DE4114839C2 - Composite nonwoven material - Google Patents

Description

The invention relates to a composite nonwoven material according to the Preamble of claim 1.

Microfiber fleeces are known to be made after the melt blown Process manufactured. they consist of discontinuous fine microfibers with relative small diameters of approximately less than or equal to 10 µm. In the melt-blown process, the microfibers formed from a thin melt under the influence of a strong air stream Nozzle is pulled off. After cooling, form then the fine microfibers on a mesh belt too  the microfiber fleece are deposited.

The application possibilities of microfiber nonwovens are in practice very diverse. So it is through the German Patent specification DE 23 56 720 C2 known, on a pile layer, that is, on a layer of each other unsolidified fibers of essentially endless coarse filaments with relatively large diameters Apply microfiber fleece as a further layer and the The pile layer and the microfiber fleece so together connect that the microfiber fleece while melting at least partially penetrates the pile layer. At Melting flows around the fibers of the microfiber fleece the fibers of the pile layer, the microfibers their lose original fiber structure. After cooling the fibers of the pile layer are connected to each other, so that the pile turns into a stable fleece. The microfiber fleece is thus used to form the fleece Fibers from the original pile layer are used.

DE 39 20 066 A1 is also a  Composite nonwoven material known, which also consists of two Components consists, namely of the essentially endless coarse filaments with relatively large Diameters as well as from the discontinuous fine Microfibers with relatively small diameters. The microfiber fleece is not as a discrete layer from the fleece layer with the coarse Filaments separated, but penetrates the fleece layer at least partially. The composite nonwoven material is a mixture of the two components (rough Filaments and fine microfibers), without discrete layered phase boundaries between the individual components.

This also applies to this known composite nonwoven material Microfiber fleece helps to improve the properties of the To improve composite nonwoven material overall to achieve the desired qualities.

In practice, this now results in further use the well-known composite nonwoven materials - but also generally when using nonwovens - the Need to glue the fleeces to theirs  final purpose of use. Especially clear this problem occurs in the manufacture of diapers or other hygiene items. Here, the Nonwovens used to transport fluid to the Allow absorbent body of the diaper, whereby at the same time a return transport in the absorbent body stored liquid to the outside can be avoided should.

So far, one has in the manufacture of diapers Absorbent body with both the back film and with glued to the upper fleece or the composite fleece material. To do this, the diaper producer who is done with it Covered fleece is present, an adhesive in liquid form applied the fleece. As long as the glue is still hot the fleece is on the absorbent and in the Edge areas outside the absorbent on the pressed back film.

During this gluing process, make sure that the Under no circumstances should glue be applied over the entire surface may, but only in discrete individual places. In any case, such areas must exist that are not provided with the adhesive. The one with the Areas with adhesive prevent them  required function of the fleece, one Moisture transport through the fleece to the To ensure absorbent body.

The adhesive is therefore usually linear applied by about 0.5 mm wide every 3 cm Adhesive line is generated, so as many Be rich without producing glue. It is also known that Spin hot or spray on glue or the Apply glue from a slot nozzle to the fleece, whereby discrete islands of adhesive form on the fleece.

In any case, there are always certain areas namely the adhesive areas, one where the function of the fleece prevented and moisture transport through the fleece is not possible.

In addition, there is also when ordering the hot Glue itself problems. Since the glue is liquid, it can it may penetrate through the fleece. At the Subsequent folding and packaging of the diaper does this to the fact that the manufactured diapers, for example no longer let it unfold.

When the glue completely penetrates the fleece and it  thus an adhesive breakthrough results as Another disadvantage of the effect that at these points unwanted hardening occurs.

There are further problems with the order of a constant amount of glue. When using It always happens with conventional slot nozzles or spray nozzles again that these clog selectively, what in disadvantageously to an uneven application of adhesive leads.

Finally, it should also be mentioned that the application of the glue itself as a necessary operation time-consuming and therefore economically is inexpensive.

To avoid all of the disadvantages described Invention based on the task of a simple and easy bonding of nonwovens without negative side effects.

This task is performed on a composite nonwoven material the preamble of claim 1 by the in the mark this claim specified features solved.  

The invention breaks new ground, microfibers a microfiber fleece by one or more Form components of an adhesive. This adhesive or the components are designed so that they Working temperature of the manufacturing process of the Microfiber fleece one for the formation of the Microfiber fleece suitable thin liquid state have. The new microfiber fleece can be used with it conventional process technologies, especially after Manufacture melt blown process.

Another feature of the adhesive or the components is that the microfibers at normal Ambient temperature lose their adhesiveness and thus like conventional microfibers of a microfiber fleece can be used. Because of warming they are However, microfibers can be reactivated and can then be used as Glue work. After completing the heating or Gluing process when the microfibers are back take normal ambient temperature, they do not work more than glue, but like conventional microfibers  inside a microfiber fleece.

The microfiber fleece created by the invention differs at normal ambient temperature in principle not from a conventional microfiber fleece. Of What is important, however, is that the microfibers are heated can be reactivated as an adhesive. An iron on Comparable, it is therefore possible to use the microfiber fleece to give an adhesive function at the elevated temperature and thus glue nonwovens. Just be discreet When heated, the gluing only takes place these discrete places.

For heating can also be known per se Ultrasonic welding processes are used.

The is particularly advantageous in practice Use of the microfiber fleece according to the invention to look at the composite nonwoven materials mentioned at the beginning, where the microfibers become sticky when heated develop. It is important that the microfibers of the microfiber fleece according to the invention in the cold state, the properties and at ambient temperature Have functions known microfibers. This ensures that the microfibers in the  Composite nonwoven materials especially the functions can take on them at these Composite nonwoven materials are attributed.

The new microfiber fleece therefore has a multi functional effect. It enables the bonding of one Composite nonwoven material, for example in the manufacture of diapers, and it is also part of the Fleece quality itself. The fiber structure of the microfibers of the new microfiber fleece stays next to the Preserved property as a reactivatable adhesive.

Thus, in the known composite nonwoven material according to the patent DE 23 56 720 C2 that on the Fleece layer from the coarse filaments applied Microfiber fleece in an advantageous manner according to the Design invention. The new microfiber fleece is So applied to the nonwoven layer and if necessary bonded to the nonwoven layer by melt embossing. The The two layers can be connected support advantageously by the microfiber fleece is heated and reactivated as an adhesive. In addition to the melt embossing can also be used supporting adhesive connection can be made. To the microfiber fleece behaves when it cools down  then like a normal fleece, because its Fiber structure has not been destroyed.

The invention can also be applied to microfibers  use textile fabrics, and also at Composite nonwoven materials with staple fibers. In any case the advantage can be realized, the microfiber fleece reactivate by heating as an adhesive.

The composite nonwoven materials can also be sandwiched, in such a way that the middle layer through the essentially endless coarse filaments is formed, and that the two Outer layers in the form of the new microfiber fleece are trained.

The advantage of the invention becomes particularly clear when you look at the production of Leads to diapers. It is enough that Composite nonwoven material on the absorbent and in the Place marginal areas on the rear film and the Then glue by heating bring about. After cooling, the composite fleece is material safely with the absorbent and the film connected. The complex described above The process of applying an additional adhesive can completely eliminated.

Even with the use of the known glue  resulting disadvantages occur when using the invention no longer on. After the microfibers cooled down again, they look like normal Microfibers in a microfiber fleece because they are yours Have retained the fiber structure. There is none Adhesive punctures more, and especially kick no more areas where the function of the Composite nonwoven material is disturbed, a liquid to allow transport to the absorbent.

It is understood that the temperature at which the Reactivation of the microfibers takes place as an adhesive, see above is chosen small that the fleece layer from the coarse Filament itself is not damaged, and that also the Body to which the composite nonwoven material is applied should not be affected either becomes.

Based on the execution shown in the drawing games, the invention is explained in more detail. Show it:  

Fig. 1 is a cross-sectional view of a micro-fiber fleece in schematic Dar position,

Fig. 2 is a schematic representation of a composite nonwoven material using a microfiber web, and

Fig. 3 is a schematic cross-sectional view of a diaper.

In Fig. 1 in a schematic cross-sectional view of a microfiber web 10 is shown, which blown method is made of melt-fine microfibers 12 after. The microfibers 12 are formed by components of an adhesive and can consist of ethylene butyl acrylate and / or ethylene methyl acrylate. These are adhesive components which have the suitable low-viscosity state at the working temperature for producing the microfiber fleece 10 . Furthermore, the adhesive components mentioned are such that they have the usual functions of microfibers in relative cold or at normal ambient temperature, but that when heated to z. B. 100 ° C can be reactivated and act as an adhesive.

With the help of the microfiber fleece 10 , it is therefore possible to reactivate the adhesive function by heating and thus to connect objects, in particular nonwovens, to one another.

Fig. 2 shows a composite nonwoven material 16 of the fine microfibers 12 and the coarse filaments 18th The composite nonwoven material 16 consists of an upper nonwoven layer 20 and a lower nonwoven layer 22 . The fleece layer 20 is formed by the fine microfibers 12 and thus represents a microfiber fleece 10. In contrast, the fleece layer 22 consists of the coarse filaments 18 .

The composite nonwoven material 16 according to FIG. 2 is therefore characterized by a layered structure of the two nonwoven layers 20 and 22 . In the composite nonwoven material 16 , the fine microfibers 12 are designed as adhesives in the manner already described above.

An advantageous application of the invention is explained below with reference to FIG. 3, which shows a diaper 30 in a schematic cross-sectional view. The diaper 30 consists of a absorbent body 24 , the rear film 26 and an upper composite nonwoven material.

In the manufacture of the diaper 30 , the composite nonwoven material 16 is placed on the absorbent body 24 and in the edge areas on the film 26 . The arrangement prepared so far is then guided past a heater in order to heat the fine microfibers 12 and to reactivate them as an adhesive. The microfibers 12 now act as an adhesive so that the composite nonwoven material 16 can be glued to the absorbent body 24 and the film 26 . Applying pressure makes the gluing considerably easier. Heated rollers through which the diapers 30 are guided are therefore particularly suitable for achieving the bond.

After subsequent cooling to ambient temperature, the microfibers 12 lose their adhesion again and they now only act as the usual microfibers of a composite nonwoven material.

After the microfibers 12 have cooled, there are no more adhesive spots, as is the case with the known adhesive process. The entire area of the composite nonwoven material 16 is thus available in order to transport the liquid to the absorbent body 24 .

Claims (7)

1. composite nonwoven material ( 16 ), which consists of a first consolidated nonwoven layer ( 22 ) and a second nonwoven layer ( 20 ) made of discontinuous, fine microfibers ( 12 ) with a relatively small diameter, the microfibers ( 12 ) of the second nonwoven layer ( 20 ) by means of a melt-blown process and applied to the first non-woven layer ( 22 ), characterized in that the material of the microfibers ( 12 ) consists of one or more components of an adhesive or of polymers which, when heated to a temperature which is essential is lower than the melting or decomposition temperature of the first nonwoven layer ( 22 ), develops a stickiness without losing its fiber structure, and that the material of the components is such that it is suitable for the working temperature of the melt-blown process the formation of the microfibers ( 12 ) has a suitable low-viscosity state and that the components are also obtained in this way n are that the microfibers ( 12 ) can be reactivated as an adhesive by heating to a temperature between 80 ° C and 180 ° C, so that the two non-woven layers ( 20 , 22 ) remain separated from one another by a discrete phase boundary ( 28 ) and lie in layers against one another and the first nonwoven layer ( 22 ) can be bonded to a further substrate via the microfiber layer ( 20 ) while maintaining its properties. 2. composite nonwoven material ( 16 ) according to claim 1, characterized in that the microfibers ( 12 ) can be activated by heating to a temperature of about 100 ° C as an adhesive. 3. composite nonwoven material ( 16 ) according to claim 1 or 2, characterized in that the component or components of the microfibers ( 12 ) assume the low-viscosity state at about 250 ° C. 4. composite nonwoven material ( 16 ) according to any one of the preceding claims 1-3, characterized in that the microfibers ( 12 ) consist of ethylene butyl acrylate. 5. composite nonwoven material ( 16 ) according to any one of the preceding claims 1-3, characterized in that the microfibers ( 12 ) consist of ethylene butyl acrylate. 6. composite nonwoven material ( 16 ) according to any one of the preceding claims 1-3, characterized in that the microfibers ( 12 ) consist of a mixture of ethylene butyl acrylate and ethylene methyl acrylate. 7. composite nonwoven material according to any one of the preceding claims 1-6, characterized in that the microfibers ( 12 ) have a diameter of less than or equal to 10 microns.