DE2053076A1 - Method for impregnating fiber vheses with liquid or foam-like binders and device for this - Google Patents

Description

Carl Freudenberg Company October 27, 1970

Weinheim / Bergstrasse Dr.Z / Sn - ON 564

Process for the impregnation of nonwovens with liquid or foam-like binders and device therefor

You impregnate loose fiber fleeces (which are produced e.g. by means of a carding machine or a Randow weaver) with liquid binder compositions such as synthetic or natural latices or curable synthetic resin emulsions or dispersions and dries and if these impregnated fleeces are then vulcanized or condensed, textile or paper-like flat structures are obtained, which are known as nonwovens or according to the English designation "nonwovens" or "nonwoven fabrics" are.

The impregnation of the nonwovens can be done in the simplest case by spraying with a binder solution. This method however, it is very cumbersome and time consuming. It has therefore already been proposed that the fleeces with wire screens on the upper and lower surfaces to cover and to pass them in this state through an impregnation bath. Corresponding devices are in the Book "Texti! Verbundstoffe" by Dr. Radko Krcma, VEB Fachbuchverlag Leipzig, 1963, page 163. It was found, however, that with this type of impregnation, the meshes of the wire screens can be blocked by both fibers and binders. In addition, especially in the case of thick nonwovens, there is no uniformity To achieve impregnation.

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In order to avoid these disadvantages, the so-called foam impregnation method was used suggested. Here, the fleece is shown in FIG. 1 of German Auslegeschrift 1 232 5tt, for example introduced the gap of a horizontally arranged pair of steel rollers. At least one surface of this pair of steel rollers is in this case, corrugated with a pattern roughly corresponding to FIG. 2 of the aforementioned Auslegeschrift.

In this process, the binder itself is first converted into foam form and then into the upper part of the gap introduced, which exists between the two rollers. In this way, the foam is pressed directly and evenly into the fleece.

It has now been shown that this process can be improved again if one uses a pair of steel rollers that are not Has embossments, but a so-called. Sawtooth profile of the following described type.

To generate such a sawtooth profile on a roller it is sufficient to produce a flat band, the surface of which is toothed, as can be seen from FIG. la. The dimensions are drawn to scale. But the teeth can too have different dimensions. Figure Ib shows a perspective Side view of another tape.

The tape is wound around a roller so that the upright Side edges of the tape touch each other. In other words: A closed surface is then formed from which only the saw teeth protrude.

FIG. 2 shows schematically how the wire 1 is wound onto the roller 2 will.

FIG. 3 shows schematically a roller pair according to the invention, in which the roller 2 is provided with saw teeth.

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So these saw teeth are not symmetrical in the sense that it is the figure Ic shows, but asymmetrically as symbolized by the figures la, Ib and Id. So there are directed saw teeth before, which can also have curved shapes.

When the impregnation roller mill according to FIG. 3 is put into operation, the rollers 2 and 3 each rotate in the direction shown in the rollers Directions of arrows. The saw teeth point (with roller 2) in a direction opposite to the direction of rotation of the roller.

The counter roller 3 is arranged as close as possible to the surface of the roller 2. However, there is still no direct contact with the Surface of the roller 3 with the teeth of the roller 2 instead. During the impregnation, a fiber fleece 4 is left in a manner known per se With the help of a slatted frame 5, run onto the surface of the saw teeth of the roller 2 Binder 6 too.

The roller 3 now presses the foam-like binding agent into the fleece H as it passes through the roller gap. The surface of the roller 3 can be smooth or also have a weak gravure. The surface of this counter roll can be made of steel or have an elastic rubber coating.

After passing through the nip, the impregnated wet fleece can be removed easily and without the slightest distortion Remove the teeth of roller 2. However, this is only the case if the teeth are opposite to the direction of rotation of the roller. If the teeth point in the wrong direction, then you have the same difficulties as when using a smooth roller 2, i.e. the wet fleece now sticks to the surface of the roller 2 and winds up on it.

However, continuous operation is only guaranteed if if the wet fleece is after passing through the

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The nip immediately detaches from the surface of the roller 2, then runs about a quarter turn along the surface of the roller 3 before it now again moves away from the surface of the Roller 3 must separate easily. The fleece then runs into a hot air chamber. There takes place drying and subsequent Vulcanization or curing of the binder takes place.

If very thick fleeces have to be impregnated, a method according to FIG. U is recommended. A pair of rollers is now used in which the surfaces of both rollers are toothed. In this case, the fleece to be impregnated now runs from above directly into the roller gap. It no longer runs, as in the embodiment according to FIG. 3, onto the uppermost point of the roller 2 and then remains a quarter turn on the roller surface before it runs into the gap.

In the embodiment according to FIG. H, the foam 6a and 6b are pressed into the fleece from both sides. In this case, too, the saw teeth must in each case against the respective Show the direction of rotation of the rollers in order to ensure perfect, distortion-free removal from the roller surfaces.

When the nonwovens are impregnated with one or more toothed rollers, not only is there a uniform distribution of the "Binder in the fleece as well as easy detachment of the wet fleece from the roller surface | the method according to the invention is also advantageous because with a single toothed roller, nonwovens of different thicknesses with the various binders can be impregnated.

On the other hand, if you impregnate with an engraved roller according to the German Auslegeschrift 1 232 5 ^, then you get the depth of the Engraving must adapt to the thickness of the fleece and the binder currently being used. The nonwovens manufacturer,

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who works according to the German Auslegeschrift 1 232 544 is required that is, several rollers with different engravings, while according to the invention one roller is sufficient. Also kick Naturally, when working for a long time, there is also damage to the surfaces of the rollers. But one day it will be the engraving of a roller damaged according to German interpretation I 2 32 5M-4-, so must a new roller must be procured. When working with the sawtooth roller on the other hand, only the old tape and a new tape with sharp teeth is then removed at the damaged area raised. Incidentally, the production of one is according to the invention Saw tooth roller considerably cheaper than that of an engraved roller.

example

_{A V 2} A steel belt with straightened teeth is drawn onto the unmachined surface of a steel roller with a length of 2400 mm and a diameter of 300 mm. The height of the band from the base to the start of the serration was 1.55 mm. The height of the teeth themselves was 0.7 mm. The band had about 14 teeth over a length of one centimeter. The thickness of the tape was 0.7 mm.

The wire is wound up tightly around the roller so that the side edges touch.

Now you arrange another roller at the same height opposite the toothed roller, which has a smooth steel surface having. Both rollers are pushed so close together that a gap of only 0.1 mm is created.

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2. Production of the fiber fleece £

Prepare a mixture of thin cardable fibers of the following composition:

Wt%

Wool 10 Human hair 10 Camel hair 15th cotton 20th Rayon

From this mixture by means of carding batts to produce a thickness of about ₁ mm O H. The weight of a pile is about 30 g / m. With the help of a cross-layer, six such piles are now placed on top of one another. The resulting high-volume fiber fleece is pressed between hot rollers and subjected to a slight distortion in the longitudinal direction until a weight of about 170 g / m 2 results.

First you prepare the following latex mixes:

liquid
Parts by weight fixed
Parts by weight Butadiene styrene (60%) 167 100 Distilled water 86 Sodium isobutyl naphthalene
sulfonate 15th 15th

Ultra-vulcanization accelerator (zinc-dimethyl-dithiocarbo-

nat) 20% 5

Zinc oxide dispersion HO% 15

Sulfur dispersion 25% strength 10 2.5

Antioxidant 60% 2 1.2

300

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This dispersion is now in an Oakes mixer for so long stirred until a foam is formed which contains 5 parts by volume of air per part of liquid.

The fiber fleece produced according to point 2 is with the help of a slatted frame 5 in the manner shown in Figure 3 to close brought up to the toothed surface of the rolling mill according to point 1. The two rollers rotate in opposite directions Sense, wherein the teeth of the roller 2 are opposite to their direction of rotation.

The foamed binder produced according to point 3 is then placed on the surface of the fleece in the remaining gap between the two rollers. After impregnation, the wet web is allowed to run into a drying chamber whose temperature is approximately between 80 and 120 ⁰ C. At this temperature itself there is practically no vulcanization of the binder. In order to achieve this, the temperature is increased to 120 to 140 ^° C. in part of the dryer. The fleece is then calendered under slight pressure and then washed again with warm water in order to wash out soluble residues during the impregnation.

The fleece obtained in this way is extremely uniform the binder distribution.

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Claims (2)

- ο - Claims (ΐϊ Process for impregnating fiber fleeces with liquid or foam-like binding agents by pressing the latter into the fleece using a pair of rollers, characterized in that at least one roller has a toothed surface, the teeth being aligned against the direction of rotation of the roller, 2. Device for impregnating nonwovens with liquid or foam-like binders, consisting of a pair of rollers, in which at least one surface of the roller is toothed. 209819 / 08Ai