DE1947176A1 - Method and device for the production of perforated nonwovens - Google Patents

Description

Carl Freudenberg ON 525

69H0 Weinheim / Bergstr.

Method and device for the production of perforated nonwovens

So-called nonwovens or "nonwoven fabrics" are used for many purposes today. A fleece is prepared for their production, which is then sprayed or impregnated with a binder. Then you submit the so impregnated Fleece of a heat treatment, whereby the binding agent (e.g. latex) hardens or vulcanizes. The corresponding flat structure is then very elastic and can be used as a stiffening insert. Such products are generally known under the name VLIESELINE.

However, the nonwovens are also used for many other purposes used, e.g. as disposable towels.

For other purposes it is desirable to introduce a hole pattern into the end product. However, this is associated with a considerable outlay in terms of equipment. You have to put the fleece first on a sieve and then with a perforated plate such as shown in U.S. Patent 2,861,251.

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Then you shoot sharp jets of water through the holes in the cover plate. The water flowing through the holes with great force pushes the underlying fibers aside and then drips off through the sieve. This fleece perforated in this way is still not very stable and then has to be impregnated, which is also expensive in terms of equipment, in order to maintain strength.

It has now been found that perforated nonwovens of any pattern can be produced in the simplest way by first slurrying the nonwoven in a very large excess of water (about 1 part of fibers to 1000 parts of water) in a manner similar to that used in papermaking. The pulp is then sucked off on two perforated drums, as can be seen from the enclosed FIG. There the aqueous slurry of fibers reaches the settling chamber 2 via the feed pipe 1. Two drums are installed in the bottom of the latter. Each of these drums consists of a so-called sieve drum 3 or 3 ', which in turn is covered with an arbitrary pattern · + or 4 ¹ . The sieve drums 3 and 3 * correspond to the usual sieves in paper machines. The sieve drum 3 or 3 'can also be a galvanically produced finely perforated drum and the pattern drum ι + or 4' can also be a galvanically produced patterned drum.

At the left and right lower end of the settling space 2 elastic rubber lips 10 and 11 are arranged, which press ^{firmly against the surface of the rollers 3, «♦ and 3 ', 4 1.} This ensures that the water only runs off the surfaces of the rollers.

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Subsequently, a fine wire screen is then printed with, for example, PVC dots with a diameter of 2 to 3 mm, which are spaced about 5 mm apart. This one printed wire mesh is then completely drawn onto the sieve drum 3 once. The procedure is the same for the second screening drum 3 ', which can be covered with an identical or a corresponding pattern 4'. The drum 3 rotates clockwise in use, while the drum 3 'rotates counterclockwise. A vacuum is applied inside both drums, as a result of which the water from the heel chamber 2 is continuously drawn into the interior of the drum 3 or 3 ¹ . The fibers suspended in the water settle on the surface of the sample coatings 4 or 4 ¹ . It is interesting that the fibers are deposited almost exclusively in the uncovered areas. This leaves the places free where raised points are printed on the pattern. If these - as described above - are in the form of dots, then a perforated fleece is obtained on the pattern sieves 4 and 4 *. Perforated fleece is now deposited on the two surfaces 4 and 4 '. These are combined with each other at the point S, where the two drums touch. After passing through the nip 5, the combined perforated fleece from both drums is placed on a conveyor belt 6 which runs continuously around the rollers 7 and 8. Further dewatering of the initially still wet fleece takes place through the suction boxes.

When starting up, both rollers must be set so that they run in repeat. In this way it is ensured that a hole in the fleece lying on the surface 4 in the nip also strikes ^{a hole on the surface 4 1.} If this precaution is not observed, then of course the perforations would be overprinted again.

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According to the invention, £ ε thus finds a pattern or embossing of Nonwovens take place at the same time as their production. If you can run the rollers in a suitable manner in repeat, so can a Embossing can be achieved from the front and back.

If you let the apparatus run with a staggered repeat, the result is fleeces with raised patterns on both sides.

A repeat is produced in that the two rollers are connected with gears, as can be seen from FIG. II.

The perforated nonwovens arriving on the conveyor belt 6 can then be impregnated with a binding agent in the usual way will. During the subsequent heat treatment, the perforated fleece is stabilized in a known manner.

The binding agent (e.g. Acronal) can also be added directly to the pulp by precipitating it on the fibers and during Drying the fibers binds.

ORIGINAL INSPECTED

1098 13/1762

Claims (1)

Claims 1. A process for the production of perforated nonwovens, characterized in that staple fibers are slurried in water and the Fibrous pulp is sucked off via two contacting, counter-rotating, perforated, patterned rollers " 2 «device for the production of perforated nonwovens according to claim 1, consisting of a settling room 2, in the bottom of which two screen drums 3 and 3 * are installed, which in turn each with a sample drum 4 and U * are covered ] 0 ^ζ ! ■: 1 Ί '1 7 f.?