EP1448361A2

EP1448361A2 - Embossed non-woven fabric having a three-dimensional structure

Info

Publication number: EP1448361A2
Application number: EP02790397A
Authority: EP
Inventors: William A. Casey; Claudio Julian Balbin 2561 SUAREZ
Original assignee: Carl Freudenberg KG
Current assignee: Carl Freudenberg KG
Priority date: 2001-11-21
Filing date: 2002-11-18
Publication date: 2004-08-25
Anticipated expiration: 2022-11-18
Also published as: WO2003043806A2; ATE334813T1; WO2003043806A3; CA2468027A1; MXPA04004846A; RU2004119034A; KR20050044583A; RU2266823C2; US7678442B2; AU2002366221A1; BR0106472A; CA2468027C; EP1448361B1; CN1310746C; US20050008825A1; KR100592617B1; DE50207743D1; AU2002366221A8; CN1589199A; JP2005509758A

Abstract

The invention relates to a three-dimensionally embossed non-woven fabric, which is comprised of fibers and/or filaments (3) oriented primarily in the moving direction (2) of the machine, and has zones (5, 7) with regularly alternating elevations (4a, 8a) and indentations (4b, 8b), which are separated from one another by non-embossed areas (6) that are continuous in the moving direction (2) of the machine. These non-embossed areas constitute a proportion ranging from 5 % to 50 % with regard to the entire surface of the non-woven fabric (1) and the elevations (4a, 8a) and indentations (4b, 8b), when viewed from the opposite side, form indentations or elevations respectively, whereby the surfaces (10a, 10b) delimited by the elevations give the non-woven fabric an apparent thickness ranging from 0.5 mm to 5.5 mm.

Description

Embossed nonwoven fabric with a three-dimensional structure

The invention relates to an embossed, open-pore nonwoven fabric with a three-dimensional structure, a method for its production and a device used in the process. The nonwoven fabric consists of regularly alternating areas with deep-drawn, weight-thinned 3D surveys and non-deep-drawn, flat and unchanged zones.

The invention also relates to a special embossing process and the roll geometry required for this, in order to impart the special 3D embossing structure to the nonwoven fabric after passing through the press nip of two interlocking positive and negative rolls.

The absorbent core of children's diapers, incontinence and feminine hygiene products is on the wearing side today, i.e. the body-facing side is covered by at least two layers. Between the cover nonwoven or the perforated film and the absorbent core there is a receiving and distribution layer (AVS) made of nonwoven or reticulated foam, which, as the name already expresses, absorbs the body fluid (urine, thin stool or menses) quickly and as evenly as possible the underlying core, usually made of pulp and superabsorbent powder. On the one hand, this keeps the human skin dry with the result of preventing skin irritation, and on the other hand prevents leakage of the body fluid through side leakage. On the back, the absorbent hygiene product is countered with a waterproof film or a nonwoven film laminate

Body fluid passage sealed.

For AVS, nonwovens bonded thermally in hot air flow dryers or nonwovens bonded with polymer dispersions made of crimped, relatively coarse-titer fibers are known. The fibers have a titer of more than 3.3 dtex and exist preferably on polyester (polyethylene terephthalate) and / or polyolefins, bicomponent fibers with side-by-side or core / jacket structure being used for the purpose of fiber bonding in the through-flow furnace and one of the two fiber components melting significantly more deeply than the other component. Such nonwovens have a relatively high volume (thickness) in relation to their low weight immediately after they have been manufactured. However, it is known that this initial thickness is already significantly reduced when the goods are rolled up under the usual stresses and the pressing conditions in the packaging make a further contribution to the reduction in thickness.

For this reason, solutions were sought not only to achieve a thickness by means of more or less statistically distributed crimped fibers and their binding, but rather such crimped nonwoven fabrics by means of corrugation or other geometric orientations into the third dimension, which we will always describe in the future with the Z direction, bring to. It has been shown that higher compression resistances can be achieved than with so-called high-loft nonwovens, with the consequence of a significantly lower loss of thickness when passing through the manufacturing stages of a diaper, including packaging and storage.

DE 197 25 749 A1 describes an embossing process for producing a structured, voluminous nonwoven. Here, a pre-consolidated spunbonded nonwoven whose continuous filaments have only been stretched 50 to 70% of the maximum possible stretch is subjected to a special post-processing. This consists of a passage of the spunbonded nonwoven fabric between a positive roller with a knob surface and a negative roller with lamellar webs transverse to the machine direction, the lamellas engaging in the alleys kept clear of the knob. This creates 3D nonwovens with areas of cone-like, weight-thinned elevations, which are surrounded by linear, undeformed areas.

The disadvantage of the embossing process described in DE 197 25 749 A1 is that it is limited to undrawn or partially stretched continuous filament nonwovens (spunbonded nonwovens). Such nonwovens consist of coarse-tufted, uncrimped continuous fibers, which are known to be hard, rough and non-textile products lead and are therefore not used as AVS in diapers. Even continuous filaments with side-by-side structure or asymmetrical core / sheath structure do not cause any crimp in the partially stretched state. This is usually only triggered by a thermal aftertreatment which, in turn, as known to the person skilled in the art, prevents stretchability (or deformability) by the crystallization that has occurred. And thus the requirements for the applicability of the embossing method described in DE 197 25749 A1 are missing.

EP-B 0.809.991 and EP-A 0.810.078 describe a fluid distribution material with improved fluid properties. Here a plastically deformable web is deformed into a nonwoven fabric with an SD structure by passing through a pair of negative / positive rollers. A variety of the two above The embossed material and process for this purpose are those which are described in EP-B 0.499.942. However, such a structure similar to corrugated cardboard has the disadvantage that it does not withstand permanent pressure stresses.

In EP applications 1,047,824, 1,047,823, 1,047,822 and 1,047,821, nonwovens are produced in an intermediate stage with elevations and depressions in that the fabric passes through two heated gear rollers. The ribs are not compression stable due to the fact that you lack a non-stabilizing flat surface that is glued to one side of the elevations or stiffeners. Rather, the patent applications mentioned relate to pulling out the corrugations as far as possible or in part in order to thereby produce soft and slightly elastic products transverse to the corrugation.

Disposable absorbent articles with a faeces management layer are known from EP-A 0.976.375, EP-A 0.976.374 and EP-A 0.976.373, the latter consisting of a corrugated nonwoven fabric which is placed on a flat nonwoven fabric carrier (EP-A 0.976. 375) is glued on. Instead of the nonwoven backing, thick polymer filaments (EP-A 0.976.374) or nets (EP-A 0.976.37) can also be used. Such corrugated and stabilized nonwoven laminates have proven to be suitable AVS for faecal management and improved urine management. However, the manufacture of such SD laminate structures is very complex and requires two components and in some cases an additional glue. However, the use of a thick monofilament (with a titer in the range of a few thousand dtex) turned out to be unsuitable, since such monofilaments are undrawn (or come from the perforated nozzle) and are therefore diluted with the strong mechanical stress in the machine direction during diaper production stretch the filament, i.e. have an unacceptable property in this regard.

It is the object of the present invention to remedy the disadvantages of the prior art described above and to show an embossed nonwoven which, without the need for an additional stabilizing layer after a previous compression, returns better to its original shape than the previously known designs and which therefore better suited for the absorption of liquids of different compositions or the transport of liquids in a suction layer. The invention is also based on the object of specifying a method for producing a nonwoven fabric and a device suitable for carrying out the method. In particular, the diaper manufacturer is to be offered an embossing device as an additive for a diaper production line, which allows him to convert an unembossed, two-dimensional nonwoven fabric in-line with the diaper production into the shape of an embossed, three-dimensional nonwoven fabric with improved liquid absorption and distribution function and in a diaper or to place a wound dressing. In addition, the nonwoven fabric should also be able to be produced independently of the diaper production and should largely have the same properties after an intermediate storage in the rolled-up state.

According to the invention, the three-dimensionally embossed nonwoven consists of fibers and / or filaments 3 and zones 5, 7 oriented mainly in the machine direction 2, with regularly alternating elevations 4a, 8a and depressions 4b, 8b, which are characterized by continuous areas 6, which are unembossed in the machine direction 2, from one another are separated, which make up a share of 5% to 50% based on the total area of the nonwoven fabric 1 and in which the elevations 4a, 8a and depressions 4b, 8b form depressions or elevations, viewed from the opposite side, the elevations limited areas give the nonwoven fabric 1 an apparent thickness in the range of 0.5 mm to 5.5 mm. Further advantageous refinements are set out in the subclaims.

The invention describes a nonwoven fabric made of staple fibers, in which partial surface areas in the machine running direction have alternating elevations and depressions (peaks / valleys) and each row of elevations is interrupted by a non-deformed linear area. The non-deformed linear regions are arranged in the 3-dimensionally deformed nonwoven fabric symmetrically to asymmetrically to the ridges and valleys of the respectively adjacent regions. In a preferred embodiment, the regions deformed into heights and valleys extend symmetrically along the non-deformed linear region.

The row of the next deforming areas transverse to the machine direction are arranged in the machine direction in such a way that they are each in a gap with the adjacent shaft row.

The corrugations extend exactly in the machine direction.

The method according to the invention for producing a nonwoven fabric is carried out in such a way that fibers and / or filaments 3 are laid down in a machine-oriented manner mainly in the machine direction 2 to form a pile, and are formed into a three-dimensional nonwoven fabric by treatment with embossing rollers at temperatures from 65 ° C. to 160 ° C. become.

Further advantageous refinements of the method are set out in the subclaims.

The staple fibers of the 2-dimensional nonwoven for 3D embossing are used in

Machine direction stored. The fibrous web can additionally along this

Preferred direction have been reoriented by an upsetting device.

The staple fibers of the staple fiber pile deposited in the machine direction are crimped in two and / or three dimensions. The fibers consist of such fiber polymers, which result in a high restoring force against mechanical forces. Polyethylene terephthalate fibers with a titer of 3.3 to 30 dtex, but preferably 6.7 to 18 dtex, have proven particularly suitable. Fiber ^'different titers may be blended with each other.

The staple fiber webs are bound either adhesively by using aqueous polymer dispersions by known processes, by thermal fiber / fiber bonding in a forced air oven or by application of heat and pressure in a pair of calenders. In the case of a convection oven passage, bicomponent fibers are added to the homophilic fibers as binding fibers.

The nonwoven fabric presented for embossing contains a hydrophilic, well-wetting surface-active agent (surfactant) that has either already been applied in or on the fiber by the fiber manufacturer and / or has been subsequently applied to the nonwoven fabric and / or by the polymer dispersion preparation used in the Nonwoven has been registered. The surfactant can have a different degree of adhesion to the fibers and thus be washable or semi-permanent up to being completely permanent against contact with body fluids.

In the case of an adhesive bond, an aqueous polymer dispersion based on a butadiene copolymer, e.g. Styrene-butadiene or acrylonitrile-butadiene copolymer used. The binder is preferably free of crosslinking components and remains in the nonwoven in a thermoplastic deformable state after application. The Shore A hardness of the binder film cast from the dispersion is in the range from approximately 70-100, preferably 75-95.

The cross section of the staple fibers can have different shapes, such as round, oval, trilobal, square, rectangular. The fiber polymer can be distributed in the same density over the entire fiber cross section. However, the fiber can also be hollow on the inside, the cavity being able to make up 10-30% of the total volume of the fiber. All crimped one-component synthetic fibers are suitable for the embossing process according to the invention, which do not shrink or even melt under the embossing conditions. The crimped synthetic fibers can also be blended with undrawn, uncrimped fibers, but with a proportion <50%.

The base material to be deformed into a 3D structure preferably contains polyester fibers if the nonwoven is bonded with an aqueous dispersion. The fiber: binder ratio is approximately 20:80 to 40:60. The binder can have been applied using known application methods, such as foam impregnation, one-sided slapping or wet-on-wet printing. The binder can be evenly distributed over the cross-section of the nonwoven or have a binder application quantity gradient from one side to the other side. The drying temperatures and residence times in the dryer must be selected so that the polymer is completely filmed. This can be seen from the transparency (of the unpigmented binder) of the binder points.

The staple fiber pile of the precursor can consist of one or up to three layers. The three layers preferably have an increasing average titer from one layer to the next adjacent layer. After the 3D deformation, the multi-layer nonwoven fabric with the coarsest (higher titer) pile side facing the underside of the covering nonwoven fabric is positioned in the diaper as an AVS. In the case of embossed nonwoven fabric with binder distribution gradients, the binder-rich side is in contact with the absorbent core or the hydro-melt meltblown nonwoven or tissue paper (English gore wrap) enveloping it.

The device according to the invention for carrying out the method consists of at least two embossing rollers 21, 22 which are in engagement with one another in such a way that a nonwoven fabric 20 is guided and shaped between them, the embossing rollers 21, 22 consisting of gear wheels 11 which are separated by spacers 12 are arranged on a shaft 13.

Further advantageous embodiments of the device are set out in the subclaims. The invention is explained in more detail with reference to 6 figures.

Show it:

Figure 1 - the top view of a three-dimensionally shaped nonwoven according to the invention

Figure 2 - the cross section of a three-dimensionally shaped nonwoven according to the invention along the section line 9 - 9

Figure 3 - the cross section of a three-dimensionally shaped nonwoven according to the invention along the section line 27-27

Figure 4 - schematic representation of an embossing roller

Figure 5 - the cross section through an embossing roller

Figure 6 - schematic representation of a device according to the invention

Figure 7 - Cross section of a gear wheel

The 3D embossed nonwoven fabric 1 is shown in the top view in Fig. 1. 2 indicates the machine direction. The nonwoven fabric consists of the fibers 3 oriented in the machine direction 2, which are bound to one another by known methods. In the machine direction 2, the nonwoven fabric 1 has two continuously repeating zones 5, 7 and the area 6, the zones 5 and 7 being 3D embossed and the area 6 positioned between zones 5 and 7 remaining in the unembossed state. The elevations 4a of the zones 5 alternate with depressions (valley depressions) 4b. The elevations 8a and depressions 8b are arranged within the zones 7 such that they are, for example, at a gap with respect to the elevations 4a and depressions 4b of the zones 5. The nonwoven fabric 1 thus consists of two surfaces, the elevations forming one surface and the depressions forming the other surface. In

Fig. 2 shows a section along the line AA and the view from this section in the cross-machine direction 2. In the foreground is the wavy 3D structure, which is shown by stringing together the arcuate elevations 4a and depressions 4b. The unembossed areas 6 extend behind these corrugations in the foreground in the machine direction 2. Behind the areas 6 there extends a second wavy line, which is characterized by the elevations 8a and valleys 8b ^' . 8a and 8b each stand on the gap to 4a and 4b.

In Fig. 3 the sectional view along the line B - B (ie across the machine direction 2) is shown as the foreground and the view in the machine direction 2 as the background (dashed lines). The weight per unit area of the non-deep-drawn areas 6 is significantly higher than the weight of the adjacent zones 5 and 7. The weight per unit area of the 3D-embossed zones 5 and 7 is reduced by the factor resulting from the division of the distance 28 from the circumference of position 29 Digit 30 results. For example, if the basis weight of the non-embossed nonwoven is 60 g / m ² , the distance 28 is 6 mm in length and the circumference from position 29 to 30 is 15 mm in length, the 3D-embossed zones have a weight of 24 along their surfaces g / m ² , which corresponds to a significant thinning of the material within the embossed zones by 60% fiber mass. The higher basis weight in zones 6 in connection with the undamaged fiber bonds causes the advantageous property of the nonwoven that, overall, without the need for an additional stabilizing layer, it returns better to its original shape after a previous compression than all previously known designs with the result that the nonwoven is more suitable for absorbing liquids of different compositions or for transporting the liquids into a suction layer.

An embossing roller 21 is shown in Fig. 4. On a shaft 13, which is provided with a clamping wedge 14, a toothed wheel washer 11, then an unserrated spacer washer 12 with a smaller diameter are placed alternately. The diameter of the disc 12 corresponds to the diameter of the gear disc 11 at its lowest points 17 (the valleys).

Fig. 5 shows a cross section of such an embossing roller 21. The teeth 15 of the front toothed wheel disk 11 have the elevations 16 and depressions 17. Behind the toothed wheel disk 11, an unserrated disk 12 with the diameter 19 is placed on the axle 13 with its groove 18 (not visible).

According to Fig. 6, an embossing unit consists of at least two intermeshing embossing rollers 21 and 22. At least one of the two can be heated. A heat source 26 can also be attached to heat the roller surface. In the region 23, the non-embossed nonwoven web 20 passes the interlocking teeth of the two embossing rollers 21 and 22 and is deformed, favored by heat, to form a 3D-embossed nonwoven with the new surface structure. The take-off roller 24 has a rough surface 25, which favors the further transport of the flat goods.

The embossing device can be used in a max. Width up to approx. 220 cm can be operated. In a narrower embodiment in roller widths between approximately 55 to 125, preferably between 65 and 90 cm, it can be integrated in diaper machines. This is a special embodiment of the method, which has the advantage of delivering flat roll goods, cut into slices and avoiding the logistical problem of storing the tapes in boxes (fastooning) or cost-intensive, cross-shaped winding (spooling).

The method according to the invention with the special design of an embossing in the diaper machine has the further advantage that the non-embossed nonwoven fabric with fluid absorption and distribution function can be compressed more than one that is not subjected to 3D embossing. A non-embossed roll product is always fraught with the problem that a greater thickness compression takes place in the roll core near the sleeve than in the outside area, which does not completely equalize even after being placed in the diaper. A master roll with a 3 inch core as the inside diameter, wrapped with binder-bound absorbent and distribution nonwoven on an outside diameter of 114 cm results in approx. 2,500 to 3,000 running meters per roll. By a lesser Although the winding hardness could largely solve the compression problem in the winding core, it is associated with the cost disadvantage of having fewer running meters on the roll. The method according to the present invention or the resulting embossed, voluminous finished material permits a significantly stronger compression of the unembossed semi-material with the advantage of eliminating the compression problem mentioned on the winding core and the logistical advantage of significantly more running meters (running meters) length on the winding to get.

The non-embossed nonwoven in the weight range from 30 to 100 g / m ² , preferably 40 to 80 g / m ² has a thickness, measured at 0.5 kPA load, of 0.20 to 1.50 mm, preferably 0.35 to 1, 20 mm on. The thickness after the embossing depends primarily on the height of the teeth, the distance between the teeth (degree of engagement = intensity of intermeshing) and secondly on the weight per unit area of the non-embossed nonwoven. The thickness of the embossed nonwoven measured over the areas conceived by the elevations is in the range from approximately 0.50 to approximately 5.50 mm, preferably approximately 0.900 to approximately 4.50 mm.

The width of zones 5 and 7 with gear embossing is in the range from approximately 3.0 to approximately 20 mm, preferably 6 to 12 mm. Zones 5 and 7 can each have the same width or else different widths. They are preferably of the same width. The area 6 is generally <half the sum of the width of the zone 5 and zone 7 and is preferably only about 5% to about 25% of this sum. If, for example, a width of 7.0 mm is selected for zones 5 and 7, the width of the areas 6 is only 0.7 mm to 3.5 mm. The areas 6 may have different widths, but may have a total area share of max. Do not exceed 50% and are preferably in the range from about 10 to about 33% based on the total area of the embossed nonwoven. However, 3D optics with regions 6 of equal width are particularly preferred.

On the underside of the 3D-embossed nonwoven fabric that can be used as AVS, hydrophilic (or designed to be absorbent by adding wetting agents) binder may have been subsequently applied. This side is understood to be the underside, the surface of which is delimited by the unembossed areas 6 and the depressions 4b and 8b becomes. Such a one-sided binder application can be advantageous for the purpose of further 3D structure stabilization and can promote the transport of the fluid in the direction of the absorbent core through increased hydrophilicity.

example 1

A pile of crimped polyester staple fibers with a titer of 6.7 dtex and a cutting length of 51 mm is laid down in the machine direction. The pile weight is 45 g / m ² . The pile is wetted with water in order to facilitate the subsequent printing on one side with binder. An aqueous polymer dispersion based on carboxylated copolymer styrene-butadiene is used as the binder. The Shore A hardness of the film produced from this binder is approximately 90 to 95. The 50% dispersion is added with wetting agent, some pigment and dilution water, so that a "water-thin" 40% mixture results. This mixture is applied to one side of the fiber web with the aid of an anilox roller, the depressions of which are filled with this mixture. During drying at 180 ° C on drying cylinders, some of the binder migrates in the direction of the binder-free side. This creates a concentration gradient of the binder from one side of the nonwoven to the other. After drying, the goods remain on the dryer until a complete filming of the binding points has taken place. The application amount of this relatively hard carboxylated styrene-butadiene latex is 15 g / m ² . This results in a fiber: binder ratio of 75:25.

The properties (thickness, repetition and the like) of this non-embossed goods are compared in Table 1 with those of an embossed goods.

This semi-finished material was then subjected to the embossing according to the invention, an embossing device according to FIGS. 4 to 6 being used.

Fig. 7 shows an enlarged cross section of a gear wheel. We understand n as the inner radius of the gear and r _{a as} the outer radius of the Gear. The height h of the teeth is calculated from the difference between r _a and n. The (curved) distance tj on the inside and t _a on the outside can be calculated from the formula for the circumference u = 2 r π. The extent u _a and uj can be calculated by multiplying the number of teeth z on the gear by the pitch tj and t _a :

In Examples 1, 2, embossing rollers with gear wheels of the following dimensions and shape were used:

Z = 28 n = 35 mm r _a = 37.5 mm

With the above mathematical relationships, the following values for tj and t _{a are} calculated: tj = 7.85 mm and t _a = 8.41 mm

Due to the tapering of the teeth towards the outside of the roller and the circular diameter of the roller _, the relationship applies to the distances dj and d _a

In Example 1, the ratio of d _a : dj is 2.88: 1.0.

The width of the spacer 12 (see Fig. 4) is 0.20 mm and the width of the gearwheels is 0.75 mm, which results in a portion of the non-embossed area 6 of approximately 20% of the total area of the nonwoven fabric.

The 60 g / m ² heavy nonwoven fabric 20 is passed through the nip of the two intermeshing embossing rollers 21 and 22 at a speed of 10 m / min (600 m / h). The outside temperature of the gear roller 11 made of steel SAE 1045 is 125 ° C. The gear roller 22 made of polyamide is unheated and heats up slightly when running. On Falling of the temperature on the steel roller is ensured by the additional heat source 26. The take-off roller 24 is cooled. The goods are then rolled up with the lowest possible tension.

Example 2

The procedure is as in Example 1, but with the difference that the pile weight has been reduced to 31 g / m ² . The proportion of binder was 12 g / m ² , which corresponds to a fiber: binder ratio of approximately 73:27.

The 3D embossing was carried out in accordance with Example 1.

Comparative Example 1

The 60 g / m ² binder-bonded nonwoven fabric produced in Example 1 is subjected to embossing according to the prior art. For this purpose, a pair of rollers has been produced in which no spacer disks 12 have been placed on the cone between the gear disks and in which the gear disks all have the same position, ie have not been rotated to a gap. The tooth depth is the same as in example 1.

The binder-bound, 60 g / m ² heavy nonwoven semi-material produced in Example 1 was embossed under the conditions of Example 1.

This conventionally embossed reference pattern with a kind of corrugation, which roughly corresponds to corrugated cardboard, was tested for thickness, repeatability and creep resistance. The results of the reference sample, the unembossed semi-material and the sample on Example 1 were compared in Table 1.

Test methods applied

• Liquid strike through time according to EβANA 150.3-96 (Lister tester) • Coverstock Rewet (also called Wet Back) according to EDANA 151.1 -96

Strike through time was measured after the 1st, 2nd and 3rd fluid exposure and the rewet after the 3rd fluid exposure.

Tab. 1 shows the results of Examples 1 and 2 of the non-embossed and embossed binder-bonded nonwoven as arithmetic mean values from 3 individual measurements.

Tab. 1: Liquid Strike Through and Rewet measured directly on the test piece (outside the diaper) according to the EDANA method with the Lister test arrangement

The results in Table 1 make it clear that in particular the liquid strike through time of the nonwoven embossed according to the invention is significantly lower (better) than in the unembossed state. Improvements can also be seen in the Rewet, but they are less significant than in the Liquid Strike Through Time. In contrast, in the Kanga test, carried out on a diaper (see Table 2), the Rewet results are even more significantly improved than in the EDANA Lister test.

Liquid Strike Through Time (soaking time) with the so-called Kanga test by Stockhausen S.OSSE.204-3.0 measured on a diaper: A commercially available diaper of the maxi plus size without an absorption and distribution layer was opened and placed between the absorbent core and the top layer of the test piece as an absorption and distribution layer. Then the diaper was closed again and subjected to the kanga test in this way. 120 ml of a 0.90% saline solution (so-called synthetic urine) were used as test liquid per sample. After the diaper is placed in the center between the round (corresponding to the body shape) shaped plastic body and the fabric belt wrapping around it, the plastic body is loaded with a weight of 12.5 kg. Then 120 ml of the liquid are poured into the vertically aligned (for girl, unisex) cylinder of the test apparatus and the time until the liquid is completely absorbed into the diaper is stopped.

After waiting for 20 minutes each, a second (infiltration time 2) and a third measurement (infiltration time 3) are carried out with the same amount of liquid (120 ml).

Rewet (rewetting with the so-called Kanga test from Stockhausen S.OSSE.204-3.0 measured on a diaper:

To determine the Rewet behavior, wait a further 20 minutes after the third liquid has completely soaked in, remove the diaper from the measuring apparatus and spread it out on a table. A weighed stack of 3 filter papers of approx. 40 g / m ² each is placed on the liquid entry point of the diaper and with 1270 g (which corresponds to a pressure load of approx. 20 g / cm ² ). After 20 minutes, the filter paper stacks are weighed out. The lower the value, the drier the baby's skin stays.

Tab. 2: Results of the soak time (strike through time) and the rewet determined according to the so-called Kanga method

Table 2 shows that the nonwoven fabric according to the invention, incorporated into a diaper, has significantly better properties than AVS.

• Creep resistance KB

To determine the creep resistance KB, samples of the format of approx. 7 x 7 cm were punched out and air-conditioned in the laboratory for 25 hours. 3 individual measurements were carried out to determine an arithmetic mean.

The test specimen was exposed to 7.2 kPa at 45 ° C for 72 hours. The area to be charged has been marked. The sample was then removed from the oven and relieved for 2 minutes. Then the thickness measured with a pressure of 0.5 kPa and a pressure area of 25 cm ² . After a discharge time of 2 hours and 24 hours, the thickness was measured again.

Table 3: Thickness measurement after thermal storage (creep resistance KB) and after different stress-free recovery times The initial thickness of the reference sample with conventional embossing (corrugation) shows a significantly lower thickness than example 1, 3D-embossed according to the inventive method, even after a load of 0.5 kPa.

• Specific volume (SV)

The thicknesses d were measured at loads of 0.50 kPa and 6.2 kPa. The following conversion gives the value for the specific volume in cm ³ / g (the reciprocal of the specific density):

SV = (d / FG) x 1000 in (cm ³ / g)

Where FG is the basis weight of the nonwoven in g / m ² and d is the thickness in mm.

Table 4: Specific volume

The values for the specific volume listed in Table 4 also show that a better nonwoven fabric with a significant fluid absorption function has been created with the 3D embossing according to the invention.

Claims

claims

1. Three-dimensional embossed fabric made of nonwoven fabric, characterized in that the nonwoven fabric (1) consists of fibers and / or filaments (3) and on both sides zones (5,7) with regularly or irregularly alternating elevations (4a, 8a) and depressions ( 4b, 8b) is provided, which are separated from one another transversely to the machine direction (2) by non-embossed, continuously formed areas (6) which extend in the machine direction and a proportion of 5% to 50%, based on the surface of the non-embossed nonwoven material s (1), where the elevations (4a, 8a) and depressions (4b, 8b), viewed from the opposite side, form depressions or elevations, and that the elevations on both sides are raised in relation to surfaces 28 , which are each formed by an imaginary extension of the two-sided surfaces of the unembossed, continuously formed areas (6).

2. The flat structure according to claim 1, characterized in that the apexes of the elevations on both sides (4a, 8a) largely touch imaginary planes 27 which have a distance H of 0.5 mm to 5.5 mm from one another.

3. The flat structure according to claim 1, characterized in that the apexes of the elevations on both sides (4a, 8a) largely touch imaginary planes 27 which are at a distance of 0.9 mm to 4.5 mm from one another.

4. Flat structure according to one of claims 1 to 3, characterized in that the areas (6) occupy a share of 10% to 33%, based on the total area of the nonwoven fabric (1).

5. Flat structure according to one of claims 1 to 4, characterized in that the fibers or filaments are mainly oriented in the running direction (2) of the system used in its manufacture.

6. Flat structure according to one of claims 1 to 5, characterized in that the elevations (4a, 8a) and depressions (4b, 8b) of adjacent zones (5, 7) are arranged in a grid-like pattern.

7. Flat structure according to one of claims 1 to 5, characterized in that the elevations (4a, 8a) and depressions (4b, 8b) of adjacent zones (5, 7) are arranged such that the elevations (4a) and depressions (8b )) are arranged symmetrically on both sides of the continuously formed areas, viewed in the direction of travel (2) of the system used in its manufacture.

8. Flat structure according to one of claims 1 to 5, characterized in that the elevations (4a, 8a) and depressions (4b, 8b) of adjacent zones (5, 7) on both sides of the continuously formed areas (6), in the running direction (2) the system used in its manufacture, are allocated to each other on a gap.

9. Flat structure according to one of claims 1 to 5, characterized in that the elevations (4a, 8a) and depressions (4b, 8b) of adjacent zones (5, 7) on both sides of the continuously formed areas (6), in the running direction (2) considered the system used in its manufacture, are arranged asymmetrically offset from each other.

10. A method for producing a flat structure according to one of claims 1 to 9, characterized in that a flat fleece is formed from fibers and / or filaments (3), mainly in the running direction (2) of the system (2) used in its manufacture. are oriented that the fibers and / or filaments (3) of the nonwoven are connected to one another and that the nonwoven thus obtained is subsequently exposed to the action of at least one embossing roller at a temperature of 65 ° C. to 160 ° C. and thereby in the form of a three-dimensional one Nonwoven is transferred.

11. The method according to claim 10, characterized in that the fibers or filaments are connected by a binder.

12. The method according to claim 11, characterized in that the binder is applied to one side of the nonwoven.

13. The method according to claim 11 or 12, characterized in that a wetting agent is added to the binder.

14. The method according to any one of claims 10 to 13, characterized in that only the continuously formed areas (6) are reinforced before, during or after the deformation by at least one second application of binder.

15. The method according to claim 14, characterized in that the second binder is applied by spraying or printing onto the continuously formed areas (6).

16. The method according to any one of claims 14 to 15, characterized in that a second application of binder is applied to the continuously formed areas (6) from both sides.

17. Device for carrying out the method according to one of claims 10 to 16, characterized in that at least two embossing rollers (21, 22) are provided in engagement with one another in such a way that a nonwoven fabric (20) can be passed and deformed between them, wherein the embossing rollers (21, 22) consist of gear wheels (11) which are arranged on a shaft (13) separated from one another by spacers (12).

18. The apparatus according to claim 17, characterized in that the gears (11) are straight or helical teeth.

19. The apparatus of claim 17 or 18, characterized in that the gears (11) of the embossing rollers (21, 22) are selected from the same or different materials and consist of iron, copper, aluminum and their alloys or polymers.

20. The apparatus of claim 17 or 18, characterized in that the gears (11) of the embossing rollers (21) made of aluminum and that of the embossing rollers (22) made of polyamide.

2 I.Device according to one of claims 17 to 20, characterized in that only one embossing roller is heated.

22. Device according to one of claims 17 to 21, characterized in that a heat radiator (26) is provided for heating.