DE102018000854A1 - Fluid absorption and distribution fleece for hygiene articles - Google Patents

Abstract

The present invention describes a multi-layered liquid absorbent and absorbent nonwoven for sanitary products which has an upper surface facing the user in hygienic products and a lower surface attached to the absorbent body in sanitary products, wherein the fiber mixture of the nonwoven fabric forming the lower side has a lower having a fiber titer as the fiber blend of the nonwoven forming the top. The composite of the top with the bottom is purely thermal. The top consists of a fiber mixture of 50 to 100 weight percent melt fibers with 50 to 0 weight percent matrix fibers. The underside consists of a fiber blend of 50 to 80 weight percent absorbent fibers with 50 to 20 weight percent melt fibers.

Description

• • Erste Lage: Topsheet (Lochfolie oder Vlies)
• • Zweite Lage: Acquisition and Distribution Layer, „ADL“ ( zumeist aus Vlies)
• • Dritte Lage: Saugkern (bestehend aus Zellstoff und/oder Polyacrylsäure fixiert in einer oder mehreren Fixierlagen (SMS, ..)
• • Abschlusslage: Folie, um ein Austreten der Flüssigkeit auf der Rückseite zu unterbinden

Disposable articles for hygienic applications such as sanitary napkins, diapers and incontinence products have the purpose of removing body fluids from the skin as quickly as possible in order to avoid skin irritations and to give the user a safe and comfortable feeling. For this purpose, hygiene products are generally constructed as follows:

• • First layer: Topsheet (perforated foil or fleece)
• • Second layer: Acquisition and Distribution Layer, "ADL" (mostly made of non-woven)
• • Third layer: absorbent core (consisting of pulp and / or polyacrylic acid fixed in one or more fixing layers (SMS, ..)
• • Finishing position: Foil to prevent leakage of liquid on the back

The layers Topsheet, ADL and absorbent core must be coordinated to ensure a function in the hygiene product.
The most important role is assigned to the ADL as a transfer situation. This must absorb the liquid from the topsheet (drainage of the Topsheets), distribute the liquid in the longitudinal direction of the product and temporarily store. By caching so-called gel blocking of the polyacrylic acid powder is to be prevented. After the temporary storage, the liquid is transferred to the absorbent core for final storage.

• • Schnelle Aufnahme und Weiterleitung der Flüssigkeit
• • Zwischenspeicherung zur Pufferung der begrenzten Aufnahmegeschwindigkeit des Absorbermaterials
• • Gerichtete Verteilung der Flüssigkeit zur möglichst großflächigen Aufnahme durch das Absorbermaterial
• • Kontrollierte Abgabe der Flüssigkeit an das Absorbermaterial um lokale Verblockung und Flüssigkeitsstau zu vermeiden.

In order to achieve this goal, acquisition and distribution layers (ADL) made from nonwovens are used, which are to assume the following functions:

• • Fast recording and forwarding of the liquid
• • Buffering to buffer the limited absorption rate of the absorber material
• • Directional distribution of the liquid for the largest possible absorption by the absorber material
• • Controlled delivery of the liquid to the absorber material to avoid local blocking and fluid retention.

The most important properties of a receiving and Verteilvlieses are thus thickness, density and the resulting pore sizes and capillarity. These properties significantly influence the absorption and distribution behavior.

Depending on the product, Airlaid, Highloft and Spunlace nonwovens are used here. In the application DE 10 2012 015 219 A1 various embodiments of spunlace webs are described which have corresponding properties.

The nonwoven types described in the prior art are primarily insert structures with homogeneously distributed fiber types. Depending on the production, only one required property can be achieved. Thus, e.g. Highloft nonwovens, i. purely thermally bonded by means of melt fibers nonwovens, by their structure, a high thickness and a good fluid absorption associated therewith. Due to the comparatively high porosity but the distribution effect is very low. As a result, only a very limited use of the underlying absorbent core is possible.

The nonwovens produced by the airlaid process have a good distribution effect through the fine capillaries. Due to the high proportion of pulp but the thickness is low and the liquid is released back to the surface, resulting in a high Rewet result.

Zweilagenaufbauten that come from a one- or two-stage manufacturing process, such as in the DE102016005158 , are also not effective. The compound of the layers is done by means of water jets, so that, for example. Hydrophilizing be washed off, so that the liquid absorption is insufficient. Furthermore, the resulting final thickness is insufficient because of the type of solidification, since especially the ADL side can absorb only a small amount of liquid.

Although a connection of the layers in multilayer constructions by means of adhesive, such as, for example, by means of hotmelt via spray coating or slotcoating, results in a sufficient layer adhesion, however, the Hotmelt makes the liquid transfer difficult. It forms at the transitions of the layers with hotmelt blocked areas that are liquid impermeable.

Prior art materials combine the properties of liquid distribution and liquid absorption, with a reduction in the respective effect to be accepted.

The object of the present invention is therefore to provide a material which avoids the disadvantages of the prior art mentioned and has an improved liquid absorption with simultaneous given liquid distribution.

The problem is solved by the features mentioned in claim 1, meaningful embodiments can be found in claims 2 to 6.

This is achieved in that the nonwoven fabric in its vertical structure, ie perpendicular to the layer plane, wherein the top and the bottom is made with different fiber composition and optionally also different Verfestigungsart. Thereby, each side can be formed so that the respective function is optimally fulfilled by the fiber mixture and / or the hardening.

According to the invention, the bonding of the layers takes place exclusively thermally, the fiber mixture of the upper side having a proportion of more than 50% by weight of melt fibers. So it is guaranteed to form a sufficient number of binding points of the top with the bottom.

The transition of the zones also creates a gradient of physical properties, so that the upper side has the greatest permeability and mechanical stability, while the lower side facing the absorbent core has the greatest capillarity. Due to the gradient, the liquid is transported quickly and almost completely away from the body side and forced by physical forces to the absorbent core.

The following are some of the terms used in the following description:

Textile fibers have so-called "lubricants" on the fiber surface to improve the processing properties but also to ensure certain effects in the finished product.

A "suction fiber" in the sense of the present invention is a regenerated cellulose fiber which is produced from solutions of cellulose derivatives. This viscose fiber may have a modification of the surface, e.g. trilobal cross-section, but also be modified so that a moderate fluid intake is promoted with good fluid storage at the same time. Representatives of the invention are, for example, Viscostar viscose fibers or normal viscose fibers of the manufacturer Lenzing, but also the so-called Galaxy fiber from Kehlheim Fibers. In particular, viscose fibers which are produced by the Lyocell process (Tencel Fa. Lenzing) can also be used. Typical fiber finenesses are in the range of 1.0 to 3.3 dtex, preferably 1.3 to 2.2 dtex. If staple fibers are used, the fiber lengths used range from 10 to 70 mm, preferably from 35 to 50 mm. The absorbent fibers have commercial ripples. The term absorbent fiber can also refer to short fibers or pulp should the underside be an airlaid.

For the purposes of the present invention, the term "matrix fiber" is used for staple fibers of thermoplastic and / or thermosetting polymers contained in the top. Preference is given to fibers of thermoplastic polymers such as polyester or polypropylene. The melting temperature must be at least 10 ° C above the used melt fibers. However, thermosetting polymers such as polyacrylic fibers are also suitable. The fiber finenesses are in the range of 3.3 to 17 dtex, preferably 4.4 to 10.0 dtex; the fiber lengths used are in the range of 10 to 80 mm, preferably 35 to 60 mm. The distribution fibers have commercial 2D or 3D ripples.

The terms "finishing" or "finishing" designate a functional finish on fiber surfaces. These lubricants are used commercially as processing aids, i. Treat fibers in such a way that static charge is prevented, especially with PP or PE fibers. Avivages are usually used on the surface of staple fibers. The type of finishes chosen can influence the hydrophilicity or hydrophobicity, which can have a great influence on the properties of the liquid absorption and release fleece. The coatings are present on both the surfaces of the melt fibers, as well as on the matrix fibers and the absorbent fibers.

• • den Verbund der Oberseite mit der Unterseite den Faserverbund ermöglichen
• • die Struktur der Oberseite stabilisieren, sodass ein weitestgehend dimensionsstabiles Vlies entsteht.

"Melt fibers" in the sense of the present invention are fibers which are present in a product constructed according to the invention

• • allow the composite of the top with the bottom of the fiber composite
• • stabilize the structure of the top so that a largely dimensionally stable fleece is formed.

Melt fibers are homo- or bicomponent thermoplastic polymer fibers having fusible fractions. When exposed to temperature, these proportions melt and stabilize after cooling the fiber composite. According to the invention suitable fibers are homopolymer staple fibers of co-polyester, co-polyamide or polypropylene, according to the invention are preferred bicomponent melt fibers in core-sheath or side-by-side arrangement of combinations of low melting co-polyester with polyester, polyethylene with polypropylene or polyethylene with polyester , The fiber finenesses for the melt fibers used in the top are in the range of 2.2 to 12 dtex, preferably 4.4 to 6.7 dtex; the fiber lengths used are in the range of 10 to 80 mm, preferably 35 to 60 mm.

The fiber finenesses for the melt fibers used in the underside are in the range of 1.7 to 3.3 dtex, preferably 1.7 to 2.2 dtex; the fiber lengths used, when using staple fibers in the range of 10 - 80mm, preferably 35-60mm, when using short fibers, the bottom should be formed by an airlaid nonwoven, between 1 to 5mm, preferably 3mm. If the melt fibers are carded staple fibers, they exhibit commercial crimping.

Nonwovens according to the invention are prepared by means of a dry or wet process, the underlying processes can be taken from the book "Nonwovens" published in 2000 by Wiley VCH Verlag, Weinheim. Specifically, the nonwoven fabric forming the underside may be an airlaid nonwoven fabric, a so-called "airlaid". Carded staple fiber nonwoven fabrics are preferred according to the invention.

The fibers used are homogeneously mixed together in the production of a fiber mixture. The basic techniques are also shown in the book "Nonwovens".

According to the invention, the "upper side" is the page which, in the hygiene product, is turned towards the user and hits the liquid first.

The "bottom" is the side of the nonwoven fabric according to the invention, which is mounted in the hygiene product to the absorbent body.

"Precursor" refers to a prefabricated nonwoven which has already undergone the process steps of fiber mixing, web formation and nonwoven bonding. According to the invention, the underside is formed by a precursor.

The following examples are, but are not limited to, staple fiber nonwoven fabric made by dry processes using the carding process.

• • Flächengewicht gemäß WSP 130.1., Angabe in kg/m²
• • Dicke gemäß WSP 120.6, Abschnitt 7.2, Messdruck 0,5kPa, Angabe in m
• • Trennfestigkeit gemäß NWSP401.0.R0(15), Angabe in N
• • Dicke der Oberseite wird gemäß folgender Formel ermittelt: $$\text{Dicke Oberseite }\left(\text{m}\right)=\text{Gesamtdicke }\left(\text{m}\right)-\text{Dicke Precursor }\left(\text{m}\right)$$
  
• • Dichte gemäß folgender Formel: $$\text{Dichte }\left({\text{kg/m}}^{\text{3}}\right)=\frac{\text{Flächengewicht }\left({\text{kg/m}}^{\text{2}}\right)}{\text{Trockendicke }\left(\text{m}\right)}$$
  
• • Strike Through gemäß WSP 70.3, Angabe in s
• • Rewet gemäß WSP 80.10, Angabe in g
• • Mittlerer Fasertiter innerhalb einer Lage: errechnet sich nach folgender Formel $$\text{Mittlerer Fasertiter }\left(\text{dtex}\right)=\frac{\text{A*Titer 1}+\text{B*Titel 2}+\text{C*Titer 3}}{\text{100}}$$
  
  • A,B,C = Prozentanteil einer Faserkomponente in der Mischung, wobei die Summe aus A, B, und C = 100 ist.
  • Titer 1,2,3 = nominaler Titer der jeweiligen Faserkomponente in dtex

In addition, Table 1 shows the test results obtained. The determined parameters were determined according to the following test methods:

• • Basis weight according to WSP 130.1., In kg / m ²
• • Thickness according to WSP 120.6, section 7.2, measuring pressure 0,5kPa, indicated in m
• • Breaking strength according to NWSP401.0.R0 (15), specified in N
• • Thickness of the top is determined according to the following formula: $$\text{Thick top}\left(\text{m}\right)=\text{total thickness}\left(\text{m}\right)-\text{Thick precursor}\left(\text{m}\right)$$
  
• Density according to the following formula: $$\text{density}\left({\text{kg / m}}^{\text{3}}\right)=\frac{\text{grammage}\left({\text{kg / m}}^{\text{2}}\right)}{\text{dry thickness}\left(\text{m}\right)}$$
  
• • Strike through according to WSP 70.3, specified in s
• • Rewet according to WSP 80.10, in g
• • Average fiber titer within one layer: calculated using the following formula $$\text{Average fiber titer}\left(\text{dtex}\right)=\frac{\text{A * titer 1}+\text{B * Title 2}+\text{C * titer 3}}{\text{100}}$$
  
  • A, B, C = percentage of a fiber component in the mixture, the sum of A, B, and C = 100.
  • Titer 1,2,3 = nominal titer of the respective fiber component in dtex

The required properties, i. Fast fluid absorption, good distribution with temporary caching and forwarding to the absorbent core are achieved according to the invention by a structure of two nonwoven layers bonded together.

• • Herstellen einer Fasermischung für den Precursor, bestehend aus Saugfaser unter Zumischung von Schmelzfaser
• • Herstellen einer unverfestigten Materialbahn aus der Fasermischung des Precursors
• • Thermisches und/oder mechanisches Verfestigen der Materialbahn, sodass der Precursor mit einer Dichte von 50 bis 200 kg/m³ und einer Dicke von 0,4 bis 1,0mm entsteht.
• • Optional: Aufwickeln des Precursors
• • Herstellen einer Fasermischung für die Oberseite, bestehend aus Matrixfaser und Schmelzfaser
• • Herstellen einer unverfestigten Materialbahn aus der Fasermischung der Oberseite
• • Ablegen der unverfestigten Materialbahn auf dem Precursor
• • Verfestigung der Oberseite und Verbindung der Oberseite mit dem Precursor mittels einer Heißluft-Behandlung.
• • Optional: Zusätzliche Passage eines Kalanders zur Stabilisierung des Verbundes. Die Verfestigungsfläche soll weniger als 10%, bevorzugt weniger als 7% betragen.
• • Wickeln des erfindungsgemäßen Flüssigkeitsaufnahme- und Verteilvlieses

A liquid receiving and distribution web produced according to the invention runs through the following process steps:

• • producing a fiber mixture for the precursor, consisting of absorbent fiber with admixture of melt fiber
• • Producing an unconsolidated material web from the fiber mixture of the precursor
• Thermal and / or mechanical strengthening of the material web so that the precursor is produced with a density of 50 to 200 kg / m ³ and a thickness of 0.4 to 1.0 mm.
• • Optional: winding the precursor
• • Making a fiber blend for the top, consisting of matrix fiber and melt fiber
• • producing an unconsolidated material web from the fiber mixture of the upper side
• • Laying the unconsolidated material web on the precursor
• • Solidification of the top and connection of the top with the precursor by means of a hot air treatment.
• • Optional: Additional passage of a calender to stabilize the composite. The solidification surface should be less than 10%, preferably less than 7%.
• • winding the liquid receiving and Verteilvlieses invention

According to the invention, the nonwoven fabric forming the underside consists of a precursor which has a content of 50 to 100% by mass of absorbent fiber. In the precursor fiber blends are used, which have a difference of the middle fiber titer of precursor to the top. According to the invention, the difference must be at least 2dtex, the mean fiber titer of the fiber mixture of the precursor having to be lower than that of the top side.

The average fiber titer of the fiber mixture of the precursor is in the range from 1.0 to 6.0 dtex, with this preferably being less than 4 dtex and most preferably less than 2.0 dtex.

If the production of the precursor, as preferred according to the invention, takes place as a carded staple fiber fleece, a fiber orientation results in the production direction of the nonwoven fabric. This orientation is advantageous for later use, since the fiber orientation then also runs in the longitudinal direction of the finished hygiene product. This improves the utilization of the available suction surface in the hygiene product.

In the solidification of the precursor, which is preferred according to the invention, but without being limited by means of water jets, the precursor is densified at the same time, so that the density of the precursor is higher than that of the final receiving and distribution nonwoven fabric. Densities of the precursor of 50 to 200 kg / m ³ , preferably 80 to 120 kg / m ³ , are provided, the thickness range of the precursor being between 0.4 and 1 mm and a basis weight of 0.025 to 0.120 kg / m 2 being sought.

Due to the selected average fiber titer of the precursor in conjunction with the compression during the solidification of the precursor, the capillary action and thus the ability to transport liquid within the precursor is positively influenced.

According to the invention, an unconsolidated, carded fiber pile is now deposited on this precursor. This batt forms after a subsequent solidification and bonding step, the top of the nonwoven fabric according to the invention.

The solidification of the fibrous web of the upper side and the composite of the upper side with the precursor takes place according to the invention by means of thermal treatment, that is to say by means of hot air solidification and optionally subsequent calender consolidation. The basic techniques can be found in the book "Nonwovens", published by Wiley-VCH in 2012 on pages 375-395.

The batt of the top consists of 50 to 0 percent by weight of matrix fibers and 50 to 100 percent by mass of melt fibers.

According to the invention, a proportion of more than 50% melt fibers is necessary in the fiber mixture which forms the upper side. This proportion is significant in comparison to the prior art and ensures a sufficient number of possible binding points between the top and the bottom.

If one places the unconsolidated fiber pile, which forms the upper side after solidification, on the underside, there are only a few points of contact at the boundary layer between the upper and lower sides, which can merge after hot air treatment or can form bonding points.

Necessary and preferred according to the invention, but without being limited thereto, it is therefore necessary to provide a system for hot-air hardening which operates on the flow-through principle. Hot air hits the initially unconsolidated fiber pile of the upper side and flows through the upper side followed by the lower side. Depending on the amount of hot air flowing through and the flow rate of the fibrous web of the top undergoes less or greater compression compared to the thickness of the unconsolidated Faserflores.

By means of this compaction forms on the boundary layer top to bottom a significantly larger number of contact points and therefore possible binding points of melt fibers compared to the simple "laying" of the batt and solidification by spraying or radiant heat.

To ensure adhesion of the top to the bottom, melt fibers are used in the fiber blend of the bottom. This is because the connection between fused fibers is facilitated and such bonding points of fused fibers from the top to the bottom are more mechanically stable.

Particularly advantageous is the hot air solidification and compound has shown in relation to the Avivierung the fibers of the top. If a composite is produced by means of water-jet turbulence, the lubricant present on the fibers is almost completely washed off by the water jets. Fiber or nonwoven properties achieved with Avivage are thereby changed so that requirement profiles can not be met. The hot air hardening and bonding process preserves the finishes on the fiber surfaces and does not affect their properties.

For the precursor, the upper limit for the content of fused fiber is 50% by weight, since fractions greater than 50% by weight suffer from liquid storage and, on the other hand, the precursor becomes too stiff.

Likewise preferred according to the invention are also similar melt fibers, i. be used from the same polymers, so that the adhesion is improved from top to bottom.

In another preferred embodiment, in particular for the case that exclusively absorbent fibers are contained in the precursor, a type of melt fiber can be used which has a particular affinity for cellulosic polymers.

The average denier of the fiber mixture of the upper side is greater than 3.3 dtex, preferably in the range of 4.4 to 12 dtex and more preferably in the range of 6.7 to 12dtex. Due to this average fiber titer, the fleece forming the upper side is open enough to absorb liquid quickly and to be forwarded to the To save the bottom between. The higher the average fiber diameter of the mixture, the better the resistance of the upper side to compressive loads. With increasing proportions of melt fibers, the top also becomes more mechanically stable, ie, has improved resistance to compression, such as high packing density of diapers or punctiform loads in use.

The Rewet is positively influenced by higher average fiber titers and with a melt fiber content greater than 75% by weight.

By a thermal activation of the melt fibers in particular the stability of the upper side is ensured. This ensures improved resistance to the already mentioned compression in the product application.

According to the invention, the solidification conditions in combination with the fiber mixture of the upper side are selected such that the liquid absorbent and distribution nonwoven according to the invention has a thickness of greater than 3 mm, preferably greater than 5 mm.

In the case where the content of the fused fiber is less than 30% by weight in the fiber mixture constituting the lower surface, optional thermal calendering treatment may be provided to improve adhesion from the top to the bottom. The adhesion is determined by the separation strength.

In order not to influence the thickness of the liquid receiving and Verteilvlieses, it is therefore to choose the arrangement of the calender and the calender engraving accordingly.

The gravure roll must be arranged so that the embossing is on the top. On the one hand, the engraved roll must have a pressing surface of less than 10%, preferably less than 7%, and on the other hand the web height, ie the distance from engraving base to pressing plateau, must be greater than 2 mm. Engravings are used according to the invention, which, if not formed as lines, have less than 10 engraving points per cm ² , particularly preferred are engravings with 7 or fewer engraving points per cm ² .

To ensure liquid absorption in the upper side, the liquid absorption and distribution fleece according to the invention has an open, mechanically stable nonwoven structure and, for distribution, a compressed underside for absorbing liquids and distributing them due to capillarity.

• • Mittleren Titer der Fasermischung > 4,0 dtex
• • Dicke der Oberseite > 0,002m
• • Gewicht der Oberseite > 0,04kg/m²

The requirements for the top are achieved by:

• • Average titer of the fiber blend> 4.0 dtex
• • Thickness of the upper side> 0,002m
• • Weight of the upper side> 0.04kg / m ²

• • Mittleren Titer der Fasermischung <6,0dtex
• • Dicke der Unterseite < 0,001 m
• • Gewicht der Unterseite < 0,06kg/m²

The requirements for the underside are achieved by:

• • Average titer of the fiber blend <6.0 dtex
• • Thickness of the underside <0,001 m
• • Weight of the bottom <0.06kg / m ²

• • Anteil der Schmelzfasern > 50 Gewichtsprozent in der Fasermischung der Oberseite
• • Anteil der Schmelzfasern von 20- 50 Gewichtsprozent in der Fasermischung der Unterseite
• • Anwendung von Heißluftbehandlung mit Luftströmung von Oberseite durch Unterseite.
• • Optionale Anwendung einer nach der Heißluftbehandlung sich anschließenden Kalanderbehandlung.

The requirements for the connection of top side and bottom side, wherein the thickness of the top side is not significantly affected, are achieved by the provision of

• • proportion of melt fibers> 50 weight percent in the fiber blend of the top
• • Proportion of fusing fibers of 20-50% by weight in the fiber blend of the underside
• • Application of hot air treatment with air flow from top through bottom.
• • Optional application of a calender treatment following the hot air treatment.

• • Die Dicke der Oberseite hat einen Anteil von mindestens 60% der Gesamtdicke
• • Die Dichte der Unterseite ist mindestens doppelt so hoch wie die Dichte der Oberseite
• • Der mittlere Fasertiter der Oberseite muss mindestens 2,0dtex größer sein als der mittlere Fasertiter der Unterseite.
• • Die Dichte des Flüssigkeitsaufnahme- und Verteilvlies beträgt maximal 35kg/m³

In the combination of the features of the upper side with the lower side, it follows that a liquid absorption and distribution nonwoven according to the invention has the following features:

• • The thickness of the top has a share of at least 60% of the total thickness
• • The density of the bottom is at least twice as high as the density of the top
• • The average fiber titer on the upper side must be at least 2.0dtex larger than the average fiber titer on the underside.
• • The density of the liquid absorption and distribution fleece is a maximum of 35kg / m ³

Looking at Table 1, one can see the following:

The pattern 1 represents one according to DE102016005158 manufactured, attributable to the prior art liquid receiving and Verteilvlies. The composite of the top with the bottom is done by means of water jets.
Although the average fiber titer is 6.2dtex at the top and the average fiber titer at the bottom is 2.2 dtex, the thickness is 0.00178m due to the compression of the water jets. The strike-through is 9.4s.

Samples 2 through 5 were treated by hot air solidification in a belt dryer. For the underside, a nonwoven already solidified by means of water jets was used as the precursor. Then, according to the invention, the unconsolidated fiber pile was placed on this nonwoven forming the underside and the fiber pile was solidified so that the upper side had formed. The composite top to bottom happened by means of the directed air conduction of the hot air from the top towards the bottom. The drying temperatures used depend on the type of polymers and melt viscosity. For samples 2 through 5, temperatures ranging from 120 to 140 ° C were used without limitation.

Considering the inventively executed pattern 2, which was prepared with identical fiber mixtures of the top according to the pattern 1, wherein the connection of upper side with underside according to the invention by means of hot air on a flat belt dryer happened, it can be seen that the total thickness by a factor of 3 higher compared to the pattern 1 lies. Due to the lower compression of the upper side and also the presence of hydrophilic coating on all fibers of the upper side results in an improved compared to the prior art Strike Through. The separation strength is at an acceptable level, ie during processing, the connection is maintained from top to bottom. The difference between the middle fiber titer from top to bottom is 4.5 dtex. The pattern 1 has the same difference in titer, but the top has a significantly smaller thickness compared to the top of the pattern 2.
By using very high denier matrix fibers, ie 10dtex, the high thickness of the top of pattern 2 is ensured. This ensures a very high porosity. The density of the pattern 2 according to the invention at 17 kg / m ³ , this is compared to the pattern 1 by 3.8 lower.

In the case of the sample 3 produced according to the invention, the use of matrix fibers is dispensed with. The proportion of fused fibers is 100% by weight. Due to the difference between the middle fiber titer of the mixture top to bottom side of 3.1dtex, the porosity of the top again arises. Because of the melt fiber content of 100 weight percent, the release strength is at a higher level compared to Sample 2. The difference of the middle fiber titre from top to bottom is 3.1 dtex for Sample 3. StrikeThrough and also Rewet are in an area that matches Pattern 2. The density at 29kg / m ³ , which is almost twice as high compared to sample 2. This higher density requires a slightly higher intake.

Pattern 4 envisages the use of only 20% by weight of fused fibers in the bottom compared to Samples 2 and 3. The ply adhesion is therefore significantly lower compared to patterns 2 and 3, so that this proportion of melt fibers in the bottom defines the lower limit.

In Sample 5, a calendering treatment following hot air hardening was carried out. In this case, a calender engraving was used, which has a pressing surface of 5% and 9 figures / cm ² at a web height of 2mm. The pressure was 75daN / cm, the roller temperature 125 ° C. The gravure roll presses on the top.

In addition to a positive influence on the ply adhesion, there is also a slight increase in the capillary action on the surface of the upper side. This promotes directional fluid transfer.

Looking at the pattern 5, wherein the average fiber titer of the upper side is 4.4 dtex, a higher density is exhibited compared to the inventively executed patterns 2 to 4, but the StrikeThrough and also the Rewet are in the range of the pattern 2 to 4 ,

In other embodiments of the invention can also calender engraving in the form of lines similar to DE10103627 be used. Again, it should be noted that the web height of 2mm and higher and also the pressing surface is less than 10%.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102012015219 A1 [0005]
• DE 102016005158 [0008, 0063]
• DE 10103627 [0071]

Claims (6)

A multi-layered liquid absorbent and dispensing nonwoven fabric for sanitary products which has an upper surface facing the user in hygienic products and a lower surface which is attached to the absorbent body in sanitary products, the fiber mixture of the lower nonwoven fabric having a lower average fiber titer than that A fiber mixture of the nonwoven fabric forming the upper side, characterized in that - the top consists of a nonwoven fabric and the fiber mixture consists of 50 to 100 weight percent melt fibers and 50 to 0 weight percent matrix fibers, - the underside consists of a nonwoven fabric and its fiber blend of 50 to 80 weight percent Absorbent fibers and 50 to 20 percent by weight of fused fibers, - the upper side is exclusively thermally fusion bonded to the underside and - the density of the liquid absorption and distribution fleece is 35 kg / m ³ or less. Multi-layer fluid intake and distribution fleece after Claim 1 characterized in that - the average fiber titer of the fiber mixture of the nonwoven fabric forming the lower side is at least 2dtex lower than the average fiber titer of the fiber mixture of the nonwoven fabric forming the upper side. Multilayer liquid absorption and distribution fleece according to one of the preceding claims, characterized in that - the upper side is thermally fusion bonded to the underside by a hot air treatment or - the upper side is thermally fusion bonded to the underside by a hot air treatment and with a subsequent calendering treatment. Multi-layer liquid absorption and distribution fleece according to one of the preceding claims, characterized in that - the thickness of the top has a proportion of at least 60% of the total thickness Multilayer liquid absorption and distribution fleece according to one of the preceding claims, characterized in that - the melt component of the melt fibers in the top and the bottom of the same polymers. Multi-layer fluid intake and distribution fleece according to one of the preceding claims, characterized in that - the density of the bottom is at least twice as high as the density of the top