NO320140B1 - Perforated floral fabric and its preparation as well as its use. - Google Patents

Description

The present invention provides perforated fluorescent substances, a method for their production and the use of the perforated fluorescent substances.

Hygiene products that absorb body fluids, such as children's nappies, adult nappies and sanitary napkins, are basically made up of an absorbent core, a sealing back side of a foil or a fleece/foil laminate and a body-facing, permeable surface element of thin, wear-resistant, soft fleece fabrics or a vacuum perforated foil with funnel-shaped, i.e. three-dimensional, openings. This vacuum-perforated foil surrounds the absorbent core whereby the largest perforation opening is directed outwards, that is, facing the body. The foil material is made up of hydrophobic thermoplastic polymer such as polyethylene, polypropylene or a copolymer of ethylene and polyvinyl acetate (EVA). This ensures that the foil surface on the one hand is not wetted by the body fluids, that the body fluids are only guided in the direction of the absorber core and that the inwardly tapering perforations prevent the body fluids from flowing backwards due to load, movement or pressure. As is known, the absorbent core usually contains, next to predominantly cellulose, also superabsorbent particles, SAP. Superabsorber polymers are distinguished by the fact that they can absorb aqueous liquids in large quantities and thereby form a gel body with more or less low gel strength during a clear increase in volume. The presence of SAP has the advantage that weight can be saved and the thickness of the absorber core can thereby be reduced and that the liquid cannot be released again during pressure loading so that leaks can thereby be largely prevented. However, SAP also has the shortcoming that it leads to known gel blocking and this to a greater extent the higher the proportion. By gel blocking is meant the effect that the liquid can no longer be transported further or can only be transported further very slowly. With suitable constructions of the absorbent hygiene products, however, this problem could also be solved. In this case, bulk pile fabrics or other very open structures that do not block when in contact with liquid are positioned between the absorber core and the cover layer. This intermediate layer absorbs liquid immediately, that is, it spontaneously removes it from the nappy surface and distributes it evenly. Fluid management is improved by such precautions. By fluid retention is meant here the interaction of several, above already partially mentioned influence variables with the aim of achieving the highest possible comfort when wearing the hygiene item on the body.

Non-perforated spun pile materials or staple fiber pile materials based on polyolefins are also used as a surface element for the body-facing covering of the absorbent material.

The fluid management for urine in children's and adult diapers and for menstrual fluids in women's hygiene is considered to be well advanced to fully developed. However, a nappy of the future should not only be able to handle urine in an optimal way, but also liquid discharge from the intestine. Dcke-perforated cover pile fabrics prove unsuitable for this purpose. The body fluids in question are a multiphase system with solid particles in the most different shapes and consistencies with a tendency to phase separation, particularly on active surfaces or surfaces with a filtering and separation effect. The term "intestinal fluids" is used below for these fluids. It has been shown that non-perforated flor materials are unsuitable for completely passing through intestinal fluids and passing these on to the absorbent core. On the contrary, there is a tendency for solid and/or highly viscous portions of the intestinal fluid to be deposited on the diaper surface during separation and may possibly act as a barrier layer for subsequent body fluid with a thin consistency. Both the separation of the coarser components as such and the associated blockage of further fluid transport are serious shortcomings of conventional diapers. There have therefore been numerous proposed solutions for better intestinal fluid management, all of which are based on the fact that perforated topsheets (cover pile fabrics) must be used. The perforation must therefore be clearly formed. Cross-reinforcements between individual fibers or fiber piles, respectively any fiber bridges, have not proven beneficial. In addition to the perforated topsheets, the nappy construction and the creation of the open-structured fleece laid between the cover fabric and the absorbent core must be adapted to the special consistency and the associated peculiarities of the intestinal fluid.

Both numerous perforation methods and also fluorine substances and fluorine substance composites are known. In EP-A-0 215 684, the achievement of perforations in fluorescent materials is described using a water jet technique. As a deposition medium for the fibers and the water jet treatment, the known sieves are not used, but these are replaced by dewatering cylinders which are let into the swellings. These are responsible for a clear perforation. In US 5 628 097, another perforation method and perforated products are described where the fiber material is slit in the longitudinal direction by means of ultrasound or thermally and by passing through one or two interlocking rifled rollers in the form of a pair of rollers for stretching in the transverse direction. The melting area slits are thereby separated and opened to perforations. There are described pile fabrics and endless filaments, melt-blown pile fabrics of staple fibers and endless filaments, melt-blown pile fabrics and composite materials of staple fibers and endless filaments with melt-blown materials, which are for example denoted as SM (for the composite spunbond/melt-blown) or SMS (for the composite spunbond/melt-blown/spunbond).

Perforated polyester fabric in the hygiene area is not only required to maintain intestinal fluid, but also to have the highest possible degree of whiteness, respectively a high covering power and a very high softness, at least on the side facing the body. It is known that both properties depend on the suppleness and softness of the fibers used. This is all the higher the lower the fiber titer is, so that it is obvious to use fine, very fine and ultra fine fibres. Ultrafine fibers are also referred to as microfibers. These can be based on fabrics or floral fabrics. Melt-blown cotton also consists of microfibres in the order of size approx. 1-10 microns.

A children's nappy from the manufacturer Unicharm is known which is covered with a perforated fiber fabric which is produced according to the special water jet perforating method briefly mentioned above and which consists of a composite PP/PE spunbond and a PP meltblown layer. With this composite construction, you certainly have a contribution to better housekeeping for intestinal fluid, a good softness on the meltblown side (= body side) and a high covering power. However, this composite construction and manufacturing method also has serious shortcomings. The melt-blown layer makes no or only a completely insignificant contribution to the total strength or total integrity of the composite. The weight is clearly above what is common today. A weight reduction to below 30 g/m<2>does not seem possible due to the high firmness requirements in the machine direction for diaper production. The high use of materials is cost-intensive. The melt-blown layer considered alone is not wear-resistant and, in addition to the water jet treatment, must also be thermally treated with the spunbond carrier fleece to prevent delamination tendencies. This in turn requires bicomponent fibers (conjugated fibers) with a centric or eccentric sheath component of lower-melting polymer than that in the melt-blown layer. Even so, this perforated SM composite on the soft M side comes very close to the wear resistance found in a PP spunbond or a PP embossed staple fiber pile fabric as they are used today in nappies and sanitary napkins. For other applications such as sealing nappy pant cuffs or OP fleece fabrics where abrasion resistance or lint-freeness is required, only SMS can be used. With such an uncovering of the Meltblown layer on the body side, the advantages of the Meltblown layer will no longer be utilised.

From US 4 840 829 there are known non-woven fabrics with a basis weight of 10 to 150 g/m<2> and which are produced from staple fibers with a length of 20 to 100 mm and a titer of 0.555 to 16.65 dtex. These flor materials have circular or elliptical openings which are obtained by water jet treatment on a substrate equipped with elevations.

Furthermore, from WO98/23804, reinforced non-woven fabrics and methods for producing these are known, consisting of multi-component fibers which, when reinforced into a non-woven fabric, are separated into the individual component fibers and mixed together.

The task of the present invention is to provide a perforated fiber fabric which is superior to the known fiber fabrics in terms of intestinal fluid management, which satisfies the requirements for high opacity and high softness and smoothness on the surface facing the body, which eliminates the need for a two- or multi-layer construction and which has a fiber material weight that is clearly below that of the perforated cotton fabrics used in today's nappies and pads. In addition, the task of the invention is to improve intestinal fluid management without affecting urinary management. Furthermore, it is a task for the invention to achieve fluid passage through the perforated fiber fabric without the use of detergents, or to reduce the quantity of detergents used to a fraction of the usual amounts in the non-perforated enveloping fiber fabrics.

The present invention therefore provides a perforated fiber fabric with a basis weight of 8 to 17 g/m<2> of interwoven endless microfiber filaments with a titer in the range of 0.05 to 0.40 dtex, consisting of at least two thermoplastic polymers with different hydrophobicity and which exhibits a filament cross-section in the form of a cake or hollow cake, from which the split filaments are set free, characterized by the fact that the perforations in the fleece are created open and are free of split fiber filaments, where the perforations are arranged regularly and exhibit a single hole area of 0.01 to 0 .60 cm<2>and the open hole surface is 8 to 40%, whereby the penetration value after 1 minute is less than 3 seconds, the rewetting value is less than 0.5 g and the highest tensile force in the longitudinal direction is at least 30N/5 cm.

Despite their extremely low weight, the fiber fabrics of the invention show very high strengths and, due to the low fiber mass, very clear hole structures. Thereby, it is possible to ensure the rapid passage of body fluids, and especially intestinal fluids, without or only with a very low addition of surfactants with low surface tension (moisturizers), and to provide a dry top layer surface for diapers and sanitary pads.

The different filaments all exhibit a titer within the range indicated above. The perforations are arranged regularly and, as mentioned, have a single hole surface of 0.01 to 0.60 cm<2>.

For the construction of fluorescent material, two different filaments of thermoplastic polymers can be used, for example, in a weight ratio in the range of 20:80 to 80:20. The following explains the construction of the fluorescent material using two filaments Fl and F2.

The invention further provides a method for the production of perforated fiber fabric as discussed above, by laying down and splitting bicomponent filaments with a cross section in the form of cakes or hollow cakes, the cross section of which exhibits at least two different thermoplastic polymers with different hydrophobicity in an alternating cake piece arrangement of a fiber fabric, characterized by that it comprises subsequent splitting and entanglement of the split filaments into tangled microfiber elements by means of high-pressure water jets, and subsequent perforation of the formed fiber material with a high-pressure water jet.

As a result, the perforation takes place preferentially on dewatering and skin formation drums that show elevations on the surface.

The invention further relates to the use of the above-mentioned perforated fleeces as top sheets in hygiene products such as nappies or sanitary napkins.

Below, the polymers used for the production of the fluorescent substances of the invention are first explained, and then the method of production.

Of the two fiber polymers F1 and F2, at least one of the two is hydrophobic and preferably originates from the range of polyolefins, for example polyethylene, polypropylene or copolymers thereof where one of the two is present in excess. The second can be both hydrophobic and also hydrophilic, however is preferably not hydrophilic, but at least less hydrophobic than polypropylene. The stronger hydrophobic fiber polymer is designated here as Fl and the weaker hydrophobic fiber polymer is designated as F2. Fl preferably consists of polypropylene (PP) or polyethylene (PE) or a mixture of the two. F2 can, for example, be a fiber from the range of polyesters such as polyethylene terephthalate, polybutene terephthalate, polypropylene terephthalate or a copolyester thereof, and PE. Neither F1 nor F2 are subject, as far as the choice of polymer is concerned, to any other limitations, except that they must be able to be spun with the known spinnflo methods into conjugated fibres.

Of Fl and F2, both or one of the two may consist of thermoplastic elastomers. Examples of elastic polyolefins for spunbond fabrics can be found in EP-A-0 625 221 and for metallocene-catalyzed LLDPE in EP-A-0 713 546, where also representatives of the weaker hydrophobic elastomers such as polyurethanes, ethylene-butylene-C copolymers, poly (ethylene-butylene), styrene copolymers (kraton), polyadipate esters and polyetherester elastomers (hytel) are described. In the case of these elastomers, it is known that spunbond fabrics can be spun in Meltblown or SMS combinations. The use of such elastomers in F1 and/or F2 increases the softness and suppleness of the perforated microfibre pile fabrics. It has also been shown that kim perforated cotton fabrics, which consist of entangled microfiber endless filaments, show outstanding properties with a view to fluid management. Perforated pile fabrics of similarly entangled microfiber staple fibers do not achieve these improved properties. Due to the wear on the nappy machine alone (high tensile load in the maximum direction), the weight of these in relation to the endless fiber pile fabric must already be multiplied by three on average with a clear sacrifice in perforation quality, flexibility, softness, wear resistance and fluid management.

Also additions of ingredients to the fiber polymer melt in the form of master batches for anti-static treatment, spin dyeing, matting, softening, tackifying and flexibilisation of the fibres, increasing or reducing the repellent properties towards liquid (such as water, alcohols, hydrocarbons or oils) , fat and multi-disperse systems such as intestinal fluids and other liquid bodily secretions such as urine and menstrual fluid, are possible.

Components that change the interfacial tension on the microfiber surface can also be applied by subsequent application after generation or release of the microfiber filaments in the already perforated fiber material. Such substances are, for example, wetting agents in water-dissolved or -dispersed form, with which today many nappy cover spunbond fabrics are equipped with a view to better urine management.

The flor materials according to the present invention are, however, preferably available without such wetting agents, or with only a fraction of the currently common application amounts. The design of the perforations, i.e. the hole size, the shape, the arrangement of the individual perforations in relation to each other (staggered or in a row) and their open surface on one side and the extremely high flexibility of the steps consisting of tangled endless microfiber filaments (area between the perforations) and their very low weight, allows this humectant reduction to the point of complete omission.

The drawings in the form of Figures 1 to 6 explain the invention in more detail.

Figures 1 to 6 show the shape of the individual openings K and their arrangement in a surface element. In Figure 1, K is an idealized opening shown in the form of an equilateral hexagon whereby the side length a is identical to b. The distance o is the shortest distance between the center c of the opening K and the edge a. The edges a and b are always at a constant distance 9 to each neighbor K. In each case, parallel to a and b, a larger equilateral triangle with edges e and f can be placed around the individual openings K. In Figure 1, e = f. This results in a beehive-like arrangement of the openings K The edges a and b in an opening K are always parallel to the neighboring edges a and b in the neighboring opening K. The distance h = 0.59. The tips at the contact edges a with a and respectively a with b are present in a rounded form in the fabric. These roundings i and j of the tips are indicated in Figure 1 for the case i = j. With these roundings, the original distances d to e for the hexagon are shortened to q and r. As regards Figure 1, q = r is thus again.

All rounds i and j can in extreme cases be so greatly expanded that they give a circular shape for K as indicated in Figure 2.

The openings K in Figure 3 differ from those in Figure 1 only in that b is clearly longer than a and that the rounding i is more pronounced than j.

In extreme cases, the roundings i and j can here be so much extended that an elliptical shape arises from the hexagon K, as indicated in figure 4.

Hexagonal shapes for the opening K or such which are formed by rounding these and arrangements thereof as shown in figures 1 to 4, have proven particularly advantageous for the fluid household. Especially with simultaneous hexagonal openings K and their rounded derivatives, body fluids always have the shortest path from the diaper surfaces to the interior of the diaper. However, the invention is not limited to such regular shapes and devices. Also other polygons for K and their rounded variants can be imagined and also irregular distribution of such and other openings. Less suitable, however, are such openings and arrangements thereof where the part of the secreted body fluids which lies farthest from the edge of the opening encounters obstacles to being able to flow out through the openings K in a rapid manner. Such devices are shown, for example, in figures 5 and 6. The distance from the farthest point w to the (rounded) corner of the square is clearly greater than the distance h. The ratio u:h between the maximum distance to the opening K and the minimum distance should i ideally 1:1 and in the worst case no more than 2:1. The single hull surface is in the range 0.01 to 0.60 cm<2> and preferably between 0.01 and 0.40 cm<2>. The individual hole openings can all have the same shape and uniformly have the same hole surface. However, they can differ from each other by one of the two or by both factors, however in compliance with the teaching above with a view to u:h equal to/less than 2:1.

The open hole surface is in the range 8 to 40% and preferably between 12 and 35%.

The microfine, tangled endless filaments s form the frame 1 for the openings. As mentioned above, the perforated fluorescent substance can contain surface-active ingredients that provide a washable, delayed washout or permanent hydrophilicity. These are applied appropriately after the water jet perforation in the wet-on-wet method. The application quantities are between 0 and 0.60% by weight, calculated on flours, preferably between 0 and 0.20%. The dosage depends on the surface of the individual holes and the total open surface. The larger the two are, the more strongly the content of such surfactants can be reduced. With a view to optimal biocompatibility, a surfactant content of 0% is aimed for.

It has proven particularly advantageous that surface-active agents (the surfactant) are not distributed appropriately over the total frame, but are limited to the immediate vicinity of the hole periphery. From here, there is necessarily a suction effect on the fluid directed towards the perforation. The multidisperse fluid system is thereby subject to no dewatering or phase separation. Clogging of the perforation and deposition on the frame is prevented. The fluid absorption and distribution layer inserted between the absorbent core and the top sheet, which is also set to be moisturizing, also supports the immediate removal of body fluid from the nappy surface.

Production of the perforated fiorstoff (top sheet).

This method involves a fissionable cake or hollow cake fiber being deposited using a spinning pile technology into a fiber material consisting of endless filaments. The cross-section of the unsplit fibers emerging from the nozzle consists of two different polymer components Fl and F2 which join each other in alternating order like pieces of cake (usually of 4 to 16 such pieces of cake). As a prerequisite for such a subsequent splitting, the most 2-polymer chemically strongly different components should preferably be used which along the common boundary surfaces only exhibit the lowest possible adhesion. However, chemically similar polymer components such as polyethylene terephthalate and a copolyester or polypropylene and polyethylene can also be used as long as precautions are taken to reduce adhesion at the interfaces between the two, for example by adding a release agent, at least in a fiber polymer component. If the split fiber is internally equipped with a (round) cavity, one speaks of a so-called hollow pie fiber (Hollow-Pie-Faser), otherwise it is a pie fiber (Pie-Faser).

The titer for the endless filaments in the spun pile fabric before splitting is usually 1.0 to 4.0 dtex and preferably 1.6 to 3.3 dtex. The endless filaments in the spunbond fabric are then, by means of methods known per se, such as the high-pressure water jet technique (see for example EP-A-0 215 684), interwoven into each other in a first post-processing step and at the same time split up into the "cake components" . In the case of a cake fiber with a titer of 1.6 dtex and a total of 16 segments which are made up of 8 segments each of the two fiber polymers, there are therefore microfibers after splitting with a titer of 0.01 dtex. As, according to the invention, it concerns a very light fiber material, it is advantageous that the carrier on which the flour is laid out is not a sieve or a carrier with perforations, but a completely imperforated carrier. Thereby, the water jets, by reflection against this carrier, can utilize the shock effect, whereby the energy loss can be minimised.

After the perforation, the whole is either dried or first appropriately brought through a wet-on-wet application process before drying the surfactant with a view to the surface hydrophilicity. This can be done by methods known in and of themselves with full bath impregnation, one-sided immersion, ironing or by pressure. In a particular embodiment, the surfactant or wetting agent is applied in the pattern in such a way that only the boundary areas of the fiber frames around the perforations are affected. This entails the need for the provision of special printing templates which must be adapted to the perforation pattern and which therefore require special control measures to maintain contour sharpness for the wetting agent printing during production.

Example 1.

A spunbond fabric is produced with a basis weight of 13 g/m2 consisting 100% of a cake fiber with a fiber titer of 1.6 dtex, deposited on a sieve. The cake fiber consists in its cross-section of alternating each 8 polypropylene segments and each 8 polyethylene terephthalate segments. The size of the individual polypropylene segments has been chosen so that the proportion by weight of polypropylene is 30% and of polyethylene terephthalate 70%.

The unsplit filaments of endless filaments are placed on a 100 mesh dewatering strainer and fixed with a water jet pressure of 180 mbar and the endless filaments are split into their 8 microfiber segments of polypropylene and 8 microfiber segments of polyethylene terephthalate.

After splitting, the same number of microfiber segments of polypropylene and polyethylene terephthalate is produced each time. The polypropylene microfiber segments exhibit a single titer of 0.06 dtex and the polyethylene terephthalate segments exhibit a single titer of 0.14 dtex. The conversion from dtex to fiber diameter (idealized to round cross sections) gives for polypropylene with a density of 0.91 g/cm<3> a value of 2.36 microns and for polyethylene terephthalate with a density of 0.37 g/cm<3> a value of 4.42 microns.

After splitting the fibers using water jets, the surface element is subjected to a perforation, also using high-pressure water jets with a pressure of 70 kg/cm<2>. Here, the dewatering and hole formation drums described in EP-A-0 215 684 are used with elevations on the surface of the drums instead of the otherwise usual dewatering strainers.

After drying, a very soft, pliable fiber material with clearly formed perforations is produced. The individual holes of the perforation are all (ideally) circular and of the same size. The arrangement of the holes takes place in an orthogonal grid with a grid spacing a, whereby a further grid with holes is arranged centered on the surface.

The radius r averages 1.4 mm and the distance a = 6.0 mm. The open area OF constitutes 34% of the total area.

On this perforated fiber fabric, the highest tensile force in the longitudinal direction according to EDANA 20.289, the liquid strike through time (Liquid Strike Through Time) according to ED ANA 151.3-96 and the Coverstock Wet Back value (also called Rewet) according to EDANA 151.1-96 were measured. .

The passage was repeated after a waiting time of 1 minute, a total of 2 times, without changing the filter paper layers. The stated values are always the mean value of a total of 3 individual measurements.

Results:

Highest tensile force in longitudinal direction: 32.3 N/5 cm

Rewet: 0.09 g

Example 2:

The perforated fluorescent fabric from example 1 was soaked in a foulard by the so-called full bath method with an aqueous emulsion of a non-ionic wetting agent based on polysiloxane. After drying, the amount of solids applied amounted to 0.042% by weight. With this pattern, the following test results were obtained:

Highest tensile force in longitudinal direction: 30.2 N/ 5 cm

Rewet: 0.31 g

Comparison example 1:

A Meltblown layer of 20 g/m<2> was spun on an embossed bonded polypropylene spunbond fabric with endless filaments with a titer of 2.2 dtex and a basis weight of 10 g/m<2>. The average diameter of microfibers that made up this meltblown layer was 3.82 microns. The joining area for the embossed bonded spunbond fabric was 5.2%.

This two-layer laminate was water jet needle punched according to the method described in Example 1 and then perforated on a conventional 20 mesh screen web. The open surface was calculated at 18.4%. This two-layer non-woven fabric was also very soft, but gave clear deficiencies with regard to the highest tensile force and penetration compared to the test values measured in examples 1 and 2. Penetration and Rewet were measured in each case on the PP meltblown side.

Highest tensile force in longitudinal direction: 25.4 N/5 cm

Rewet: 0.10 g

The pass-through value was clearly too high for a top sheet.

Comparison example 2:

In the same way as in comparative example 1, 0.40% nonionic wetting agent based on polysiloxane was applied. As the measured values show, the penetration value can thus be greatly reduced, but the Rewet value was disproportionately increased. Such high rewetting cannot be accepted in a nappy.

Results:

Highest tensile force in longitudinal direction: 24.6 N/ 5 cm

Rewet: 2.35 g

The melt-blown layer gave the top layer a high softness. In the presence of a wetting agent, however, this meltblown layer acted like a sponge. Such a construction therefore proved unsuitable as a cover layer for a suction layer.

Comparison example 3:

The two-layer product described in comparative example 1 was subjected to a water jet treatment according to example 1.

The average radius r for the holes after the water jet perforation was r = 1.28 mm. The distance a remained unchanged at a = 6.0 mm.

An open surface OF = 28.6% was calculated.

Results:

Highest tensile force in longitudinal direction: 24.2 N/5 cm

Rewet: 0.10 g

The pass-through values were once again too high.

Claims (7)

1. Perforated fiber fabric with a basis weight of 8 to 17 g/m of interlaced endless microfiber filaments with a titer in the range of 0.05 to 0.40 dtex, consisting of at least two thermoplastic polymers of different hydrophobicity and exhibiting a filament cross-section in cake or hollow cake form, from which the split filaments are set free, characterized by the fact that the perforations in the fleece are created open and are free of split fiber filaments, where the perforations are arranged regularly and exhibit a single hole surface of 0.01 to 0.60 cm<2> and the open hole area is 8 to 40%, whereby the penetration value after 1 minute is less than 3 seconds, the rewetting value is less than 0.5 g and the highest tensile force in the longitudinal direction is at least 30N/5 cm. 2. Perforated fluorescent fabric according to claim 1, characterized in that the ratio between the maximum distance from the points on the floor surface to the next perforation and the minimum distance amounts to 1:1 to 2:1. 3. Perforated fluorescent material according to claim 1 or 2, characterized in that the perforated fluorescent material is made up of polyolefin and polyester filaments in a weight ratio in the range of 20:80 to 80:20. 4. Perforated fluorescent material according to any one of claims 1 to 3, characterized in that the fluorescent material is impregnated with 0 to 0.60% by weight calculated on the fluorescent material The weight of at least one surface-active material. 5. Process for the production of perforated fior fabric according to any one of claims 1 to 4, by depositing cleavable bicomponent filaments with a cross section in the form of cakes or hollow cakes whose cross section exhibits at least two different thermoplastic polymers of different hydrophobicity in an alternating cake piece arrangement of a fior fabric, characterized in that it comprises subsequent splitting and entanglement of the split filaments into entangled microfiber elements using high-pressure water jets, and subsequent perforation of the formed fiber material with a high-pressure water jet. 6. Method according to claim 5, characterized in that the perforation takes place on dewatering or skin-forming drums which exhibit elevations on the surface. 7. Use of perforated nonwovens with a basis weight of 8 to 17 g/m<2> of interwoven endless microfiber filaments with a titer in the range of 0.05 to 0.40 dtex, consisting of at least two thermoplastic polymers of different hydrophobicity and exhibiting a filament cross-section in cake or hollow-cake shape, from which the split filaments are set free, whereby the perforations in the fleece are created open and are free of split fiber filaments, where the perforations are arranged regularly and exhibit a single hole surface of 0.01 to 0.60 cm and the open hole surface is 8 to 40%, whereby the penetration value after 1 minute is less than 3 seconds, the rewetting value is less than 0.5g and the highest tensile force in the longitudinal direction is at least 30N/5cm, as a top sheet in hygiene products such as diapers or sanitary napkins .