DE20118532U1 - Composite material for the management of body fluids - Google Patents

Description

E17/2001/ROI

Christian Heinrich Sandler GmbH & Co KG
Lamitzmühle 1

95126 Schwarzenbach

Composite material for the management of body fluids Description

The development in the area of hygiene products, namely diapers, panty liners, but also products for the incontinence area, makes it necessary to use fluid management layers that are precisely tailored to this purpose for repeated, rapid fluid absorption, transfer and storage.

Commercially available hygiene products have the following schematic structure:

- Cover layer facing the user made of fleece and/or film Liquid distribution layer made of, for example, a carded fleece

- Liquid storage layer made of, for example, a meltblown fleece

- Laundry protection layer made of fleece or foil facing away from the user

The function of the fluid distribution layer is the rapid absorption of excreted body fluids, as well as the targeted distribution and forwarding to the downstream absorption/storage layer.

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This function is often achieved by combining open structures in the area of the liquid distribution layer made of, for example, carded, coarse-denier fiber fleece with good resistance to compression and a downstream liquid storage layer made of, for example,

meltblown nonwoven fabric.

In this combination of, for example, carded and meltblown nonwoven fabric, both layers must be connected to each other in such a way that, on the one hand, processing reliability is guaranteed and, on the other hand, this has a positive effect on the actual function, the absorption of liquid and its transmission and storage.

Although there are various methods available at the state of the art to achieve a bond that is safe to process and secure against displacement, this has resulted in further unacceptable disadvantages of the end product.

For example, US 5591149 discloses a connection created by means of pressure and heat in a calender. This type of connection uses the special design of the calender print, but has significant disadvantages with regard to the choice of material and the thickness of the structure.

Starting materials with very different melting points, such as polyethylene and polyester, are difficult to bond using this method. Furthermore, the thickness of the composite is also greatly reduced during the bonding process, so that a significant part of the coarse structure in the liquid absorption zone is inactivated and ultimately the function deteriorates.

The teaching of DE 199 277 85 shows a mechanical entanglement of fibers of a meltblown nonwoven fabric with the open structure of a carded nonwoven fabric.

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This is achieved by short meltblown fibers that work their way into the open structure of the carded fleece. Since this is only a mechanical entanglement, the adhesion between the layers is correspondingly low. In addition, it was shown that the liquid transport effect between these layers is inadequate due to the short fibers.

A multi-layer structure in which the bond is achieved by means of an adhesive does indeed provide excellent layer adhesion, but the adhesive acts as a separating layer, so the liquid distribution effect is too low.

The invention was therefore based on the object of providing a multilayer composite material, while avoiding the aforementioned disadvantages, which has an undamaged coarse-structured liquid distribution layer and an undamaged fine-structured liquid storage layer, has no distribution-inhibiting boundary layer and nevertheless has optimal layer adhesion.

The object was achieved according to the features of claim 1, advantageous embodiments are mentioned in the subclaims 2 to 16.

Figure 1 shows the composite material (4) designed according to the invention, consisting of a liquid distribution layer (2), which consists for example of a carded fleece containing staple fibers (6), and the liquid storage layer (3), which consists for example of a fleece containing meltblown fibers (8) and multifilament fiber strands (5).

Figure 2 shows the use of the composite material (4) according to the invention using a cross-sectional drawing.

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The connection of the liquid distribution layer (2) and the liquid storage layer (3) is achieved during the manufacture of the liquid storage layer (3).

A base fleece, which later forms the liquid distribution layer (2) in the composite, is used as a carrier material.

The liquid storage layer (3) is formed by the melt-blowing process, with the process settings being selected according to the information in Table 1. The carrier material is guided over the collector drum so that the melt-blown fibers (8 in Figure 7) of the liquid storage layer (3) collect on the carrier material and bond to it according to the invention.

Open-structured staple fiber nonwovens have proven to be advantageous. A small bonding area in the range of 5 to 15% is particularly advantageous for thermally calender-bonded nonwovens. Alternatively, hydrodynamically bonded staple fiber nonwovens or thermally, hot-air bonded staple fiber nonwovens can also be used.

The process setting on the melt blowing unit must be selected so that, in addition to individual microfibers, clumps of these, so-called multifilament fiber strands, are formed. The choice of air conditions at the nozzle tip of the melt blowing unit generates turbulence, which results in clumps of just-produced melt blown fibers (8 in Figure 7). A suitable method for producing such nonwovens is disclosed in DE 199 53 717 A1.

These multifilament, melt-blown fiber strands (5 in Figure 7) have, due to the agglomeration of several individual fibers into a conglomerate, a higher energy density than the fibers obtained using the above-mentioned method (8 in Figure 7). This means that these fiber strands (5 in Figure 7)

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When they hit the base fleece they are still largely molten and therefore literally flow around staple fibres (6 in Figure 7) protruding from the base fleece.

After cooling, force- and form-fitting anchoring points (1) of the multifilament fiber strands (5 in Figure 7) of the meltblown nonwoven fabric with the staple fibers (6 in Figure 7) of the base nonwoven fabric are created.

The force-fitting connection of the multifilament fiber strands (5 in Figure 7) with the staple fibers (6 in Figure 7) at the anchoring points (1) on the one hand causes the mechanically stable connection of the liquid distribution layer (2) with the liquid storage layer (3), on the other hand it also enables the boundary layer-free liquid transfer from the liquid distribution layer (2) to the liquid storage layer (3) in the form of liquid conducting strands thus formed (7 in Figure 7).

The fact that these liquid conducting strands (7 in Figure 7) are physically, three-dimensionally anchored in both the liquid distribution layer (2) and the liquid storage layer (3) represents a boundary layer-free connection between the two liquid distribution layers (2) and liquid storage layer (3), whereby the liquid conducting strands (7 in Figure 7) develop a wicking effect due to their capillarity.

Figure 7 shows an SEM image of the composite material (4) in cross-section, whereby the formation of the anchoring points (1) between the two liquid distribution layers (2) and liquid storage layers (3) is clearly visible.

Figure 8 shows an SEM image of an anchoring point (1) of a multifilament meltblown fiber strand (5) contained in the liquid storage layer (3) with staple fibers (6) protruding from the liquid distribution layer (2).

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A suitable process setting for obtaining a composite material (4) according to the invention is shown in Table 1 below.

Table 1: Process parameters for the example

Volume flow V1 [ft ³ /min] 280 Volume flow V2 [fP/min] 350 Nozzle tip temperature [ ⁰ C] 290 granules 100% Polypropylene HH 442H Basell Ratio V1/V2 0.8 Exit angle &agr; approx. 47° Storage medium Collector drum Position of the storage medium Zenith under nozzle opening Pull direction in the opening direction of the trigger angle &agr; Fiber curl Yes Fiber diameter of meltblown
Nonwoven fabric from-to 2 to approx. 47 pm Basis mass of meltblown
Nonwoven fabric 80g/ ^m2 Base fleece Carded, thermal-calendered
consolidated staple fiber fleece made of 100%
PES fiber 6.7 dtex/40mm, 25 g/sqm

The following Table 2 describes the different properties of the composite material in comparison to the state of the art.

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Table 2: Comparison of various properties of the composite material according to the invention with the prior art

product Weight
(g/sqm) thickness
(mm) Layers
liability
(N/5cm) Intake
time
(lake/
20ml) Back-
wetting
(G/
20ml) Fluid distribution effect
(Propagation
diameter in mm) after
120
lake after
240 sea Adhesive bond 110 1.32 1.35 36.4 12.20 after
60 sea 42 58 Calender compound 104 0.86 1.21 26.5 8.61 20 52 64 Overblow after
the status of
Technology 100 1.55 0.17 17.4 3.87 36 75 94 Invention
appropriate
Composite material
(4) 105 1.76 0.80 14.8 2.57 57 95 119 56

The composition of the materials used is as follows:

Adhesive composite: Liquid absorption layer made of carded fleece (25 g/m²) made of 100% PES fiber, 6.7 dtex, bonded to a liquid storage layer made of a PP meltblown fleece (80 g/m²) using 3 g/m² hot melt adhesive.

Calender composite: Liquid absorption layer made of carded fleece (25 g/m²) made of 100% PP fiber, 6.7 dtex, thermally bonded to a liquid storage layer made of a PP meltblown fleece (80 g/m²).

State-of-the-art overblow: liquid absorption layer made of carded fleece (25 g/m²) made of 100% PES fiber, 6.7 dtex, combined with a liquid storage layer made of a PP meltblown fleece (75 g/m²).

Inventive wet composite material (4): Liquid distribution layer (2) made of carded fleece (25 g/m²) made of 100% PES staple fiber (6), 6.7 dtex, with a

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• · · · • · t t

Liquid storage layer (3) made of a PP meltblown nonwoven fabric (80 g/m²)
tied together.

The following test methods were used:

Weight: according to EDANA 40.3 - 99

Thickness: according to EDANA 30.5 - 99, measuring pressure 0.02 kPa

Layer adhesion: according to DIN 53539

Suction time: according to EDANA 150.4 - 99, with 20 ml test liquid

Rewetting: according to EDANA 151.2 - 99, with 20 ml test fluid

Fluid distribution effect: spreading of a fluid quantity of 20 ml 0.9%
NaCI solution within the liquid storage layer (3), indication of
Diameter of the liquid-permeated area according to different
Exposure times in mm.

From Table 2 it can be seen that the composite materials (4) produced according to the invention are far superior to the conventional liquid transport layers corresponding to the state of the art, both in terms of absorption time and in terms of their distribution effect.

It can be seen that, for comparable basis weights, the absorption time of the composite material (4) according to the invention is up to 50 percent lower than that of conventional products.

This also applies to rewetting. This shows the negative influence of barrier effects in, for example, adhesive-based composites, which have up to six times higher rewetting than composite materials produced according to the invention (4).

The fluid distribution effect, a measure of the efficiency of fluid management, is also significantly superior to that of the state of the art.

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Liquid quantities are distributed over an area of the liquid storage layer (3) that is up to 5 times larger than is the case with state-of-the-art materials.

This shows the positive interaction of the boundary layer-free composite and the liquid conducting strands (7) produced according to the invention, so that an uninhibited fluid transport from the liquid distribution layer (2) to the liquid storage layer (3), as well as within the liquid storage layer (3) can take place.

A return transport of already stored liquid, also referred to as rewetting, is avoided due to the decreasing fiber titre from the liquid distribution layer (2) to the liquid storage layer (3) and the resulting increasing capillary effect.

Figures 3-6 also illustrate the liquid distribution effect over time. Here, the spread of 20 ml of 0.9% NaCl solution colored with food coloring can be observed.

In Figure 3, the liquid is initially received in the liquid distribution layer (2) and is then passed on to the liquid storage layer (3) in Figures 4 and 5. However, the liquid transport takes place not only in the vertical direction due to the liquid guide strands (7) designed according to the invention, but simultaneously also along the liquid guide strands (flGUR7) in a quasi-horizontal direction, so that the liquid storage layer (3) is used more efficiently, up to the point of completely relieving the liquid distribution layer (2) (see Figure 6).

When using the composite material (4) according to the invention, it is also irrelevant what the melting point difference of the base materials used is, since ultimately only the polymer has to be melted to produce the meltblown nonwoven fabric.

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• · ♦ ·

Composite materials (4) produced according to the invention are therefore suitable as universally applicable fluid management components in a wide variety of hygiene products; they can therefore be used in the feminine hygiene sector, diaper sector, but also in the incontinence sector.

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List of reference symbols for E 17/01 ..Composite material for the management of Body fluids"

1 - Anchor point

2 - Liquid distribution layer

3 - Liquid storage layer

4 - Composite material

5 - Multifilament fiber strands

6 - Staple fibres

7 - Fluid guide line

8 - Fibers

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Claims (16)

1. Composite material ( 4 ) for the management of body fluids made of at least two fibrous material layers, consisting of an adhesive-free connection of a fluid storage layer ( 3 ) with a fluid distribution layer ( 2 ) containing staple fibers ( 6 ), characterized in that - that the connection is made by the anchoring points ( 1 ) located at the transition between the liquid distribution layer ( 2 ) and the liquid storage layer ( 3 ), - that the anchoring points ( 1 ) are formed on the one hand from multifilament fibre strands ( 5 ) protruding from the liquid storage layer ( 3 ) and on the other hand from staple fibres ( 6 ) protruding from the liquid distribution layer ( 2 ) and - that the fibre strands ( 5 ) and the staple fibres ( 6 ) are positively and force-fittingly connected to one another. 2. Composite material ( 4 ) for the management of body fluids according to claim 1, characterized in that the fiber strands ( 5 ) connected to the staple fibers ( 6 ) form fluid-conducting strands ( 7 ) between the fluid distribution layer ( 2 ) and the fluid storage layer ( 3 ). 3. Composite material ( 4 ) for the management of body fluids according to claim 1, characterized in that the surface area of all anchoring points ( 1 ) between the fluid storage layer ( 3 ) and the fluid distribution layer ( 2 ) is at most 10 percent of the total surface area. 4. Composite material ( 4 ) for the management of body fluids according to claim 1, characterized in that the liquid storage layer ( 3 ) and the liquid distribution layer ( 2 ) consist of thermoplastic polymers. 5. Composite material ( 4 ) for the management of body fluids according to claim 4, characterized in that said thermoplastic polymers are selected from the group of polyolefins. 6. Composite material ( 4 ) for the management of body fluids according to claim 4, characterized in that said thermoplastic polymers are selected from the group of polyethylene terephthalates. 7. Composite material ( 4 ) for the management of body fluids according to claim 4, characterized in that said thermoplastic polymers are selected from the group of polyamides. 8. Composite material ( 4 ) for the management of body fluids according to claim 1, characterized in that the staple fibers ( 6 ) contained in the fluid distribution layer ( 2 ) have a fineness of at least 3 to at most 16 dtex. 9. Composite material ( 4 ) for the management of body fluids according to claim 1, characterized in that the fibers ( 8 ) and filament strands ( 5 ) forming the fluid storage layer ( 3 ) have a fineness range of at least 0.3 to at most 20.0 dtex. 10. Composite material ( 4 ) for the management of body fluids according to claim 1, characterized in that the composite material ( 4 ) has a thickness of at least 0.1 to at most 4.5 mm. 11. Composite material ( 4 ) for the management of body fluids according to claim 1, characterized in that the composite material ( 4 ) has a basis weight of at least 20 to at most 500 g/m ² . 12. Composite material ( 4 ) for the management of body fluids according to claim 1, characterized in that the liquid storage layer ( 3 ) and/or the liquid distribution layer ( 2 ) are/is colored. 13. Composite material ( 4 ) for the management of body fluids according to claim 1, characterized in that the fiber strands ( 5 ) of the liquid storage layer ( 3 ) and/or the staple fibers ( 6 ) of the liquid distribution layer ( 2 ) are provided with a hydrophilic finish on their surfaces. 14. Composite material ( 4 ) for the management of body fluids according to claim 1, characterized in that the fiber strands ( 5 ) of the liquid storage layer ( 3 ) and/or the staple fibers ( 6 ) of the liquid distribution layer ( 2 ) are provided with an antibacterially effective finish on their surfaces. 15. Composite material ( 4 ) for the management of body fluids according to claim 1, characterized in that the liquid distribution layer ( 2 ) containing staple fibers ( 6 ) is a hydrodynamically consolidated nonwoven fabric. 16. Composite material ( 4 ) for the management of body fluids according to claim 1, characterized in that the liquid distribution layer ( 2 ) containing staple fibers ( 6 ) is a thermally bonded nonwoven fabric.