIG. 6 shows optical micrographs of trilobal fibers;

[0118] FIG. 7 shows a schematic structure of a nozzle for producing trilobal fibers;

[0119] FIG. 8 shows a schematic structure of a nozzle for producing trilobal fibers;

[0120] FIG. 9 shows a graphical representation of the strike-through times (SST) determined in the Examples for Comparative Examples 2a and 2b and for Example 2;

[0121] FIG. 10 shows a graphical representation of the strike-through times (SST) determined in the Examples for Comparative Examples 1a and 1b and for Example 1;

[0122] FIG. 11 shows a graphical representation of the rewet values determined in the Examples for Comparative Examples 2a and 2b and for Example 2; and

[0123] FIG. 12 shows a graphical representation of the rewet values determined in the Examples for Comparative Examples 1a and 1b and for Example 1.

[0124] FIG. 1 schematically shows a part of an absorbing and distributing layer 1 as described above.

[0125] FIG. 2 schematically shows the structure of an absorbing and distributing layer 1 as described above, having a melt-blown layer 3 and two spunbond layers, wherein the melt-blown layer 3 is provided between the two spunbond layers 2, 2′. The whole assembly represents an absorbing and distributing layer 1 as described above.

[0126] FIG. 3a schematically represents an absorbing and distributing layer 1 as described above. FIG. 3b schematically represents an absorbing and distributing layer 1 as described above under the action of a pressure 4. The trilobal fibers of the absorbing and distributing layer 1 as described above are deformed and compressed under the action of pressure 4, forming a compact layer.

[0127] FIG. 4 schematically represents a sheet material 5 as described above comprising an absorbing and distributing layer 1 as described above, and an absorption layer 6.

[0128] The illustration in FIG. 5 schematically represents a sheet material 5 with an absorbing and distributing layer 1 and an absorption layer 6 under the action of a liquid, such as water, H.sub.2O. The water H.sub.2O is absorbed by the absorbing and distributing layer 1 and distributed in the absorbing and distributing layer 1, before it is subsequently transmitted to the absorption layer 6.

[0129] FIG. 6 shows optical micrographs of trilobal fibers of an absorbing and distributing layer 1.

[0130] FIG. 7 schematically shows an exemplary structure of a nozzle for producing trilobal fibers.

[0131] FIG. 8 schematically shows an exemplary structure of a nozzle for producing trilobal fibers.

[0132] FIG. 9 shows the strike-through times (SST) determined in the Examples for Comparative Examples 2a and 2b and for Example 2 in a bar diagram. The non-wovens (spunbond) have a mass per unit area of 15 g/cm.sup.2.

[0133] FIG. 10 shows the strike-through times (SST) determined in the Examples for Comparative Examples 1a and 1b and for Example 1 in a bar diagram. The non-wovens (spunbond) have a mass per unit area of 12 g/cm.sup.2.

[0134] FIG. 11 shows the rewet values determined in the Examples for Comparative Examples 2a and 2b and for Example 2 in a bar diagram. The non-wovens (spunbond) have a mass per unit area of 15 g/cm.sup.2.

[0135] FIG. 12 shows the rewet values determined in the Examples for Comparative Examples 1a and 1b and for Example 1 in a bar diagram. The non-wovens (spunbond) have a mass per unit area of 12 g/cm.sup.2.

Measuring Methods

[0136] All of the following determinations were performed at 23° C., 1013 mbar and 50% relative humidity, unless otherwise stated or appropriate. The samples were stored for 24 hours under laboratory conditions (23° C. and 50% relative humidity) before being measured.

Determination of the Filament Titer

[0137] The determination of the filament titer is effected by means of a microscope. The conversion of the measured titer (in micrometers) to decitex is performed according to the following formula (PP density=0.91 g/cm.sup.3):

[00001]${\left(\frac{\mathrm{Titer}.Math.\text{?}}{2}\right)}^2.Math.\pi .Math.\rho \left[\frac{g}{{\mathrm{cm}}^3}\right].Math.0.01=\mathrm{Titer}.Math.\text{?}\left[\frac{g}{{10}^4.Math..Math.m}\right]$$\text{?}.Math.\text{indicates text missing or illegible when filed}$

Determination of the Mass Per Unit Area

[0138] The determination of the mass per unit area is effected on test specimens having a size of 10×10 cm according to DIN EN 29073-1. The thickness of the non-woven material is measured as the distance of two plane-parallel measuring surfaces of a particular size, between which the non-woven materials are under a defined measuring pressure. The method is performed by analogy with DIN EN ISO 9073-2. Load: 125 g; measuring surface area: 25 cm.sup.2; measuring pressure: 5 g/cm.sup.2.

Determination of Air Permeability

[0139] The measurement of the air permeability is effected according to DIN EN ISO 9237. The surface area of the measuring head is 20 cm.sup.2, the test pressure applied is 200 Pa.

Determination of Strike-Through Time

[0140] The measurement of the strike-through times of the non-woven materials (“liquid strike-through time”) is effected according to the EDENA standard test: WSP 70.3 (05) (“Standard Test Method for Nonwoven Coverstock Liquid Strike-Through Time Using Simulated Urine”).

Rewet (or Wetback)

[0141] The measurement of the rewet of the non-woven materials (“liquid strike-through time”) is effected according to the EDENA standard test: WSP 80.10 (05) (“Standard Test Method for Nonwovens Coverstock Wetback”).

EXAMPLE 1

[0142] A non-woven material with a mass per unit area of 12 g/m.sup.2 and a titer of 2 dtex was prepared, wherein the fibers have a trilobal structure. The fibers were made of a commercially available Ziegler-Natta polypropylene. The add-on of the non-woven was subsequently adjusted to about 0.4% (determined by extraction with isopropanol; accuracy +/−0.03%). The rewet and the strike-through time of the non-woven prepared were subsequently determined.

EXAMPLE 2

[0143] By analogy with Example 1, a non-woven material with a mass per unit area of 15 g/m.sup.2 and a titer of 2 dtex was prepared, wherein the fibers have a trilobal structure. The fibers were made of a commercially available Ziegler-Natta polypropylene. The add-on of the non-woven was subsequently adjusted to about 0.4% (determined by extraction with isopropanol; accuracy +/−0.03%). The rewet and the strike-through time of the non-woven prepared were subsequently determined.

COMPARATIVE EXAMPLE 1a

[0144] By analogy with Example 1, a non-woven material with a mass per unit area of 12 g/m.sup.2 and a titer of 2 dtex was prepared, wherein the fibers have a round structure. The fibers were made of a commercially available Ziegler-Natta polypropylene. The add-on of the non-woven was subsequently adjusted to about 0.4% (determined by extraction with isopropanol; accuracy +/−0.03%). The rewet and the strike-through time of the non-woven prepared were subsequently determined.

COMPARATIVE EXAMPLE 1b

[0145] By analogy with Example 1, a non-woven material with a mass per unit area of 12 g/m.sup.2 and a titer of 2 dtex was prepared, wherein the fibers have a round structure. The fibers were made of a commercially available metallocene polypropylene. The add-on of the non-woven was subsequently adjusted to about 0.4% (determined by extraction with isopropanol; accuracy +/−0.03%). The rewet and the strike-through time of the non-woven prepared were subsequently determined.

COMPARATIVE EXAMPLE 2a

[0146] By analogy with Example 1, a non-woven material with a mass per unit area of 15 g/m.sup.2 and a titer of 2 dtex was prepared, wherein the fibers have a round structure. The fibers were made of a commercially available Ziegler-Natta polypropylene. The add-on of the non-woven was subsequently adjusted to about 0.4% (determined by extraction with isopropanol; accuracy +/−0.03%). The rewet and the strike-through time of the non-woven prepared were subsequently determined.

COMPARATIVE EXAMPLE 2b

[0147] By analogy with Example 1, a non-woven material with a mass per unit area of 15 g/m.sup.2 and a titer of 2 dtex was prepared, wherein the fibers have a round structure. The fibers were made of a commercially available metallocene polypropylene. The add-on of the non-woven was subsequently adjusted to about 0.4% (determined by extraction with isopropanol; accuracy +/−0.03%). The rewet and the strike-through time of the non-woven prepared were subsequently determined.

[0148] In the following, the determined values of rewet and of the strike-through time as well as the adjusted add-on values for the Examples and Comparative Examples are represented in tabular form:

TABLE-US-00001 Strike-through time [s] Rewet [g] Add-on Example 1 3.02 ± 0.13 0.20 ± 0.10 0.39% Example 2 4.04 ± 1.00 0.13 ± 0.03 0.39% Comparative Example 1a 3.09 ± 0.33 2.00 ± 0.93 0.42% Comparative Example 1b 3.53 ± 0.72 1.80 ± 0.44 0.46% Comparative Example 2a 3.01 ± 0.29 1.21 ± 0.26 0.42% Comparative Example 2b 3.57 ± 0.28 2.30 ± 0.99 0.46%

[0149] In Examples 1 and 2, it is clearly seen that the rewet is many times lower than that of Comparative Examples 1a to 2b. For illustration, the results have been graphically represented in FIGS. 9 to 12.