DE1660318A1 - Process for the production of spunbonded webs made up of heterofilaments - Google Patents

Description

CARL PREUDENBERG " ² ? ^{# 3} ^ i?

Weinheim / Bergstrasse CON 443 )

Process for the production of spunbonded nonwovens made of hetero filaments

This follows in the conventional manufacture of synthetic fibers actual spinning process, in which a so-called non-drawn paser is produced, the orientation process by mechanical means Stretching in which the thread is four to five times its Length is stretched. During this process, a molecular orientation occurs one that has a corresponding increase in strength and causes a reduction in the elongation at break of the finished thread. Furthermore, the thread must be prepared for the subsequent work steps by applying appropriate preparations and in many cases the smooth thread must be crimped, mechanically by means of gear or compression crimping is applied »

Recently, so-called heterofilaments have been used to an increasing extent manufactured in which lying side by side from the spinneret two different polymers are spun out, which already in the molten state become one of two components unite existing filament * These threads are spun out in the manner described above by mechanical stretching etc processed, particularly occur here

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in the mechanical stretching of particularly contradicting components Problems such as fanning out or separation of the various thread components on »These problems must be dealt with carefully mutual coordination of the spinning components can be overcome.

There are other tasks involved in the production of spunbonded nonwovens, since a flat structure is produced from the filaments to be deposited from the spinneret. As is further worked reasons of process technology with high spinning speeds (e.g. _e B _o 5000 m / min), "a post-treatment of the filaments by mechanical means prior to filing possible or only possible with considerable difficulties, it is therefore desirable, the filament already on the Seg to include as many of the desired properties as possible between the spinneret and deposit «In the case of molecular orientation, this is achieved by high distortion from the melt with a correspondingly fast freezing process The cross-section of the filaments as well as different quenching temperatures are achieved _e The mutual arrangement of the threads and their structure are of great importance, since the single thread immediately combines with its neighbors to form a flat, tangled structure, whose equilibrium t largely depends on the arrangement of the filaments specified on the spinning side »Furthermore, it was shown that the mutual» cohesion of the various fiber components can largely be controlled by the arrangement of the spinning holes, as will be explained in more detail below _o

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In the Swiss patent specification 403 149, a method for production described by spunbonded fabrics, in which sheets of threads are spun out of rows of holes lying parallel to one another in a straight line that with the help of several airflow pairs and Guide channels on a sieve belt with suction below be brought to storage. The advantage of this procedure is among other things «, in that the individual elements from the moment they are spun out to Formation of the spunbonded fabric remain separated from each other, so that a strand formation and mutual entanglement in front of the filing, the leads to fluctuations in grammage, is avoided «Another A considerable advantage lies in the straight line arrangement of the spinning holes. In contrast to the conventional shower head type Arrangement with a subsequent cable-like summary can be used for stretching and cooling with both sides of the Filament row attached air currents for each filament evenly take place. In the case of a round or cable-like arrangement the inner filaments always have different cooling effects exposed as ixe lying on the edge ..

In the production of spunbonded fabrics from heterofilaments, in which Filaments made up of "two or more different components like this are spun out so that the different material melts unite shortly before 'exit from a common spinning hole, It was found that not only the mutual arrangement of the spinning holes has an influence on the end product, but also the arrangement the currents of the various pools in relation to each other on the air currents used for stretching and cooling " This is due to the special type of fiber formation

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with the underlying S-pdnnvli.es method, - with - as above - the molecular orientation is not carried out by mechanical stretching one pre-formed Paser ,, but from the melt flow through a correspondingly high distortion with constriction of the still liquid filament and then quenched to freeze the orientation obtained takes place. Since the fiber-forming raw materials are largely in their freezing b.zw. Recrystallization behavior differ, it is understandable that when a certain air temperature is specified, the stretching or. Cooling air flows set different crystallization states for two different components. It is also understandable that by appropriate arrangement of the spinning holes and melt streams in relation to the air streams to be drawn a more or less strong interconnection of the various components within a heterofilament is achieved »

Fig. 1 shows a schematic cross section through an inventive Spinneret with downstream air duct

I or II is the spinneret (1) from two different melting units e.g. fed to extruders with downstream spinning pumps. The two melt streams merge briefly at point (2) before (e.g. 2 mm) leaving the spinning hole. Immediately after the Leaving the spinning hole is made up of the two components I and

II formed heterofilament to the left of one of the opening (3) and right 'detected by an air stream coming out of the opening (4) and introduced into the air duct (5). The air currents coming from the openings (3) and (4) are in the assigned supply channels (3a) and (3b) or (4a) and (4b) introduced and

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Speaking of the working method described in German patent application F 42 095 (.... ON335). In the air duct, the filament is still captured on the left by the air flow coming out of the hole (6) and on the right from the hole (7) and continues downwards torn to the catchment belt ,, The. The overall nozzle consists of a multitude of holes (e.g. 240) in a straight line Z ₀ B ₀ at a distance of 2 mm adjacent to each other, and the openings (3) and (4) b ,, between (6) and (7) are straight slits arranged parallel to the row of spinning holes, so that a row of straight filaments lying next to one another is formed, each of which is captured on the left and right by the air currents emerging from the slots F 42 095 (- «...... Note OH 335) and F 46 486 (" ο "... ο.Anm _o ON 372). Fig. La shows again the confluence of the two melt streams I and II shortly before the exit from the spinning locomotive.

In the production of spunbonded fabrics made up of heterofilaments is now the arrangement of the outflowing melt streams the filament components are important in relation to the air currents » This is particularly evident when the temperature of the air flows (3) and (6) is different from that of the air flows (4) and (7) is kept to be an asymmetrical deterrent received

Figure '2 shows a row of holes (8) with the both ends thereof mounted air slots (9) and (10) * The air slots (9) or (10), ■ would the slots (3) or ₀ (4) of Fig ₀ 1 correspond ., From the

Now a series of heterofilaments emerges from the row of spinning holes, which consist of compound I (hatched part) or II (light part) are introduced on both sides of the filament row "If the temperature of the respectively applied air flow _{pairs is kept different, Z 0} B ₀ - Tq) ^ io" ^{so er;} ^ hrt & i- ^e thread half I a treatment with air currents at a higher temperature than thread half II "This treatment can then be intensified by different temperatures of the air flow pair in the air duct (ie Z ₀ B ₀ T / -> T ₇ )" That is, the for Stretching leading to molecular orientation and also the freezing of this orientation by cooling takes place for thread half I under different conditions than for II, so that the stretching and freezing process can be modified for the various substances I and II. The arrangement of filaments in parallel in a row with the respective pairs of air streams of, spinning holes row is particularly advantageous to advantage when the supply of the melt of the various substances takes place within the spinning nozzle in such a way - ₉ characterized in that the arrangement of the substances in the yarn cross-section in a similar manner in Reference to the airflow slots and thus the different partners of the airflow pairs takes place _a

Achieving maximum voltages can cause desired for many products maximum crimp of the filaments "The generation of voltages z" B "can be caused by the fact that the filament constituting substances I or _a II chemically greatly different from each other sindj Z ₀ B ₀ can I a polyamide such as nylon

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and II be a polyester, for example polyethylene terephthalate. During melt spinning, both substances are free of water. However, after spinning, polyamide (nylon 6) absorbs enough moisture until its equilibrium water content of about 4.1 / o (at 65% relative humidity) is reached. Polyester (polyethylene terephthalate), on the other hand, has a moisture absorption of approx. 0.4 $ under the same conditions. Since the absorption of moisture causes the fiber substance to swell, the parallel change in dimension causes the threads to crimp occurs, there is a strong felting of the fiber structure.

In many cases, especially when the spunbonded fabrics produced in this way should be solidified by applying additional binders, if it is an advantage to enlarge the thread surface by spinning out profile holes, there are better points of attack for binding agents to have"

Fig. 3 shows schematically such an arrangement of double semicircular Profile holes, again a substance I (black half) and another substance II (white half) to a pro

Heterofilierte XXBfiifaden, is spun. In the case of such profile holes, especially when spinning heterofilaments, the arrangement of the air currents coming from the slots (11) or (12) plays a role _{or the like}

In Fig. 4 the arrangement of the profile holes is chosen so that both ends of the filament substance I and II face the same air flow. In the arrangement shown schematically _{in Fig c 3}

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only side I inclines towards the air flow coming from (11). Since the air currents spread out at an angle of 15 ° after leaving the air slots, a force facing the filament row is exerted, which is indicated by the arrows 13 and 14; dch ₀ in the arrangement of Fig. 3 the filament sides 1 are pressed onto the filament sides II, while the opposite effect occurs in the arrangement of Fig. 4, The practical importance of this process is now to obtain the greatest possible increase in tension If, for example ,, φ as described above, the substances I and II at different as nylon and polyester widely, an arrangement according to Fig _o 3 may cause that the two contrary substances are welded to a greater distance of the filament to each other by the influence of the Air currents 13 and 14, which, due to the mutually different character of substances I and II, produce a filament with strong tensions and thus possible crimps. The arrangement shown in Fig. 4 is advantageous when substances similar in their chemical properties are to be spun . This is the case, for example, when one uses heterofilaments

made of nylon 6 and nylon 66, or one made of polyethylene terephthalate and one made of copolyester made of terephthalic acid / isophthalic acid or terephthalic acid / paraoxybenzoic acid. Due to the difference in softening temperature, such mixtures can often be used to produce binder-free spunbonded nonwovens, with the low-melting filament component Binder Z ₀ B, which is used for heat strengthening

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can be increased that the spinning arrangement mentioned in Fig. 4 is selected, with the _{air streams coming from the slots 11 or p} 12 having different temperatures from one another. As a result, both the thread sides I and II facing the air flow coming from slot II are subject to a different cooling mechanism than the thread sides I and Ho coming from slot 12 Compared to a calender treatment, autogenous welding has the advantage of avoiding a paper-like compression of the sheet-like structure. Continue to be through. the steam treatment at the same time as the solidification

in the
ripples or »shrinkage» sber -moisture atmosphere

tensions latent in the fiber are released, ',.

It has been shown that the exerted by the air currents Forces can be used to shape the cross-section of the filaments produced by welding, as shown in Fig. 5 emerges »Here a C-shaped profile has been chosen ^ its open Side in a uniform arrangement one after the other towards the nozzle end looked through the forces of the slots (11) or, (12) coming air currents, which act in direction 13 or »14, will be the C-shaped cross-section of the filaments closed, making a heterofilament with a hollow cross-section as shown in Fig. 5a.

The arrangement of the spinnerets or rows of spinning holes described in German patent applications F 48 397 ( * ... ».. ON 400) and F 48 438 (. _Tt » ....... "ON 401) for the purpose of appropriate mixing of the

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Filaments within the spunbonded nonwoven by spinning out various combinations should also apply within the scope of the present application, i.e. in the case of very long spinnerets, e.g. 500 holes / nozzle, the start holes of the row can spin different heterocombinations than the end holes of the row. This is indicated in Figure "2, where the holes 15 other polymer combinations are supplied as the holes 16 _o This is at 500 holes a length of about 1 m have at such long nozzles z _e B _o, easily by dividing this nozzle in To achieve single segments and separate enamel feeds. The fiber products that can be manufactured using this technology are characterized by a particularly round and supple handle. This is particularly important in the production of thicker fiber mats, which are then _{to be further processed into leather-like synthetic products by impregnation with fiber-binding substances Z 0} Bo through coagulation of high polymers within the fiber structure. A further procedure here is that one component of the he terofilaments is dissolved out in order to create pores within the fiber structure, if, for example, component I of the heterofilaments is made from nylon 66 and component II is made from a copolymer of polyamide from caprolaetam, adipic acid, hexamethylenediamine , the latter filament component can be dissolved out with alcohol. Other combinations of this type, such as, for example _, sparingly soluble polyethylene terephthalate and soluble copolyesters made from terephthalic acid, isophthalic acid or polypropylene with easily soluble polystyrene, are well known to the person skilled in the art and do not need to be listed in detail.

Another product group made with the help of this novel technology have experienced a significant improvement in their properties

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textile-like spunbonded fabrics, such as those used as outer fabrics. In these textile-like spunbonded nonwovens, which are also impregnated with fiber-binding high polymers such as ZiB ₀ polyacrylic esters to achieve maximum abrasion and pilling resistance, it is also important to have a particularly round handle with maximum tear and tear resistance and the best possible abrasion resistance Particularly favorable combinations for this field of application are the combination of ζ " _{β β} polyamides with polyesters. Experience has shown that it is difficult to bind nonwovens consisting of 100% polyester fibers so tightly that a washing and cleaning resistance that is satisfactory for textile purposes On the other hand, the properties of polyester fibers such as ζ.Bo their high resistance to light would be very desirable in the manufacture of textile-like outer fabrics ,, The polyamide fibers on the other hand can be bound very well due to their high affinity for the common high-polymer binding substances "By combining both substance In the form of heterofilaments, a top fabric-ready spunbonded nonwoven with good light resistance and excellent strength can be produced.

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Claims (5)

Patent claims: 1) Process for the production of composed of heterofilaments Spunbonded fabrics by feeding different melt streams into a spinneret and bringing them together Melt streams shortly before emerging from the spinning hole, so that both components in the form of a heterofilament from the Exit spinning hole, characterized in that the FiIa- ^ ments spun out in rows in a straight line and with the help ₌ air currents applied to both sides of the rows are stretched and solidified, the filament components being aligned in the same direction within the row with regard to the arrangement of the air currents. 2) Method according to claim 1, characterized in that in each case the same fiber component of a row is the same Airflow is turned off * 3) Method according to claim 2, characterized in that both fiber components of a row are turned towards the same air flow ₀ 4) Method according to claim 1, characterized in that Filaments are spun from semicircular profiles, which are spun with the help of the row of spinning holes on both sides attacking air currents are deformed into hollow fibers. 5) spunbonded fabrics produced according to claims 1-4, "009810/16 5 2 Blank