WO1990004376A2

WO1990004376A2 - Multilayer absorbent pad

Info

Publication number: WO1990004376A2
Application number: PCT/CH1989/000183
Authority: WO
Inventors: Demetrio Leone
Priority date: 1988-10-24
Filing date: 1989-10-17
Publication date: 1990-05-03

Abstract

A multilayer absorbent pad consists of cellulose-containing fibres, thermoplastic fibres and variable chemical absorbents. In the process for making the absorbent pad, a continuous or discontinuous homogenous fibrous layer is formed and at least one chemical absorbent is added in a differential manner to the various sections. The essentially strip-like absorbent layers (1 - 5 or 1 - 3), which are disposed longitudinally or transversely, are superimposed in a predetermined arrangement and bonded mechanically and/or thermally to each other and/or to other layers. The first or upper absorbent layer (1) of the absorbent pad has an absorptive power less than 30 ml/g and at least one of the underlying absorbent layers (2 - 5) has an absorptive power equal to or greater than 30 ml/g.

Description

Multilayer absorbent pads

The present invention relates to a process for the production of multi-layer absorbent pads made of cell pulp fibers, thermoplastic fibers and variable chemical absorbers, as well as by the method of manufacture.

Suction pads are used as diapers for babies and adults, for incontinence pads, for monthly and weekly padding, for tampons, for medical and other applications. To increase their absorbency and thus reduce their thickness, the absorbent pads are provided with a absorbent active chemical absorbent, in particular a so-called "superabsorber". This absorbent is added to a fluff of cellulose and thermoplastic fibers, this fluff is laid between wipes or nonwovens and thermally bonded by means of hot blasting, contacting with a hot surface or with infrared radiation, which is also called thermobonding. Although absorbent pads with superabsorbers have a significantly higher absorbent capacity-and thus are considerably thinner than the usual cellulose absorbent pads-the problems of back-wetness remain due to a smooth liquid distribution within the diaper, i. that due to the body pressure, the diaper remains too dry on its surface.

From EP-A2 0210968 is a chemical absorbent for absorbent pads of diapers and the like. known, which is specifically distributed in einla¬ Gigen absorbent pad. In general, the concentration of the absorbent increases in the direction of the side facing away from the human body to the Saugkissehs. In the middle wetting zone, a range of higher concentration of absorbents extends to the surface of the human body facing surface Absorbent pad. These density gradients produce a corresponding absorption gradient in all directions, but without layer structure.

US-A 4338371 discloses a multilayer absorbent pad for diapers and the like. Under a cover layer, which is intended for skin contact, is a first Faser¬ layer which extracts the liquid from the cover layer. Adjacent to this first fibrous layer are two absorptive layers with a high liquid absorption capacity arranged in doors or webs. The conclusion forms a flüssigke tsundurchlässige, but gasdurchläs¬ s ge outside.

US Pat. No. 4,590,114 describes a stabilized network of cellulosic fibers (thermo-mechanical pulp) and thermoplastic fibers which form suitable interspaces after the thermal bond to absorb moisture. The stabilization prevents one; Agglomeration and collapse of the network structure when moisture absorption. Furthermore, a two-layer composite layer is shown, which has a paper-like connected, thin cover layer. The layers are used for the production of diapers and the like.

The abovementioned and other known processes for the production of multi-layered absorbent pads of interest here have not proved successful in the mass production of diapers and inserts for infants and adults suffering from incontinence and / or cause mechanical engineering problems in all variants.

It is an object of the present invention to provide a process, particularly suitable for mass production, for producing multilayer absorbent pads of the type mentioned at the outset and absorbent layers produced therewith, which do not have the disadvantages of the known and which, moreover, produce a much more rational production qualitative tively better diapers and the like. Allow.

With regard to the method, this object is achieved by forming a coherent or discontinuous, homogeneous fibrous layer to form the absorbent pads and by at least one chemical absorbent being added differently in sections, the substantially strip-shaped, separate absorbent layers in a preselected one Arrangement are placed on each other, and this arrangement of the absorbent layers with itself and / or with other layers mechanically and / or thermally connected.

With the method according to the invention, multi-layered absorbent pads can be produced in a simpler and more economic way, thanks to the added thermoplastic fibers, but nevertheless elastic absorbent layers, in a simpler and more economical manner. With this a more rational manufacturing zul¬ the method produced absorbent pads have the be¬ known advantage that the close-to-body moisture is drawn into the absorbent pad due to the different absorption properties of the absorbent layers used and so¬ ever with an almost dry surface of Saugkis , - sens causes, ie The diaper always gives a feeling of dryness when worn. This allows a diaper to be worn for about ten hours without any annoying return wetness.

The chemical absorbent is advantageously added in sections during the formation of the fibrous layer in fine grains or as a powder. Depending on the dosage, this allows a complete saturation of the fiber layer with chemical absorbents or a greatly reduced, eg approximately half, coverage of the layer. The metering of the respective absorbent layer takes place according to the required absorption properties. Furthermore, an anti-septic agent and / or a deodorant can be added simultaneously. The separation by means of a water jet or a cutting blade is particularly advantageous in a longitudinal separation of the suction layers. This allows a particularly fast and easy-to-use production of diapers.

On a support layer, arranged from a continuous cloth or nonwoven absorbent layers, which are arranged at a distance zueinan¬, have proven particularly at a lower proportion of thermoplastic fibers, since in this case the produced absorbent layers are least stable and thus less can be transported well in the machine.

Individually applied on a support layer suction pads kön¬ NEN be brought by folding the support layer in the preselected position. This has the advantage that the Saugschich¬ th no longer need to be separated and thus can be folded up immediately after the Thermobondi ng. It is characterized at the same time the arrangement of the 'absorbent layers at least partially connected in itself.

Suction pads having a plurality of layers of a textile-containing material produced by the method are characterized in that the first absorbent layer has an absorption capacity of less than 30 ml / g, and at least one of the underlying absorbent layers has an absorption capacity of 30 ml / g or more.

It has proven particularly useful to use powdered or faserfδrπtiges absorbent because coarser grains are soon noticeable in the small thickness of the absorbent pad. The absorption capacity of a suction layer is determined primarily by the content and the type of chemical absorption medium n.

For diapers and insoles for infants, preference is given to The absorbent pad has at least two layers, wherein the first absorbent layer contains at most 2% by weight, here and in other respects based on the fiber material, of a chemical absorbent having a retention of less than 10 ml / g, and at least one of underlying absorbent layers containing at least 2 wt .-% of a chemical Absorp¬ tion medium, with a retention more than 20 ml / g, in particular between 35 and 65 ml / g.

Diapers and insoles for adult incontinent sufferers preferably have absorbent pads having at least four layers, the lower absorbent layers suitably containing alternately 2 to 10% and 10 to 20% by weight of chemical absorbent.

The invention will be explained in more detail with reference to the dargestell¬ th in the drawing embodiments, which are also the subject of abhän¬ gigen claims. The vertical sections show schematically:

1 different absorbent layers immediately after production, FIG. 2 separate absorbent layers, FIG. 3 an arrangement of superimposed absorbent layers according to FIG. 1, FIG.

Fig. 4 shows an arrangement of absorbent layers accordingly

Fig. 3, with a folded support layer, and Fig. 5 shows an arrangement according to Fig. 4 with another Fal¬ device.

FIG. 1 shows a section with the sequence of different absorbent layers 1 to 5, immediately after their production. The first absorbent layer contains about 1% by weight of a chemical absorbent which is added during formation of the absorbent layer of pulp and thermoplastic fibers. The pulp and thermoplastic fibers are preferably in a ratio of 30: 1 and 4: 1, in particular about 7: 1, intimately mixed and thermally bonded ^" .

Chemical absorbents, in particular a superabsorbent, are highly absorbent polymers which can bind a multiple of their face to saline-containing water or urine and thereby form a gel which remains stable even under pressure influence. This retention is a particularly important property for diapers, pads, sanitary napkins, tampons and the like. The wicking speed of a superabsorbent is mainly dependent on grain size, i. For smaller grains, the entire surface of the superabsorbent is larger and therefore absorption or gel bonding is much faster. The adjustment of the absorbency of a suction layer is achieved with superabsorbents of different types and / or quantities.

The following products have distinguished themselves as superabsorbents:

Aridall 1125 of _. Chemdal, USA

Drytech 510 from Dow Chemical, USA ^"

PR 9910 S from Floerger, U.S.A.

FAVOR 922 SK from Stockhausen, D-Krefeld Fibersorb SA 7000 from Arco Chemical, U.S.A.

The second absorbent layer 2 is partially, i. about 2 wt .-%, provided a slow superabsorber. The particle size distribution is such that at most 2% are greater than 800 μm and at most 3% smaller than 100 μ.

The third absorbent layer 3 is enriched with about 15% by weight of a slow superabsorber.

The fourth absorbent layer 4 is provided with about 5 wt .-% of a fast superabsorber. The grain size distribution of the fast superabsorber is such that high at least 2% larger than 400 μm and at most 4% smaller than 100 μm.

The fifth absorbent layer 5 is provided with about 15% by weight of a fast superabsorber.

It is also possible to use one and the same powdery or fibrous superabsorber for all five absorbent layers 1 to 5. The concentrations of the superabsorber are then 1% by weight for the first absorbent layer, 2% by weight for the second absorbent layer, 5% by weight for the third absorbent layer, 10% by weight for the fourth absorbent layer and for the fifth absorbent layer 15 wt .-%, always based on the fiber material.

In both variants, the uppermost or first absorbent layer 1 has an absorbency of less than 30 ml / g and a retention of less than 10 ml / g. The underlying suction layers 2 to 5 all have an absorption capacity of more than 30 ml / g and a retention of more than 20 ml / g, in particular after the first variant, the retention in the absorbent layers 3 and 5 are between 35 and 65 ml / g.

FIG. 1 indicates that further sequences of absorbent layers follow continuously on both sides of the row of absorbent layers 1 to 5.

The absorbent layers according to FIG. 1 can be arranged longitudinally or vertically with respect to the production direction, depending on the available forming station.

In FIG. 2, in the longitudinal direction, the same series of absorbent layers 1 to 5 are arranged in continuous succession on a carrier layer 6, a cloth or web of cellulose, only the absorbent layers 1 to 3 being visible.

The continuous sequence of FIG. 1 produced Absorbent layers 1 to 5 are separated from one another with suitable separating means, for example with a cutting blade or by means of a jet of water, and laid one on top of another according to the arrangement in FIG. In this case, a suction pad is formed with the first absorbent layer 1 close to the body when worn, the three intermediate absorbent layers 2, 3 and 4 underneath and the absorbent layer 5 at the bottom. The separation can also be done after the layers are stacked.

In the order given, it is achieved that the moisture absorbed by the absorbent layer 1 is absorbed mainly by the absorbent layers 3 and 5 and therefore the other absorbent layers 2 and 4 only need to absorb the residual moisture. The first absorbent layer 1 further has the essential function of preventing rewet of the underlying absorbent layers 2 to 5 when the absorbent pad is pressed, so that an approximately dry, near-bodily surface of the absorbent pad is always retained, ie. the absorbent layer 1 verli ht. always a dry feeling.

For the production of baby diapers or insoles, only the top three absorbent layers 1 to 3 can be used. Diapers or incontinence pads for adults are preferably made from a suction pad with the five suction layers 1 to 5.

If the absorbent layers 1 to 5 are produced at a distance on a moisture-permeable support layer 6, they can be laid on one another by folding the backing layer 6 according to FIG. 4. The individual absorbent layers 1 to 5 then no longer need to be separated from each other. In this arrangement, the first absorbent layer 1 is connected at the top to the base layer 6, the second absorbent layer 2 is attached to the bottom, etc.

FIG. 5 shows another arrangement of the folded carrier layer 6. In this folding arrangement is the Support layer 6 each two times between the adjacent absorbent layers. Although this arrangement appears to be much thicker compared with FIG. 4, the thickness of the base layer 6 is of secondary importance in practice, so that only the interval production of the absorbent layers and the simplest folding method are decisive for the production speed.

The absorbent layers 1 to 5 can, instead of as shown in relation to the longitudinal variant in Fig. 1, also in tracks side by side - are produced in the properties and / or in the amount of different absorbents. These webs are then placed one on top of the other as shown in FIG. 3 and subsequently separated to the desired diaper or egg ng sizes. The _U. The same is done by means of the "looping" method known per se, ie the respective track is directed obliquely around a roller, whereby it undergoes a parallel displacement. By suitable paral lel displacement of all tracks they come to lie one above the other.

Another possibility of the parallelization is that the tracks are guided on curved surfaces which have the profile of an S-curve. The S-curves are designed in such a way that the tracks are finally all one above the other.

Claims

- 1 3 -patent claims

1. A process for the production of multilayer absorbent casings from cellulose fibers, thermoplastic fibers and variable chemical absorbents,

characterized in that

to form the absorbent pads a coherent or discontinuous, homogeneous fiber layer is formed and wenig¬ least one chemical absorbent is added differently in sections, the gene substantially strei fenförm, separate absorbent layers (1-5 or 1-3) are placed on each other in a preselected arrangement , And this arrangement of the absorbent layers is mechanically and / or thermally connected to itself and / or with other layers.

2. The method according to claim 1, characterized in that the / the chemical / n absorbents depending on the preselected absorbency of the respective Saug¬ layer (1-5) is added within the arrangement in a preselected type and concentration / are.

3. The method according to claim 1 or 2, characterized gekennzeich¬ net, that a continuous layer is separated into individual, strip-like absorbent layers (1-5), preferably by means of at least a water jet or cutting blade, wherein the strip-shaped absorbent layers according to the applied absorbent in be¬ zug on the manufacturing direction longitudinally or verti¬ kal be separated.

4. The method according to claim 1 or 2, characterized gekennzeich¬ net, that the absorbent layers (1-5) on a support Layer (6), preferably made of a continuous cloth or non-woven, are formed at intervals to each other.

5. The method according to claim 4, characterized in that the individual absorbent layers (1-5) are brought by folding the support layer (6) in the preselected arrangement.

6. With the method according to one of claims 1 - 5 presented herge¬ Saugkissen with several absorbent layers of zel 1 - material material, characterized in that the first absorbent layer (1) has an absorption capacity of less than niger than 30 ml / g, at least one the underlying absorbent layers (2-5) has an absorbency of 30 ml / g or more.

7. absorbent pad according to claim 6 with at least two Schich¬, characterized in that the first absorbent layer (1) contains at most 2 wt .-% of a chemical Absorptionsmit¬ means, with a retention of less than 10 ml / g, and at least one the underlying Saug¬ layers (2-5) contains at least ^" 2 wt .-% of a chemical absorbent, with a retention of more than 20 ml / g, in particular between 35 and 65 ml / g.

8. absorbent pad according to claim 7 with at least four Schich¬, characterized in that the lower Saug¬ layers (2-5) alternately contain 2 to 10 wt .-% and 10 to 20 wt .-% of chemical absorbent.