EP0211131A2 - Non-woven absorbent textile article for medical and hygiene uses, and method of making it - Google Patents

Abstract

A non-woven, textile absorbent body for use in the medical and hygienic field consists of at least one outer, thermally consolidated, hydrophobic fiber layer with at least 80% synthetic composite filaments and at least one layer of absorbent fibers. It is perforated without any significant intertwining of fibers and contains no binding agents. Furthermore, a method for producing the absorbent body is shown, wherein the fibers are placed on top of one another, perforated hydraulically without fiber entanglement, and then thermally consolidated via the composite filaments.

Description

The invention relates to a nonwoven, textile absorbent body for use in the medical and / or hygienic field according to the preamble of claim 1. Furthermore, a method for producing such an absorbent body is shown.

In medicine and hygiene, absorbent textile fabrics are required as surgical wound dressings, covering or swab material. Woven cotton gauze has the disadvantage of sticking to the wound when treating wounds. Furthermore, its ability to absorb wound secretion is unsatisfactorily poor.

To reduce the adhesive properties, unfolded compresses or the absorbent layer of wound dressings are covered with hydrophobic synthetic fiber layers made of fabric.

For example, EP-OS 77 034 describes an absorbent wound dressing made of a core of highly absorbent material with an at least two-layer covering on the wound side, the core-side layer of which consists of heat-sealable nonwoven fabric and the outer layer of which is made of polypropylene fabric with a lattice structure. This fabric, which is not a nonwoven fabric, is intended to facilitate the removal of wound exudate into the absorbent layers due to its sufficiently large openings, irregularly edged in comparison to perforated polypropylene foils, without clogging of the pores. The heat-sealable non-woven fabric connecting the outer lattice layer to the absorbent layer is thus brought very close to the wound. The edges of the two-layer cover can be welded into a suction pad.

However, this outer two-layer composite suffers from the foldability of the flat structures, which is often necessary in the interest of an increased suction effect: they often tend to break at the folds of the fabric covers under heavy use.

As a way out, very voluminous, non-foldable absorbent bodies must be made available in this embodiment, their handling is thus restricted and their packaging costs are increased considerably.

Furthermore, the fact that the polypropylene fabric layer must be prefabricated before the wound dressing is made contributes significantly to the increase in costs.

Covers with non-weldable cover fleeces are forbidden because of the polymer binder dispersions then required and their content of washable additives that are not physiologically acceptable in medicine.

The French patent application FR-A 2 536 432 shows a hydraulic perforation device and a method with which perforated, binder-free nonwovens can be produced predominantly from cellulose fibers with abrasion-resistant surfaces, the fibers being intertwined by needling with water jets of very high pressure. Compared to cotton gauze, these products are characterized by their approximately 50% higher absorption capacity for aqueous liquids.

However, the energy required for high-energy water jet needling is very high. Furthermore, this product also tends to stick to the wound because of the not inconsiderable content of cellulose on the surface. The object of the present invention is to provide a non-woven textile absorbent body which is particularly versatile in medicine, but also in the hygiene field, the absorbency of which corresponds to that of the perforated cellulose / cotton nonwovens, but which does not contain any binding agents and is nevertheless lint-free and friction-resistant also not glued to the wound and which allows multiple folds as required without damage. The advantages of known medical absorbent bodies that have not previously been achievable together should therefore be combined in one product.

Furthermore, the task is to demonstrate a cost-effective and simple method for producing such an absorbent body, with which the technical outlay of water jet needling and the use of a two-layered one. Nonwoven / fabric cover can be bypassed and yet no binding agent is required for consolidation.

The object is achieved by the features of the absorbent body specified in the characterizing part of patent claim 1; the method for its production is evident from claim 6. The fiber layers of the absorbent layer and the hydrophobic cover flow smoothly into one another: due to the thin layer layer on top of each other, in combination with the subsequent thermal bonding under pressure, they no longer have any defined boundary layers, so that the product according to the invention as a fiber layer composite, however, no longer must be referred to as laminate.

The hydrophobic outer layer according to the invention contains each min- _de least 80tl synthetic composite filaments having a high- and a low-melting component. The remaining fibers can be synthetic homofil fibers, possibly with a small proportion of cellulosic fibers.

The absorbent fiber layer generally consists of the known cellulosic fiber materials, optionally in a mixture with other fibers. It is advisable to add strengthening binding fibers. In the interest of cost-effective production and to maintain the bulkiness of the suction zone, a content of up to 30% of composite filaments of the same type as in the hydrophobic cover is advantageous. These binding fibers also serve to connect the suction zone to the outer layer (s).

According to a further, particularly preferred variant of the absorbent body according to the invention, the absorbent zone contains together with cellulosic fibers or consists entirely of polyvinyl alcohol fibers softenable in hot water. This configuration has the advantages that binding fibers can be dispensed with, since they are self-adhesive under the conditions mentioned, and that they also have a significantly higher absorption capacity for aqueous liquids than cellulosic fibers.

In a further advantageous embodiment of the absorbent body according to the present invention, the suction zone consists only of cellulose paper, expediently in several layers. This version is preferred for hygienic applications. Pulp is inexpensive and has such a strong internal cohesion that it can also be dispensed with with binder fiber additives, even when subjected to heavy use when dry.

The absorbent body according to the invention has continuous perforations distributed over its entire surface. However, according to the invention, even in the perforated areas, it does not contain any essential fiber entanglements that contribute to strengthening. The composite is thermally bonded exclusively via the low-melting component of the composite fibers; its hydrophobic outside or outside has a lint-free structure.

The weight of the finished material is expediently in a range between 30 and 50 g / m ² , the weight fraction of the hydrophobic outer layer or layers being intended to be as low as possible in the interest of foldability and absorbency, for example 6 g / m ² in each case with a fiber titer of 1.7 dtex.

The non-absorbent surface of the absorbent body can be rough or smooth; the former property is more suitable for wound cleaning products, the latter is more suitable for wound dressings (as little bondability to the wound as possible).

In a special embodiment of the absorbent body according to the invention, at least one fiber layer contains shrunk polyester fibers. These bring about a mechanical consolidation of the non-perforated zones both in and perpendicular to the fiber planes, the extent and the direction of this consolidation being easily varied by the number of shrink fibers and by the fiber orientation. Such absorbent bodies are distinguished by an increased fluid absorption capacity because of their increased bulk, in particular after repeated folding.

The product according to the invention can be used in a variety of ways both in the medical and in the hygienic field. It has an absorbency that is at least equal to that of the well-known perforated layered nonwovens, but does not contain any binder additives and is nevertheless lint-free and very tear-resistant.

The openings of the cover formed by the welded component fibers are irregular and large enough to ensure reliable secretion transport to the suction layer. It is therefore achieved with this completely non-woven absorbent body as with the known two-layer fleece / fabric covers without having to provide such a fabric.

Sticking to the wound is effectively prevented by the hydrophobic fiber layer, possibly in a smoothed form. In addition, the absorbent body can be folded multiple times without damage and in this state can easily be thermally sealed to a very voluminous absorbent body, and because of the content of thermoplastic fibers in the outer layers, it can be welded along its edges, in the case of a two-layer design after folding once, to a suction pad, on the sides of which an undesirable fiber leakage from the absorbent layer is thus reliably excluded.

The claimed process for the production of the absorbent body according to the invention consists first of all in depositing at least two fiber layers on top of one another, one of which contains the known absorbent fibers and the other contains hydrophobic, thermoplastic composite filaments. At least 80% of composite filaments are used for the outer hydrophobic layer or layers. The fiber scrim is then exposed to thin water streams of such low energy that there is no substantial fiber entanglement, but only hydraulic perforation.

Hydraulic perforation with low-energy water jets, however, requires additional consolidation, since this alone does not result in fiber entanglement and no abrasion-resistant surface. With the present invention, this method is used without the use of a binder, since multicomponent fibers alone bring about the strengthening.

To perforate the fiber composite, water is pumped through a slot nozzle that extends over the entire width of the material at a pressure that is just sufficient for perforation. A suitable device is e.g. described in detail in French patent application FR-A 5 536 432.

The "water curtain" that forms strikes a perforated, rotating template that moves with the fiber layers, the fibrous web underneath being perforated by the water that passes through without substantial fiber entanglement according to the perforated structure of the template. The open area of the perforated template is expediently chosen to be as large as possible because this makes the longitudinal and transverse webs of the perforated fleece highly voluminous and thus creates further liquid-absorbing capillary spaces in the finished absorbent body. Furthermore, these voluminous "webs" increase the abrasiveness of the surface, which is particularly advantageous for 4-year cleaning and cosmetic applications.

Following the perforation, the water is removed by drying, the sheet is thermally solidified at a temperature above the melting point of the low-melting component of the composite filaments and, if necessary, the hydrophobic surfaces are subsequently smoothed.

Both core-sheath and conjugated (side-by-side) fibers can be used as composite filaments.

In order to increase the strength and reduce the adhesiveness of the wound, the outer surfaces of the dried and solidified absorbent body consisting of composite filaments can be thermally smoothed using the known calendering process. If you want to leave the volume of the product relatively large, two smooth rollers, ie. H. with a relatively low pressure, smoothed. By changing the roller gap, the volume of the absorbent body can be varied as desired.

Higher drapability or foldability, on the other hand, is achieved with welding that does not cover the entire surface, in which case the engraving depth of the roller should expediently not be chosen too small because of the volume retention. In a special embodiment of the invention, one or more fiber layers are blended with polyester fibers that are highly shrinkable in hot water or steam. During the drying process, the perforated, still wet fabric shrinks. This involves mechanical strengthening by compressing the fiber bundles along the longitudinal and transverse webs and partly by reorienting the fibers into the vertical. The amount of shrinkage in the longitudinal and transverse directions depends primarily on the fiber orientation and the shrinkage fiber content. After drying is complete, the fiber is consolidated again by exceeding the melting temperature of the lower-melting component of the heterofil fibers. The aforementioned reorientation of the fibers is associated with an increase in volume which, after one or more folds, is particularly noticeable due to an increased fluid absorption capacity.

In order to achieve a high production speed and therefore good economy, fiber webs are usually laid lengthways. The associated very low transverse strengths can be increased as required in a simple manner by stacking each layer at right angles to the next lower one. Such an arrangement is particularly advantageous for absorbent bodies in the operating theater where high tear resistance is required.

In order to avoid yellowing or other thermal damage to the inner, absorbent fiber layer, the low-melting component should expediently be activated at a temperature which the absorbent fibers can survive without damage. Such composite filaments consist, for example, of polyethylene terephthalate / polyethylene (or polypropylene). The fiber with the polypropylene component is also resistant to steam sterilization; this configuration is therefore preferable for folding compresses to be sterilized in the autoclave. In order to ensure good foldability, the titer of all fibers should be as low as possible, i.e. they should have the lowest possible stiffness.

The method according to the invention permits the continuous, inexpensive and rapid production of highly effective textile absorbent bodies. It is essential that the hydraulic perforation is carried out in principle according to FR-A 2 536 432, but according to the invention with a low-energy "water curtain". This measure, together with a binder-free consolidation, satisfies all the requirements specified in the task for a textile composite that can be used for medicine and hygiene.

• Figur 1 in der Draufsicht einen Saugkörper gemäß der vorliegenden Erfindung in 20facher Vergrößerung;
• Figur 2 den Querschnitt durch einen dreilagigen Saugkörper in 100facher Vergrößerung.

The invention is further illustrated by the following examples and illustrations. Show it:

• Figure 1 in plan view of a suction body according to the present invention in 20 times magnification;
• Figure 2 shows the cross section through a three-layer absorbent in 100x magnification.

example 1

A three-layer stacked nonwoven fabric is made from several cards: the two outer layers each consist of 7 g / m ^{2 of} a polyester / polyethylene bicomponent fiber with a titer of 1.7 dtex and a cutting length of 40 mm, the absorbent middle layer of 26 g / m ^{2 of} a blend made of 80% viscose cellulose with a titer of 1.3 dtex and a cutting length of 40 mm and 20% of the above-mentioned composite filaments.

The staple fiber composite with a total weight of 40 g / m is wetted by spraying with water before the hydraulic perforation. The perforated template used contains rectangular perforations with dimensions of 1.4 mm across and 2.5 mm along the direction of travel. The web widths are 0.50 mm throughout. The open area therefore amounts to 55%, based on the entire stencil surface.

The thin water curtain (approx. 60 µm) from a slot nozzle applies approximately 10 bar to the template. After perforation, the air is dried at 160 ° C. and solidified. The result is a voluminous, highly absorbent and yet abrasion-resistant medical absorbent. Both in the folded and unfolded state it has a significantly higher water absorption than cotton gauze or commercially available, water-jet needled products.

FIG. 1 illustrates how, in the case of an absorbent body according to Example 1, the hydraulic perforation with water jets of low energy causes perforation without much higher fiber entanglement in the perforated area than is already the case in the non-perforated zones.

Figure 2, a cross section through the absorbent body according to Example 1, clearly shows that after the deposition, perforation and consolidation of the nonwoven composite, this no longer constitutes a pure laminate, since the upper or lower (hydrophobic) fiber layers partially penetrate or wrap around the absorbent middle layer .

Example 2

The absorbent body manufactured according to Example 1 is smoothed on one side at 105 ° C. against a smooth, PTFE-coated fabric. The result is an absolutely lint-free, smooth surface. The material is superior in terms of non-wound adhesive folded gauze and gauze substitute based on water jet needled nonwoven.

Claims (8)

1. Non-woven, textile absorbent body for use in the medical and hygienic field, consisting of at least one absorbent fiber layer, optionally mixed with binding fibers, and at least one hydrophobic outer fiber layer made of nonwoven fabric that covers this at least on the wound side, with continuous perforations distributed over the entire surface of the absorbent body are present, characterized in that the hydrophobic fiber layer each consists of at least 80% of synthetic composite filaments with a low and a high melting component, that the fiber layers flow into one another, that the perforated areas do not contain any significant fiber entanglements and that the entire composite is exclusively over the composite filament is thermally bonded without binder. 2. Absorbent body according to claim 1, characterized in that the absorbent layer contains up to 30% composite filaments of the type mentioned in claim 1. 3. Absorbent body according to claim 1, characterized in that the absorbent layer contains softenable polyvinyl alcohol fibers in hot water. 4. Absorbent body according to claim 1, characterized in that the absorbent zone consists exclusively of cellulose layers. 5. Absorbent body according to one of the preceding claims, characterized in that at least one fiber layer contains shrunk polyester fibers. 6. A process for the production of a non-woven, textile absorbent body for medicine and hygiene, wherein at least one absorbent fiber layer, optionally containing binding fibers, and at least one outer layer containing hydrophobic fibers covering it are placed on top of one another and then the composite is hydraulically continuous by means of a slit-shaped water nozzle and a perforated template is perforated, characterized in that at least 80% synthetic composite filaments with a low-melting and a high-melting component are used for the hydrophobic fiber layer, that one then perforates with water currents of such a low impact energy that no significant fiber entanglement occurs in the hole areas, and that one then Removed water by drying, the composite solidified under pressure at a temperature above the melting point of the low-melting component, without the addition of a binder, and optionally one or both surfaces thermis ch smoothes. 7. The method according to claim 6, characterized in that at least one fiber layer is provided with shrinkable polyester fibers in hot water or steam and their shrinkage takes place simultaneously with the drying. 8. The method according to claim 6 or 7, characterized in that only one or more layers of cellulose are used for the suction layer and these are moistened before the hydraulic perforation.

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