CA2346889C - Perforated non-woven and process for it's manufacture - Google Patents

Abstract

Disclosed is a perforated bonded fiber fabric with a surface weight of 8- 17g/m2. The inventive fabric consists of continuous intertwined microfiber filaments wit h a titer that ranges from 0.05 0.40 dtex. Said filaments consist of at least two different types of filaments made from thermoplastic polymers with different hydrophobicities and a fiber cros s section resembling the portions of a cake. The filaments are devoid of any conglutinations or fusions, especially in the region of the perforations.

Description

Perforated Non-woven and Process For It's Manufacture l3ody liquids absorbing hygienic products, such as baby diapers, adult diapers, or feminine napkins are principally made of an absorbent core, a sealing back sheet made of a foil or a non-woven/foil laminate and a body side permeable sheet made of a thin, wear-resistant and soft non-woven or a vacuum perforated foil with funnel-shaped, ie. three-dimensional openings. The vacuum perforated foil encloses the absorbent core, whereby the largest perforation opening is directed outwardly, which means toward the body. The material of the foil is a hydrophobic thermoplastic polymer such as polyethylene, polypropylene or a copolymer of ethylene and polyvinyl acetate (EVA). With this it is achieved that the ~~urface of the foil is not wetted by the body fluid, the body fluid is conducted only toward the absorbing core and a strike back thereof upon load, movement or pressure is prevented by the inwardly tapered perforations. It is known to generally include superabsorbing particles (SAP) in the absorbent core apart from the predominant fluff. Superabsorbent polymers are characterized in that they can take up large amounts of aqueous fluids, forming a gel body with a relatively low gel strength while ~,ignificantly increasing in volume. The presence of SAP has the advantage of the weight being reduced and thereby also the thickness of the absorbent core being reduced so that leakages can be largely prevented. However, SAP also has the disadvantage that it leads to the well-known gel blocking which is more pronounced, the higher its proportion. Gel blocking refers to the effect when liquid can no longer be transported or only at a significantly lower rate. This problem was also solved by suitable construction of the absorbent hygienic products. In that case, high volume non-wovens or other very open structures which do not have a blocking effect upon liquid contact are positioned between the absorbent core and the cover sheet. This intermediate layer immediately takes up liquid, which means it removes it spontaneously from the diaper surface and distributes it evenly .
The fluid management is improved by these measures. Fluid management here refers to the interplay of many of the above already mentioned variables with the goal to produce the highest possible comfort during the wearing of the hygienic article on the body.
It is also known to use unperforated spun non-wovens and staple fibre non-wovens on the basis of polyolefins as sheets for the body side covering of the absorbent material.
'Che fluid management for children and adult diapers and menstrual fluids in feminine napkins are considered advanced and sophisticated. However, a diaper of the future should not only be able to manage urine in an optimal manner, but also watery bowel secretions.
Unperforated cover non-woven materials have proven unsuitable for this purpose. The respective body fluid is a multi phase system 'with solid particles of different form and consistency with a tendency to phase separation, especially on ;active surfaces or surfaces with filtration or separation activity. These liquids are in the following preferred to under the term bowel fluids. It has been shown that unperforated non-wovens are unsuited to let bowel fluids completely pass and to pass them on to the absorbent core.
Rather, the tendency exists for solid and/or highly viscus components of the bowel fluid to accumulate on the diaper surface ~~ia separation and to possibly act as a blocking layer for subsequently following body fluids 'with more l iquidy consistency. The separation of the more coarse components in itself as well as the associated blockage for further fluid transport are aggravating disadvantages of conventional diapers. Therefore, numerous solutions for improved bowel fluid management have been proposed, all of which are based on the use of perforated top sheets (non-woven cover materials). The perforations should thereby be clearly formed. Cross braces of individual fibres or fibre bundles or any fibre bridges have thereby proven disadvantageous. In addition to the perforated top sheets, the construction of the diaper and the ~~tructure of the open-structured non-we>ven located between the non-woven cover material and the absorbent core should be adapted to the special consistency of the bowel fluid and the associated properties.
lslumerous perforation methods as well as non-wovens and non-woven composites are known. The manufacture of perforations in non-wovens with the help of water jet technology is described in 1?P-A-0 215 684. The already known sieves are not used as supporting media for the fibres and water jet treatment, but are replaced by dewatering cylinders into which protrusions have been embedded.
'Chose are responsible for a clear perforation. Another perforation method and perforated product are described in US 5,628,097 wherein the non-woven material is ultrasonically or thermally split in longitudinal direction and transversely stretched by passage through a roller pair consisting of two interlocking grooved rollers. The melting point slits are thereby separated and opened to form perforations. Described are non-wovens made of staple fibres and endless filaments, meltblown non-wovens and composites of staple fibres and endless .filaments with meltblown, which are referred to as SM (for a spunbond/meltblown composite) or SMS (for a composite of ~~punbond/meltblown/spunbond).
~~ perforated non-woven for the hygiene field is expected not only to allow bowel fluid management but ., ;also to have the highest possible degree of whiteness or a high covering power and a very high softness .at least on the body side surface. It is known that both of these properties depend on the suppleness and softness of the fibres used. They are the higher the lower the fibre titre, so that it presents itself to use :fine, very fine or ultra-fine fibres. Ultra fine fibres .are also referred to as micro fibres. They can be on ~~ fabric or non-woven basis. Meltblown non-wovens also consist of micro fibres in the range of 1-10 microns.
.A baby diaper is known from the manufacturer UNICHARM which diaper is covered by a preferred non-woven which was manufactured with the above briefly described special water jet perforation method and consists of a composite PPiPE spunbond and a PP meltblown layer.
This laminate construction contributes to a better management of the bowel fluid, a good softness on the meltblown side (=bodyside) and guarantees a high covering power. However, this laminate construction and method of manufacture also have aggravating disadvantages. The meltblown layer provides no, or only a completely insignificant, contribution to the overall strength or overall integrity of the laminate. The ~Neights are thereby clearly above those of today's standard. A weight reduction to below -30 g/m2 appears impossible because of the high strength requirements in the machine direction for diaper manufacture. The high material use is cost intensive. The meltblown layer in itself is not abrasion resistant and, in addition to the water jet treatment, must be firmly anchored to the spunbond carrier non-woven in order to prevent delamination tendencies. This in turn requires bi-component fibres (conjugated fibres) with a concentrical or eccentric sheath component of a polymer melting at a lower temperature than the meltblown layer. Still, on the soft M-side this perforated SM-composite does not reach by far the abrasion resistance of a PP-spunbond or a PP-embossment bound staple fibre non-woven material as used in diapers and feminine napkins today. For other uses, such as sealing training-pants cuffs or OP-non-wovens for which abrasion resistance or freedom from lint is required, only SMS can be used. The advantages of the meltblown layer would no longer have a bearing if the meltblown layer had such a covering on the body side.
l~lon-woven materials with a surface weight of 10-150 g/mZ are known from US
4,840,829, which were made from staple fibres with a length of 20-100 mm and a titre of 0.555-16.65 dtex. These non-woven materials have circular or elliptical openings which were produced by water jet treatment on a ~,upporting surface provided with protrusions.
_ 7_ Furthermore, solidified non-wovens and processes for their manufacture are known from the document W098/23804, which consist of multi-component fibres and which during their solidification to a non-woven are separated into their individual component fibres and entangled.
The invention may advantageously provide a perforated non-woven which is superior to conventional non-wovens for bowel fluid management, complies with the requirements for high opacity, high softness and delicateness to the bodyside surface, obviates a two or more layer construction and can be achieved at a fibre material weight which is significantly lower than that of perforated non-wovens currently used in diapers and feminine napkins. The invention may advantageously improve bowel fluid management without interference with urine management. Furthermore, the invention may advantageously achieve fluid passage through the perforated non-woven without the use of detergents or to reduce the amount deployed to a fraction of the amounts conventional in non-perforated non-woven wrap materials.
An aspect of the invention provides a perforated non-woven with a surface weight of 7-25 g/mz and made of entangled endless microflbre filaments with a titre in the range of 0.05-0.4 dtex, which are made of at least two thermoplastic polymers with different hydrophobicity and have a pie-shaped or hollow pie-shaped filament cross-section from which split filaments have been released, wherein the perforations are clearly formed and are free of split-fibre filaments.
Despite an extremely low weight, the non-woven in accordance with the invention exhibit a very high strength and, because of the low fibre mass, very clear aperture structures.
It is thereby possible to guarantee the fast passage of body fluids, especially bowel fluids without using any or only small amounts of added surface active compounds with low surface tension (surfactants) and to produce a dry top sheet surface for diapers and feminine napkins. , The individual filaments respectively have a titre in the above mentioned range. The perforations are preferable evenly distributed and have an individual aperture surface of 0.01-0.6 cmz.
The perforated non-woven in accordance with the invention preferably has a strikethrough value at one minute of less than 3 seconds. The maximum strength in longitudinal direction is preferably at least 30 N/Scm. The re-wet value is preferably less than 0.5 g.

'Two different filaments of thermoplastic polymers can be used, for example, for the construction of the non-woven which are used in a weight ratio in the range of 20:80 to 80:20. The construction of the fibrous non-woven is in the following described by way of two filaments F1 and F2.
'The invention also relates to a process for the manufacture of such perforated non-wovens by depositing splittable pie or hollow-pie endless fibres into a non-woven, the cross-section of the fibres iincludes at least two different thermoplastic polymers with different hydrophobicity in an alternating pie-shaped arrangement, subsequent splitting and entanglement of the fibres to entangled endless fibres with the help of high pressure water jeta, and subsequent perforation of the non-woven thus formed with high pressure water jets. The perforation is thereby preferably carried out on dewatering and aperture forming drums which have protrusions on their surface.
l:n the following, the polymers used for the manufacture of the non-woven in accordance with the invention are described first and then the manufacturing process itself.
~~t least one of the two fibre polymers F1 And F2 is hydrophobic and is preferably derived from the line of polyolefins, such as polyethylene, polypropylene or copolymers thereof, whereby one of the two is present in excess of the other. The other can be hydrophobic or hydrophilic, but is preferably not hydrophilic while still less hydrophobic. than polypropylene. The more strongly hydrophobic polymer is here referred to as F1 and the less hydrophobic polymer as F2. F1 is preferably made of polypropylene (PP) or polyethylene (PE) or of mixtures thereof. F:' is preferably a fibre from the line of polyesters, ~~uch as polyethylene terephthalate, polybutylene terephthalate, polypropylene terephthalate or a copolymer thereof and PE. As far as the selection of the polymer is concerned, F1 as well as F2 are not subject to any other restriction, except that it must be possible to spin the two conjugated fibres in the known non-woven spinning processes.
(one or both of F1 and F2 can consist of a thermoplastic elastomer. Examples of elastic polyolefins for ~~pun non-wovens are found in EP-A-0 625 221 and for metalocene catalysed LLDPE (linear low density polyethylene) in EP-A-0 713 546, in which are also described the representatives for the less hydrophobic elastomers such as polyurethanes, ethylene-butylene copolymers, polyethylene-~butylene) ~~tyrole copolymers (Kraton), poly-adipate-esters and polyetherester elastomers (Hytrel). It is known that spun non-woven materials can be spun in meltblown or SMS-combinations from these elastomers.
_ ,_ 'The use of such elastomers in Fl and/or F2 increases the softness and suppleness of the perforated micro fibre non-woven. It has further been found that only perforated non-wovens which consist of mutually entangled micro fibre endless filaments exhibit the excellent properties with respect to fluid management. Perforated non-wovens of similarly mutually entangled micro fibre staple fibres do not ~ichieve these improved properties. For the processing on diaper machines alone (high tension stress in machine direction) the weight of such a non-woven would have to be tripled on average relative to the endless fibre non-woven, with significant reduction in perforation quality, suppleness, softness, abrasion resistance and fluid management.
la is also possible to add ingredients to the fibre polymer melt in the form of master batches for the purpose of anti-static finish, spin coloring, rendering languid, softening, rendering tacky and fibre l7exibility, or to increase or decrease the recurring properties with respect to liquids (such as water, alcohol, carbohydrates, oils), fats and multi dispersed systems, such as bowel fluids and other liquid body excretions such as urine and menstrual fluid.
Ingredients which change the surface tension at the surface of the micro fibres can also be applied by applications subsequent the generation or release of the micro fibre filaments in the already perforated non-woven material. Such compounds are, for example, surfactants dissolved in water or in dispersed form with which many diaper cover sheet spunbond non-wovens of today are treated for the purpose of improved urine management.
l3owever, the non-woven material in accordance with the present invention can function without such ~;urfactants or with only a fraction of the conventional application amount.
The structure of the perforations, which means their aperture size and shape, the position of the individual perforations to one another (for example staggered or in line) on the open surface, as well as the extremely high ~;uppleness of the webs (region between the perforations) consisting of the entangled micro fibre filaments and their very low weight provide for this surfactant reduction to the point of complete f;limination.
'Che drawing with the Figures 1-6 additionally describes the invention.
'Che shape of the individual openings K and their positioning in a sheet is shown in Figures l-6. In -t>-Figure 1, K is an idealistically illustrated opening in the shape of an even sided hexagon, whereby the length a and b of the sides is identical. The distance o is the shortest distance between the centre c of the opening K and the edge a. The edges a and b are respectively at a constant distance g to each neighbouring K. A larger even sided hexagon with the edges a and f can be positioned around the individual openings K and oriented in parallel to a and b. In Figure 1, e=f.
This creates a honeycomb type arrangement of the openings K. The edges A and b of one opening K are respectively parallel to the neighbouring edges a and b of the neighbouring openings K. The distance h=0.5g. The corners at the contact points of a with a or a with b are of rounded shape in the non-woven. This rounding i and j of the corners is shown in Figure 1 for the case i=j. Because of these roundings, the original distances d and a of the hexagon are shortened to q and r. In the case of Figure 1, it is again q=r.
All roundings i and j can be widened in the extreme case to such a degree that a circular shape results for K, as demonstrated in Figure 2.
The openings K of Figure 3 are distinguished from those of Figure 1 only in that b is significantly longer than a and the rounding i is more pronounced than j.
In the extreme case, the roundings i and j can be widened to such a degree that an elliptical shape results from the hexagonal a, as illustrated in Figure 4.
Hexagonal shapes of the openings K or those which result by the rounding thereof and their orientation, as illustrated in Figures 1-4 have proven especially preferable for fluid management. Especially with even sided hexagonal openings K and their rounded derivatives, the body fluids always have the shortest way from the diaper surface to the diaper interior. However, the invention is not limited to such symmetrical shapes and arrangements. Other polygons and their rounded derivatives are conceivable for K as well as irregular distributions of such openings and others. However, less suited are those openings and arrangements thereof which provide an impediment to the fast drainage through the openings K of that portion of the excreted body fluid which is furthest away from the edge of the opening. Examples of such arrangements are shown in Figures S and 6.
The distance from the furthest point w to the (rounded) corner of the square is significantly larger than the distance h the ratio u/h of maximal distance to the opening K to minimal distance should in the ideal case be 1:1 and in the worst case not above 2:1.
'The individual aperture surface is in the range of 0.01-0.06 cm2, preferably between 0.04 and 0.4 cm2.
'The individual apertures can all have the same shape and aperture surface.
However, one or both of them can be different as long as the above mentioned rule of u/h <_2:1 is observed.
'The open aperture surface is in the range of 8-40 % , preferably between 12 and 35 % .
'The microfine entangled filaments S form the frame L for the openings. The perforated non-woven ran, as mentioned above, include surface active substances which provide it with hydrophylicity which ran be flushed out, delayed flushed out or which is permanent. They are preferably applied after the water jet perforation in a wet-in-wet process. The application amount is between 0 and 0.6 weight relative to the weight of the non-woven, preferably between 0 and 0.2 % . The dosage depends on the surface area of the individual openings and the total open area. The larger the two, the more the content of such surfactants can be reduced. For reasons of optimal biocompatibility, a surfactant content of 0 % is desired. It has been proven advantageous to distribute the surface active agent (surfactant) not evenly over the whole frame but to limit it to only the immediate vicinity of t:he ;rperture periphery. This necessarily then creates from this location a suction action on the fluid which i,s directed towards the perforation. The mufti-dispersed system does then not suffer dewatering or face separation. A blocking of the perforations and deposit on the frame is thereby prevented. The fluid receiving and distributing layer positioned between the absorbent core and the top sheet which is also ;rdjusted to have wetting properties, further promotes the immediate removal of the body fluid from the diaper surface.
Manufacture of the Perforated Non-woven (Top Sheet) 'The process consists in that a splittable pie or hollow pie fibre is deposited with the help of non-woven spinning technology into a non-woven material of endless filaments. The cross-section of the fibres exiting the nozzle in the unsplit condition consists of the two different polymer components F1 and F2 which are alternatingly aligned like pie shapes (4-lE~ of such pie shapes in a normal case). As a i~rerequisite for a subsequent splitting, two components of strongly different polymer chemistry are ipreferably used which exhibit the smallest possible adhesion at the mutual engagement surfaces.

However, chemically similar polymer components can also be used, for example, polyethylene terephthalate and a copolyester or polypropylene and polyethylene, as long as measures have been taken to reduce the adhesion at the mutual engagement surfaces of the two, for example by the addition of separating agents in at least one of either polymer or component. When the splittable fibre is provided at its interior with a (rounded) cavity, it is referred to as a so called hollow pie fibre, and otherwise as a polyfibre.
The title of the endless filaments in the notable spunbond before the splitting is generally 1.0-4.0 dtex, preferably 1.6-3.3 dtex. The endless filaments of the non-woven spunbond are subsequently entangled by way of known methods of the high pressure water jet technology (see for example EP-A-0 215 684) in a first downstream treatment step and simultaneously split into the pie components. Thus, micro fibres with a titre of 0.10 dtex result after the splitting of a pie fibre with a titre of 1.6 dtex and a total of 16 segments, which are composed of 8 segments each of the two fibre polymers.
Since the non-woven in accordance with the present invention is very light, it is advantageous to use as support for the non-woven not a sieve or a support with perforations, but a completely unperforated support. The reflection effect due to deflection of the water jets on this support can be exploited in this way and the energy loss thereby minimized.
After perforation, either a drying is carried out, or prior to that a detergent is applied, preferably with a wet-in-wet application method, for the purpose of hydrophylising the surface.
This can be carried out in accordance with the known methods of full bath impregnation, one sided splattering, wiping or printing. In a special embodiment the detergent (surfactant) is printed on in a pattern in such a matter that only the fringe regions of the fibre frame of the perforations are affected. This requires the production of special printing templates which must be adapted to the perforation pattern as well as special control measures for maintaining the edge definition of the surfactant print during manufacture.

A spun non-woven with a surface weight of 13 g/m2 which consists to 100 % of a pie fibre with a fibre titre of 1.6 dtex is laid down on a sieve. In cross-section, the pie fibre consists of 8 polypropylene segments respectively alternating with 8 polyethylene terephthalate segments.
The size of the individual polypropylene segments being selected such that the proportion by weight of the polypropylene is 30 %

and of the polyethylene therephthalate is 70% .
The unsplit endless filament non-woven is deposited onto a 100 mesh dewatering sieve and solidified with a water jet pressure of 180 millibar, and the endless filaments are respectively split into their 8 micro fibre segments of polypropylene and 8 micro fibre segments of polyethylene terephthalate.
After the splitting. respectively the same number of micro fibre segments of polypropylene and polyethylene terephthalate are present. The micro fibre segments of polypropylene have an individual titre of 0.06 dtex and the segments of polyethylene terephthalate have an individual titre of 0.14 dtex.
The conversion of dtex into fibre diameter. (approximated for a round cross-section) results for polypropylene (density of 0.91 g/cm') in a value of 2.36 micron and for polyethylene terephthalate (density of 1.37 g/cm') in a value of 4.42 micron.
After the splitting of the fibres by way of water jets, the web is subjected to a perforation also by way of high pressure water jets with a pressure of 70 kg/cm'. For this purpose, the dewatering and aperture forming drums described in EP-A-0 215 684 which have protrusions on the surface of the drum are used instead of the otherwise conventional dewatering sieves.
After the drying, a very soft and pliable non-woven is formed with clearly formed perforations. The individual apertures of the perforation are all (ideally) of circular shape and of the same size. The apertures are positioned in an orthogonal grid with a grid spacing a, whereby a further grid with apertures is overlaid and respectively centred with respect to the surface area.
The average radius r is 1.4 tnm and the distance a is 6.Omm. The open surface OF is 34 % relative to the total surface. , The maximum tension strength in longitudinal direction of the non-woven was measured according to EDANA20.289, the liquid strike through time according to EDNA 150.3-96 and the cover stock wet back (also called rewet) according to EDNA 151.1-96.
The strike through was repeated twice after a waiting period of 1 minute respectively without changing the filter paper layers. The values given are respectively the averages from three individual measurements.
RESULTS:
Maximum tension strength in longitudinal direction: 32.3 N/ 5 cm.
1. Strike Through 2. Strike Through 3. Strike Through (sec) (sec) (sec) Immediately After one minute After a further minute 1.82 2.42. 2.44 Rewet: 0.09g Example 2 The perforated non-woven from Example 1 was impregnated in the foulard by the so called full-bath method with an aqueous emulsion of a non-ionic surfactant on the basis of polysiloxane. The amount of solid applied after drawing was 0.042 wt% . The following test results were achieved with this sample:
Maximum tension strength in longitudinal direction: 30.2 N/Scm.
1. Strike Through 2. Strike Through 3. Strike Through (sec) (sec) (sec) Immediately After one minute After a further minute 1.58 2.10 2.11 Rewet: 0.31g Comparative Example 1 A meltblown layer of 20 g/mz is spun onto an embossment bonded spun non-woven of polypropylene with endless filaments with a titre of 2.2dtex and a surface weight of 10 g/m~. The average diameter of the micro fibres forming the meltblown layer was 3.82 micron. The meltbonded surface of the embossment bonded spun non-woven was 5 .2 % .

This dual layer laminate was water jet needled according to the method described in Example 1 and subsequently perforated on a conventional 20 mesh sieve web. The open surface was calculated at 18.4 % . The dual layer fleece was also very soft, but had significantly lower maximum tension strength and strike through compared to the test values measured in examples I and 2.
Strike through and rewet were respectively measured on the PP-meltblown side.
Maximum strength in longitudinal direction: 25.4 N/Scm.
1. Strike Through 2. Strike Through 3. Strike Through (sec) (sec) (sec) Immediately After one minute After a further minute 3.81 4.92 4.96 Rewet: 0. lOg The strike through values are clearly too high for a topsheet.
Comparative Example 2 0.40 % of a non-ionic surfactant on the basis of polysiloxane was applied to a sample of the comparative Example 1. Although the strike through can be significantly lowered in this manner as will be apparent from the test results, the rewet is disproportionately much higher. Such a high rewetting cannot be accepted in a diaper.
Results Maximum tension strength in longitudinal direction: 24.6 N/Scm.
1. Strike Through 2. Strike Through 3. Strike Through (sec) (sec) (sec) Immediately After one minute After a further minute 1.23 2.35 2.40 Rewet: 2.35g 'The meltblown layer provides a topsheet with a high softness. However, in the presence of the surfactant, this meltblown layer acts as a sponge. Such a construction is therefore unsuited for the ~:overing of an absorbent layer.
Comparative Example 3 'The two-layer construction described in Comparative Example 1 is subjected to a water jet treatment ~rccording to Example 1.
'The average radius of the apertures after the water jet perforation was r=1.28mm. The distance a remained unchanged at a=6.Omm.
.An open surface OF=28.6% was achieved.
lEtesults Maximum strength in longitudinal direction: 24.2 N/Scm.
1. Strike Through 2. Strike Through 3. Strike Through (sec) (sec) (sec) Immediately After one minute After a further minute

2.93 3.78. 3.84 Ltewet: I . l Og 'The strike through values were again too high.

Claims (11)

CLAIMS:

1. A perforated non-woven material with a surface weight of 8-17 g/m2 of entangled endless micro fibre filaments with a titre in the range of 0.05-0.40 dtex which are constructed of at least two thermoplastic polymers with different hydrophobicity and have a filament cross-section in pie or hollow-pie shape from which split filaments have been released, wherein the perforations are clearly formed and are free of split fibre filaments.

2. Perforated non-woven according to claim 1, wherein the perforations are evenly distributed and have an individual aperture surface of 0.01-0.6 cm2.

3. Perforated non-woven according to claim 1 or 2, wherein in the non-woven material the ratio of maximum to minimum distance of points on the non-woven surface to the closest perforation is 1:1 to 2:1.

4. Perforated non-woven according to any one of claims 1 to 3, wherein the open aperture surface is 8-40%.

5. Perforated non-woven according to any one of claims 1 to 4, wherein the perforated non-woven is made of polyolefin and polyester filaments in a weight ratio in the range of 20:80 to 80:20.

6. Perforated non-woven according to any one of claims 1 to 5, wherein the non-woven is impregnated with a surface active substance in an amount of at least 0-0.60 wt.% relative to the weight of the non-woven.

7. Perforated non-woven according to any one of claims 1 to 6, wherein the strike through value after 1 minute is less than 3 seconds, the rewet value is less than 0.5 g and the maximum tension strength in longitudinal direction is at least 30 N/5 cm.

8. Process for the manufacture of a perforated non-woven according to any one of claims 1 to 7, comprising the steps of laying down splittable pie or hollow-pie endless fibres, a cross-section of which includes at least 2 different thermoplastic polymers with different hydrophobicity in an alternating pie piece arrangement into a non-woven material, splitting the fibres and entangling the split filaments to form entangled micro fibre filaments by way of high-pressure water jets, and subsequently perforating the formed non-woven with high-pressure water jets.

9. Process, according to claim 8, wherein the perforating is carried out on dewatering and aperture forming drums which have protrusions on their surface.

10. Use of a perforated non-woven according to any one of claims 1 to 7, as topsheet in hygienic products.

11. Use according to claim 10, wherein the hygienic products are diapers or feminine napkins.