SK285887B6 - Perforated bonded fiber fabric - Google Patents

Abstract

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

Description

Technical field

Hygiene articles absorbing body fluids, such as baby diapers, adult diapers, or sanitary napkins, are essentially comprised of an absorbent core, a foil or backing sheet / laminate, and a permeable flat face of thin and soft fleece on the body side. abrasion resistant or vacuum perforated foil with three-dimensional funnel-shaped openings. The vacuum perforated film forms a core absorbent shell, with the larger aperture opening facing outwardly, that is, towards the body. The film material is a hydrophobic thermoplastic such as polyethylene, polypropylene, or ethylene-polyvinyl acetate (EVA) copolymer. This ensures that the surface of the film is not wetted by body fluids, body fluids are directed solely in the direction of the absorbent core, and their backward displacement, for example under load, movement or pressure, is prevented by a tapering inward. As is known, the absorbent core usually contains superabsorbent (SAP) particles in addition to the predominant pulp. Polymer superabsorbents are characterized in that they can absorb body fluids in considerable amounts, while forming a gel structure with a more or less reduced gel stability with a significant increase in volume. The presence of SAP has the advantage of saving weight, and therefore the thickness of the absorbent core can also be reduced, and that the liquid cannot be released again at, for example, pressure, thereby largely preventing leakage. However, the disadvantage of SAP absorbent is that its use leads to a known gel blockage, the more the greater its proportion. By gel blocking is meant the effect that the liquid can no longer be transported, or only at a considerable slowdown. However, by suitable construction of absorbent sanitary articles, this problem has also been solved by placing bulky webs (nonwoven fabrics) or other very open and non-blocking structures in contact with the liquid. This intermediate layer absorbs liquid immediately, that is, spontaneously removes it from the diaper surface and distributes it evenly. This measure greatly improves fluid management. By fluid control we understand the cooperation of many of the previously mentioned factors to create the best possible comfort when wearing hygiene products on the body.

As is known, non-perforated, spunbonded and nonwoven webs of polyolefin-based fibers are also used as flat textile layers for covering the absorbent material on the body side.

Fluid control is considered to be very advanced to overworked in the case of urine in baby diapers and adult diapers, as well as in menstrual fluids for sanitary napkins. However, the diaper of the future should not only be able to optimally control urine, but also thin intestinal products. Non-perforated cover webs, however, appear unsuitable for this purpose. This body fluid is a multi-phase system with solid particles in various forms and consistencies with a tendency to phase separation, especially on active surfaces or surfaces with a filtering and separating effect. For these fluids, the term intestinal fluids is used hereinafter. It has been shown that non-perforated webs are not suitable for intestinal fluid to be perfectly permeated to the absorbent core. In addition, there is a tendency that solid and high viscous proportions of intestinal fluid due to separation are deposited on the diaper surface and the resulting layer subsequently acts as a closure for the next bodily fluid with a thin consistency. The separation of the coarser components and the associated blockage of further fluid transport are significant drawbacks of the present diapers. Therefore, there are many suggestions for improving intestinal fluid control, all based on the assumption that perforated nonwoven fabrics must be used. It is necessary to create perforations in clean contours. Cross reinforcements with individual fibers, fiber bundles or some fiber bridges are adversely affected. By means of the perforated covering webs, both the diaper designs and the open-structure web characteristics interposed between the covering web and the absorbent core should be adapted to the properties of the intestinal fluid.

BACKGROUND OF THE INVENTION

As with many perforation methods, several types of nonwoven and composite webs are known. EP-A-0 215 684 discloses the perforation of the webs using the water jet technique. Known sieves, which are replaced by dewatering rollers with ridges (spines), are not used to store the fibers in the waterjet treatment. Their job is to create clean perforations. U.S. Pat. No. 5,628,097 discloses another perforation method and its products in which the web is longitudinally ultrasonically or thermally vaporized and expanded transversely by passing through one of a pair of rollers formed by two interlocking raster calenders. This separates the cracks at the welds and opens them as perforations. Described are nonwoven fabrics of length and filaments sorted, meltblown webs and composite products of length and filaments sorted with meltblown, referred to as SM (spunbond / meltblown composite) or SMS (spunbond / meltblown composite) spunbond).

In the hygiene field, the perforated web is required not only to control intestinal fluids, but also to provide the highest whiteness and good hiding power and very high softness at least on the side facing the body. It is known that both properties depend on the flexibility and softness of the fibers used. This is the higher the lower the fiber titer, so it is possible to use fine, finest or even ultra-fine fibers. Ultrafine fibers are also referred to as microfibers. They can be used in fabrics and nonwovens. Also, the meltblown webs are microfibers in the range of about 1 to 10 µm.

A children's diaper of Unicharm is known, covered with a perforated nonwoven fabric made according to the briefly described method of special water jet perforation and consisting of a composite web of PP / PE spunbond and a meltblown PP layer. Indeed, this composite construction provides better intestinal fluid control, good softness on the body-facing meltblown side, and high hiding power. However, this composite construction and its method of manufacture exhibit significant drawbacks. The meltblown layer does not contribute (or only slightly) to the overall strength or compactness of the system, respectively. The weights are well above the usual values today. A weight reduction below about 30 g / m ² does not seem possible due to the high strength requirements in the mechanical production of diapers. Considerable material consumption increases costs. The Meltblown layer is not abrasion-resistant in itself and must still be anchored in the spunbonded nonwoven prior to perforation with a water jet to prevent delamination. This in turn requires bicomponent fibers with a central or eccentric sheath component of a polymer set at a lower temperature than the meltblown layer. Nevertheless, this perforated system does not reach

The SM on the soft meltblown side is not nearly as abrasion-resistant as a combination of spunbond-PP or a length-graded fiber web associated with a PP screen roller, which is now used in both diapers and sanitary napkins. For other applications, such as sealed diaper cuffs or OP fleece, where abrasion resistance or non-loose textile dust is required, only SMS can be used. With similar coverings of the meltblown layer on the body side, the advantages of the meltblown layer would no longer be apparent.

U.S. Pat. No. 4,840,829 discloses webs having a basis weight of 10 to 150 g / m @ ² made from sorted fibers of 20 to 100 mm length and a fineness of from 0.555 to 16.65 dtex. These webs have circular or elliptical perforations, which are obtained by treatment with water rays on the mandrel substrate.

Furthermore, WO 98/23804 discloses reinforced webs and a process for their production, consisting of multicomponent fibers which, when stiffened to a non-woven fabric, are fiberized to individual constituent fibers as they are coiled.

SUMMARY OF THE INVENTION

SUMMARY OF THE INVENTION The object of the invention is to provide a perforated web which is superior to the prior art web for the control of intestinal fluids, meets the requirements for high capacity and higher whiteness and fineness of the body side, unnecessary bilayer or multilayer system. fleece today for diapers and sanitary napkins used. Another object of the invention is to improve intestinal fluid control without impairing urinary control. In addition, it is an object of the present invention to achieve the passage of fluids through a perforated nonwoven without the use of surfactants, or to reduce the amount thereof to a fraction of the amount presently present in unperforated coated webs.

According to the invention, these tasks are accomplished by a perforated web of intertwined filaments having a basis weight of 7 to 25 g / m ² of intertwined interwoven filaments of microfibers with a fineness in the range of 0.05 to 0.40 dtex made of at least two thermoplastic polymers having a different hydrophobicity and having a cross-section of filaments in the form of a circular die or a hollow die cutter from which the split fibers can be released, wherein the perforations are purely shaped and free of split fibers.

The webs of the invention, despite their extremely low weight, have very high strength characteristics and, due to the low weight of the fibers, also have a very clean opening structure. Therefore, it is possible to ensure rapid passage of body fluids, especially intestinal fluids, without the addition of low surface tension surfactants (detergents) and to provide a dry cover web surface for diapers and sanitary napkins.

However, the different fibers have a titer (fineness) within the stated range. The openings, each having a surface area of 0.01 to 0.60 cm ² , are preferably spaced regularly.

The perforated web of the invention preferably has a strike-through barrier effect value after one minute below 3 seconds. The maximum tensile force in the longitudinal direction is preferably at least 30 N / 5 cm. The rewet value is preferably below 0.5 g.

For example, two different thermoplastic polymer fibers in a weight ratio in the range of 20: 80 to 80: 20 can be used to prepare the web. The following explains the production of a web of two fibers F 1 and F 2.

The invention also relates to a process for the production of such perforated webs by treating fissile filaments having a cross-section in the shape of a pie or hollow-pie in which the cross-sections contain at least two different thermoplastic polymers with different hydrophobicity in the arrangement alternating slices of the cake into a web, then splitting and entangling the fibers into entwined filaments by means of high pressure water rays and subsequently perforating the formed web with high pressure water rays.

In this case, the perforation is preferably carried out on drainage and punching drums provided with mandrels on the surface.

Next, the polymers used to produce the nonwoven fabrics of the present invention, and then the respective manufacturing processes, are mentioned first.

Of the two fiber-shaped polymers F 1 and F 2, at least one is hydrophobic and preferably belongs to polyolefins such as polyethylene, polypropylene or copolymers thereof, one of which is in excess. The second polymer may be as hydrophobic as it is hydrophilic, but it is preferred that it is not hydrophilic but less hydrophobic than polypropylene. The stronger hydrophobic polymer fiber will be referred to herein as F1 and the weaker hydrophobic as F2. The FI may preferably be of polypropylene (PP) or polyethylene (PE) or both. For example, F 2 may be a fiber from the group of polyesters such as polyethylene terephthalate, polybutylene terephthalate, polypropylene terephthalate, or a copolymer thereof with polyethylene. F 1 and F 2 are not subject to any restrictions in the choice of polymer, except that they can be coupled to bicomponent fibers in a known manner.

The fibers F1 and F2 may also be both or one of the thermoplastic elastomers. Examples of elastic polyolefins for spunbonded fiber webs can be found in EP-A-0 625 221 and for metallocene catalyzed LLDPE in EP-A-0 713 546, which also discloses representatives of weaker hydrophobic elastomers such as polyurethanes, ethylene-butylene copolymers. , poly (ethylene-butylene) -styrene (Kraton) copolymers, adipate polyester and elastomeric polyetherester (Hytrel). These elastomers are known to be spunbonded in combination with a meltblown layer or SMS. The use of such elastomers in F1 and / or F2 fibers increases the softness and flexibility of the perforated microfiber webs. Moreover, it has been shown that only perforated webs of intertwined microfibre filaments have excellent fluid control properties. Perforated webs of equally intertwined sorted microfibre fibers do not exhibit these improved properties. With regard to processing on diaper machines (high demands on tensile strength in the machine direction), their weight would have to triple on average compared to continuous filament webs, leading to a significant deterioration in perforation quality, flexibility, softness, abrasion resistance and fluid control.

It is also possible to supply additives to the polymer fiber melt in the form of parent polymer blends for the purpose of imparting antistatic properties, dyeing, matting, softening, imparting tackiness and fiber flexibility, increasing and reducing non-wettability against liquids (water, alcohols, hydrocarbons, oils) and a multidisperse system such as intestinal fluids and other liquid body secretions such as urine and menstrual blood.

The interfacial tension modifying additives on the microfiber surfaces can additionally be applied after the microfiber fibers have been formed or released in the already perforated web. Such substances are, for example, wetting agents dissolved in water or in dispersed form, which are now treated with many spunbonded nonwoven webs in diapers for better urine control.

The webs of the present invention, however, are preferably sufficient without such wetting agents, possibly with only a small fraction of the amounts usually applied so far. The perforations, i.e. the size of the holes, their shape, the arrangement of the individual holes with each other (for example in a row or with gaps) and against the open area, as well as the extremely high flexibility in the space between the interwoven micro fiber threads and their very low weight this reduction in the amount of wetting agent used up to 100% savings.

BRIEF DESCRIPTION OF THE DRAWINGS

Figures 1 to 6 complete the explanation of the invention.

1 to 6 show the shape of the individual openings K and their arrangement in plan view. In Figure 1, an aperture in the form of an equilateral hexagon is shown, in which the length of the side a is equal to b. The distance o is the shortest distance between the center c of the opening K and its edge a. The edges a and b have a constant distance g from each adjacent K. A larger equilateral hexagon with sides e and f can now be formed around the individual openings K. In Figure 1, e = f. This results in a honeycomb arrangement of the orifices K. The edges a and b of the orifice K are now parallel to the adjacent edges a and b of the adjacent orifices K. The distance h = 0.59. The vertices of the touching sides a and a and b respectively are rounded in the web. These fillets i and peaks are presented in Figure 1 for case i = j. These roundings shorten the original distances d and e in the hexagon to q and r. In the case of Figure 1, again q = r.

In the extreme case, the radiuses i and j can extend so much that the opening K becomes circular in shape, as shown in Figure 2.

The apertures to Figure 3 differ from the apertures in Figure 1 only in that b is significantly longer than a and the rounding i is more pronounced than j.

The radiuses i and j can, in extreme cases, expand so much that an elliptical shape is formed from the hexagon K, as shown in Figure 4.

The micro-fine interwoven filaments S form the frame L of the perforations. As already mentioned, the perforated web may comprise surfactants which impart a washable, delayed or permanent hydrophilic nature to it. They are conveniently applied after perforation with a water jet in a wet process. The amount applied is 0 to 0.60% by weight of the web, preferably between 0 and 0.20%. The dosage is controlled according to the area of the individual openings and the total open area. The larger the two values, the more the content of these surfactants can be reduced. For environmental reasons, a detergent content of 0% is sought.

It has proven to be particularly advantageous if the surfactant does not spread evenly over the entire frame of the opening, but is confined to the immediate vicinity of the opening edge. From there it then exerts a forced suction effect on the fluids towards the opening. Thereafter, the multi-dispersion fluid system does not dewater and phase separate. This prevents the holes from clogging and settling on them. The fluid absorbing and distributing layer positioned between the absorbent core and the cover web, which is also wetted by them, then promotes the immediate removal of body fluids from the diaper surface.

Production of perforated fleece (topsheet)

The method consists in processing the fissile fiber having a cross-sectional shape of a circular die (pie-fiber) into a filament web. The cross-sections of the uncleaved fibers exiting the nozzle consist of two different polymer components F1 and F2, which alternate sequentially as circular die cuts (normally 4 to 16 such die cuts). In the interest of downstream cleavage, it is preferable to use those (mostly two) polymeric and chemically strongly different components which exhibit as little adherence to one another as possible on the common interface. However, chemically similar polymeric components, such as polyethylene terephthalate and copolyester or polypropylene and polyethylene, may be used provided that the adherence to the bonding surfaces of both is reduced, for example by adding a separator to at least one polymeric fiber component. When such a split fiber is internally provided with a hollow and circular cross-section, we refer to a circular-sectional cross-sectional fiber of a hollow circular-sectional cross-sectional fiber.

The fineness of the filaments in the web prior to cleavage is generally 1.0 to 4.0 dtex, preferably 1.6 to 3.3 dtex. Next, the filaments of the web in the first post-processing step are intertwined with simultaneous cleavage on said cake section by known water jet pressurizing processes (see, for example, EP-A-0,215,684). Thus, in the case of fibers having a cross-section of the shape of a circular die having a fineness of 1.6 dtex with 16 segments, composed of 8 segments for each of the two polymers, microfibers with a fineness of 0.10 dtex are formed after splitting. Since the web according to the invention is a very light web, it is preferable not to use a web or a perforated substrate, but a non-perforated substrate as the substrate on which the web is laid. Thus, by reflecting water rays on this substrate, it is possible to utilize its elasticity and thereby minimize energy loss.

The perforation is followed by drying or, more preferably, prior to wet drying, a surfactant may be applied for surface hydrophilia. This is done by known methods of immersion impregnation, one-sided impregnation, painting and printing. In a particular embodiment, the surfactant is printed according to a template so that only the border regions of the fibrous frame of the holes are suppressed. This requires the production of special printing templates, which must conform to the pattern of the holes, as well as special control measures to achieve sharp contour prints on the surfactant during this operation.

DETAILED DESCRIPTION OF THE INVENTION

The hexagonal shapes of the orifices K or those which arise therefrom and their assemblies as shown in Figures 1 to 4 have proved to be particularly advantageous for fluid control. Especially in the case of openings K, in the shape of equilateral hexagons and their drains with rounded peaks, body fluid always finds the shortest way from the surface of the diaper to its interior.

However, the invention is not limited to such regular forms and arrangements. Other polygons and their rounded derivatives as well as the irregular distribution of such or other openings are conceivable for the openings K. However, such apertures and their arrangement are less suitable that the part of the excreted body fluid that is furthest from the edge of the aperture interferes in rapid outflow through aperture K. Such arrangements are shown, for example, in Figures 5 and 6.

The distance of the furthest point w to the rounded apex of the quadrilateral is significantly greater than the distance h. The ratio u / h, i.e. the maximum distance to the opening K to the minimum distance should ideally be 1/1 and in the worst case not exceed 2/1.

The area of the individual aperture ranges from 0.01 to 0.60 cm ^2, preferably from 0.04 to 0.40 cm ² . The individual holes of the perforations may all have the same shape and uniformly the same area of the perforation. However, the surface and the shape may also be different or have only a different shape or surface, provided that an u / h ratio of less than 2/1 or the same is maintained.

The open area of the openings is in the range of 8 to 40%, preferably between 12 to 35%.

Example 1

A spunbond web of 13 g / m @ ^2, consisting of 100% fiber with a cross-section of the shape of a pie-fiber with a fineness of 1.6 dtex, is deposited on a sieve. This cross-sectional fiber comprises alternately 8 propylene segments and 8 polyethylene terephthalate segments. The size of the individual polypropylene segments is selected such that the weight proportion of polypropylene is 30% and the weight proportion of polyethylene terephthalate is 70%.

The uncleaved filament web is deposited on a 100 mesh dewatering screen and compacted under 180 mbar water pressure, splitting the filament into 8 polypropylene microfibre elements and 8 polyethylene terephthalate microfibre elements.

After cleavage, the same number of polypropylene segments are now formed as from polyethylene terephthalate microfibers. The polypropylene fiber segments have a fineness of 0.06 dtex and the polyethylene terephthalate microfibre segments have a fineness of 0.14 dtex. The conversion of dtex to fiber diameter (idealized to a circular diameter) gives a value of 2.36 µm for polypropylene (density 0.91 g / cm ³ ) and a value of 4.42 µm for polyethylene terephthalate (density 1.37 g / cm 3).

After the fibers have been split with water rays, the flattened web is also perforated by high pressure water rays under a pressure of 70 kg / cm ² . In this case, drainage and perforation drums according to EP-A-0 215 684 with mandrels on the drum surface are used instead of otherwise conventional drainage screens.

After drying, a very soft sticky fleece with purely shaped openings is formed. The openings are all (idealized circular circumference and the same size. The openings are arranged in a rectangular grid with a spacing of the individual openings a, which are then overlapped by another perforated grid so that the openings overlap. spacing a = 6.0 mm The open area OF constitutes 34% of the total area.

The functional parameters of the perforated web were measured, namely the highest pulling force in the longitudinal direction according to EDANA 20.289, the barrier effect of the permeability according to EDANA 150.3 - 96 and the capacitive wetting capacity (coverstock wet back also known as rewet) according to EDANA 151.1-96.

The barrier barrier effect parameter was measured two more times after a waiting time of 1 minute without changing the filter paper layer. The measured values are now mean values from a total of 3 measurements.

The results:

Maximum tensile force in the longitudinal direction: 32.3 N / 5 cm

1. barrier effect of permeability (sec) 2. barrier effect of permeability (sec) 3. barrier effect of permeability (sec) immediately after 1 minute after another 1 minute 1.82 2.42 2.44

Rewetting: 0.09 g

Example 2

The perforated nonwoven of Example 1 was soaked in a fum by immersion in an aqueous emulsion of a non-ionic polysiloxane-based detergent. After drying, the applied amount of reagent was found to be 0.042% by weight. The following experimental results were obtained with this sample:

Maximum tensile force in the longitudinal direction: 30.2 N / 5 cm

1. barrier effect of permeability (sec) 2. barrier effect of permeability (sec) 3. barrier effect of permeability (sec) immediately after 1 minute after another 1 minute 1.58 2.10 2.11

Rewetting: 0.31 g

Comparative Example 1

A spunbonded polypropylene spunbond web of 2.2 dtex with a basis weight of 10 g / m ² bonded to a screened roller formed a spunbonded meltblown layer with a basis weight of 20 g / m ² The average microfiber diameter in the meltblown layer was 3.82 pm. The weld area of the spunbond so bonded was 5.2%.

The bilayer laminate was solidified by a pressurized water jet as described in Example 1 and subsequently perforated on a conventional 20 mesh web. An open area of 18.4% was found by calculation. This two-layer web was also very soft, but showed significant drawbacks in terms of the highest tensile strength and barrier permeability compared to the experimental values measured in Examples 1 and 2. The barrier permeability and rewet were measured on the meltblown side of the polypropylene layer.

Maximum tensile force in longitudinal direction: 25.4 N / 5 cm.

1. barrier effect of permeability (sec) 2. barrier effect of permeability (sec) 3. barrier effect of permeability (sec) immediately after 1 minute after another 1 minute 3.81 4.92 4.96

Rewetting: 0.10 g

The barrier effect values for the cover fleece are significantly too high.

Comparative Example 2

0.40% of a non-ionic polysiloxane-based humectant was applied to the sample of Comparative Example 1. Thus, as the measurement results show, it is possible to significantly reduce the barrier effect of permeability, but the rewetting value is disproportionately increased. Such high rewet values cannot be accepted for diapers,

The results:

Maximum tensile force in the longitudinal direction: 24.6 N / 5 cm

1. barrier effect of permeability (sec) 2. barrier effect of permeability (sec) 3. barrier effect of permeability (sec) immediately after 1 minute after another 1 minute 1.23 2.35 2.40

Rewet: 2.35 g

The meltblown layer gives the fleece top cover a high softness. However, in the presence of a wetting agent, this meltblown layer functions as a sponge. This construction therefore appears to be unsuitable as a covering web on the layer.

Comparative Example 3

The two-layer system described in Comparative Example 1 was subjected to a water jet treatment as in Example 1. The average radius r of the holes was perforated with a water jet r = 1.28 mm after perforation. The hole pitch was unchanged and was a = 6.0 mm.

An open area OF = 28.6% was found.

Perforated web according to one of Claims 1 to 6, characterized in that the barrier effect value is less than 3 seconds after one minute, the rewet value is less than 0.59 and the maximum tensile force in the longitudinal direction is at least 30 N / 5 cm .

A method for producing a perforated web according to any one of claims 1 to 7, characterized in that fissile continuous filaments of a cross-section of a circular segment or of a hollow circular segment are laid, the cross-section of which has at least two different thermoplastic polymers of different hydrophobicity. to form a web, the fissile fibers are then split and intertwined to intertwined microfibre fibers by high pressure water rays, and then the formed web is perforated by high pressure water rays.

Method according to claim 8, characterized in that the perforation takes place on drainage and punching drums which have mandrels on their surface.

Use of the apertured web as claimed in one of claims 1 to 7 as topsheet in sanitary articles such as diapers and sanitary napkins.

The results:

Maximum tensile force in longitudinal direction: 24.2 N / 5 cm of drawings

1. barrier effect of permeability (sec) 2. barrier effect of permeability (sec) 3. barrier effect of permeability (sec) immediately after 1 minute after another 1 minute 2.93 3.78 3.84

Rewetting: 0.10 g

Again, the barrier effect values are too high.

Claims (6)

PATENT CLAIMS Perforated web with openings (K) arranged on the surface, the web having a basis weight of 8 to 17 g / m ² , characterized in that it is made of intertwined microfibre filaments (S) with a fineness in the range 0.05 up to 0.40 dtex, which are composed of at least two thermoplastic polymers with different hydrophobicity and have a cross-section of a filament in the shape of a circular die or of a hollow circular die from which the split fibers are released, the apertures (K) being cleanly formed and free of split fibers. Perforated fleece according to claim 1, characterized in that the openings (K) are regularly arranged and the flat openings are 0.01 to 0.60 cm ² . Perforated web according to claim 1 or 2, characterized in that in the web the ratio of the maximum distance (s) of points on the web surface to the nearest aperture and their minimum distance is 1: 1 to 2: 1. Perforated web according to claims 1 to 3, characterized in that the open area of the openings represents 8 to 40% of the surface of the perforated web. Perforated web according to one of Claims 1 to 4, characterized in that it is made of polyolefin and polyester fibers in a weight ratio ranging from 20: 80 to 80: 20. 6. The perforated web of claim 1, wherein the web is impregnated with at least one surfactant in an amount that is in a ratio of 0 to 0.60% by weight of the web.