EP0846197B1 - Process for producing a high-strength, high-shrinkage polyamide 66 filament yarn - Google Patents

Abstract

A nylon 66 filament yarn having a tenacity of at least 60 cn/tex, an elongation of 10 to 25% and a hot air shrinkage of 7-11% (160 C).

Description

The invention relates to a method for manufacturing a high-strength, high-shrinkage polyamide 66 filament yarn for industrial fabrics, in particular Airbag fabric, by multi-stage stretching of Polyamide-66-LOY using at least three heatable Stretching roller units or godet duos and immediate winding of the drawn yarn into one cylindrical package 'in particular to a Cheese and a polyamide 66 filament yarn.

For winding up shrinking thermoplastic Filaments are usually copse used, giving them one for further processing cheaper protective twine is issued. The disadvantage of Cops, however, is that the maximum Winding speeds in the range of just a few are a hundred meters per minute. Another disadvantage The cops rewinder is that the yarn capacity a stretch cop generally limited to approx. 4 kg of yarn is. Economic yarn production is after one such procedures are no longer guaranteed. The immediate winding of shrinkable yarns too cylindrical coils would be desirable. But it is Previously not possible to use yarns made of thermoplastic Wrap up polymers with high thermal shrinkage. Such Yarns have to be an undesirable reduction in the To prevent thermal shrinkage, under relatively high ones Thread tensions are wound up. This has serious consequences Disadvantages on the coil structure. As a result of the high Thread tension is so high inside the package Radial forces that deform the coil sleeves on the one hand so that the full spools are no longer from the thorn of the Can be removed. Another Disadvantage, on the other hand, is that intolerable Wrapping deformations are observed that are building up full of coils impossible.

DE-A-34 37 943 describes a process for the production known from polyamide 66 filament yarn, where the yarn has a high strength, a high Elongation and low shrinkage and that, in contrast to yarns with one high shrinkage, can be wound on packages without problems. The suitable device consists of several heated stretching roller units. To improve the Drawability of the yarn also becomes sources of heat in the form of contact heaters between the stretching rollers intended. It is known that when Melt spinning process, at a winding speed of 4500 m / min and above, the winding tension so is increased that a paper spool of the winding machine is not more can be removed. The problem with this Procedure solved by relaxing by about 10%. For the No winding of the drawn yarn is given made. The well-known yarns are at speeds of a maximum of 20 m / min. Aim of the known Process is the production of so-called dimensionally stable filament yarns for tire cord fabrics, with high strength, high elongation and a low Shrinkage, if possible below 5%. For these yarns they are Stretching conditions and especially the winding conditions optimized on packages.

Recently, however, specifically for use in Airbag fabrics, increasingly also yarns with high Thermoshrink used. Such types of yarn can be not difficult to create, but they can not be without Wind up problems on packages.

The object of the invention is a high-strength, high shrinking polyamide 66 filament yarn to manufacture, which then follows the Can stretch directly on packages.

Another job is to do both Production speed as well as the unit weight the thread carrier and thus the economy of the To increase the stretching and winding process. Facilities for Allow generation of cylindrical cheese Production speeds of several thousand meters per minute.

According to the invention, the object is achieved in that at a relaxation ratio of 4 to 10%, the Temperature of the last stretching roller unit before Winding between 70 ° C and 160 ° C, especially 80 ° C and 150 ° C, preferably to 90 ° C - 140 ° C and the Winding tension to less than 0.2 cN / tex, especially to less than 0.15 cN / tex, preferably less than 0.13 cN / tex can be set.

The thread tension in the winding area essentially becomes by the relaxation ratio, i.e. by the Ratio of the speeds of the last Stretch godet and the winding device determined. It is expedient, the relaxation ratio between 4 and 10% to choose.

At a temperature of the last stretch godet of less than 70 ° C is a perfect coil structure practically not possible At a temperature of over 160 ° C the thread tension in the winding area becomes so high that also no perfect cross-wound bobbins can be produced, or the thermal shrink becomes so deep by lowering the thread tension that no shrinking yarn can be obtained more.

For an acceptable coil build of a cylindrical one The cheese is only a narrow area of the thread tension allowed. With a winding tension greater than 0.2 cN / tex an acceptable coil structure is no longer possible. The Cross-wound bobbins form high beads on the side edges be pressed flat by the driving roller. As As a result, the flanks of the coils are turned outwards pressed so that they finally flank the Protrude from the thread carrier. Such coils can not only be do not pack and ship properly, they result also significant difficulties in the subsequent Processing of the yarn, whereby thread breaks often occur. In the opposite case, the winding tension becomes too low chosen, e.g. less than 0.05 cN / dtex, then it will Yarn package very soft. It doesn't have enough interior Cohesion so that it doesn't ship well either and let it work.

Since winding machines for the production of cylindrical Cross-wound bobbins in contrast to conventional ones Cops winding speeds of several thousand Enable meters per minute, it is appropriate and economical, stretching into one Integrate spin stretching process.

The polyamide 66 filament yarn shows a relative Viscosity (RV) of> 40, measured in 90% Formic acid according to ASTM 0789-81, a strength of at least 60 cN / tex, an elongation of 10-25% and one Thermal shrinkage of 7-11% at 160 ° C and is one Cross-wound bobbin with at least 6 kg thread mass. It is surprisingly successful, such a shrinking Polyamide yarn to 6 kg spools instead of uneconomical copse with a maximum of 4 kg Capacity.

The polyamide 66 filament yarn according to the invention is for industrial fabrics, in particular for airbag fabrics suitable, which besides high strength also should have a particularly high thermal shrinkage.

Fig. 1 schematisch das erfindungsgemässe Verfahren

Fig. 2 schematisch eine Variante des erfindungsgemässen Verfahrens,

The process according to the invention is to be described in more detail with the aid of a process sketch. Show it:

Fig. 1 shows schematically the inventive method

2 schematically shows a variant of the method according to the invention,

In Fig. 1, reference numeral 1 is an undrawn one Designated polyamide-66-LOY filament. The filament is from a delivery roller, not shown, to a first one heated stretching roller unit 2 fed. Between the Delivery roller and the first stretch roller unit 2 is slightly stretched undrawn filament 1 by approx. 3%, to give the filament 1 a minimal tension. The Thread tension must be selected so that a sufficient adhesion between filament 1 and guaranteed the surface of the stretching roller assembly 2 is the one that occurs in the first drawing stage Stretching force to provide the required resistance. Between a second heated to about 180 ° C Stretching roller unit 3 and the first stretching roller unit 2 a first drawing takes place. A third stretching roller unit 4 with a The surface temperature is from 70 ° C to 150 ° C heated stretching roller unit 3 and causes another second stretching.

After drawing, the drawn filament 5 is opened a cheese 6 wound. To humiliate the Thread tension becomes the filament at a speed spooled, which is set about 6% lower than the speed of the aggregate 4. The winding tension is thereby set to, for example, 0.13 cN / dtex. All drawing roller units are from the filament 1 wrapped several times around, on the one hand the necessary Ensure frictional connection for stretching and around on the other hand, an adequate heat exchange between the heated roll surfaces and the filament 1 guarantee.

Fig. 2 differs from Fig. 1 by a Additional stretching roller unit 7. When moving to In this variant, the stretching roller unit 7 for example heated to a temperature of 180 ° C. In In this case, the second stretch between the Stretching roller units 3 and 7 carried out during the Temperature of the stretching roller unit 4. compared to Arrangement in Fig. 1 is not changed. The The speed of the stretching roller assembly 4 is there at least as high as that of the Stretching roller unit 7.

The device according to FIG. 1 is exemplary and not only suitable for performing the procedure. A device suitable for the method can instead of the stretching roller units with separating rollers also consist of godet duos. Furthermore, between the units further elements for thermal Treatment of the yarn such as block or radiant heaters, Hot air or steam nozzles can be arranged. Further is it is expedient to use a Whirl air nozzle or the like to thereby the Improve processability.

This device is also not for just one Filament thread suitable for finer yarns, for example with a titer of 470 dtex or less, can also use two or more filament threads at the same time stretched and on a correspondingly multi-ended Be wound up.

The operating speed of this device is in the Range between 300 and 3,000 m / min. It is therefore much more productive than conventional draw twisting machines, who put the thread on cops. Can also Cross-wound bobbins with a thread mass of more than 10 kg getting produced. Opposite the cops makeup with a maximum of 4 kg is much less Manipulations required. The high working speed does not limit the usability on the stretching of already wound LOY filament yarns on. In principle, it is also for the Use in an integrated spin-stretch process suitable.

Usually high strength yarns with low Thermal shrink relaxed before winding. This generally happens through the use of a additional godet unit, which by one defined amount runs slower than the last A draw roller unit. But it is also possible that Thread shortening immediately within the winding area by making the winding with a slower speed than that of the last stretch godet.

To create a shrinking yarn in the Contrary to the conventional technique the relaxation of the Yarns are prevented as far as possible. So it will be Task to provide a process that a if possible unrelaxed yarn is wound up. Theoretically leaves accomplish this by Speed of the winding unit equal or only is slightly slower than the last one Godet unit. But this has very high thread tensions result, among which the construction of a package in general is not possible.

The procedure is further based on the following Examples explained.

Example 1 (comparison)

A LOY filament yarn made of polyamide 66 with a relative Viscosity (RV) in formic acid of 45 and one Spinning titer of 1,270 dtex was doubled over the Device guided according to Figure 1. The filament yarn was under the conditions given in Table 1 in two stages in a ratio of 5.3: 1 to the titer 235 dtex stretched and within the winding zone, i.e. between the Stretching roller unit 4 and the package 5 by 6.8% relaxes. The temperature of the last stretcher was 230 ° C. The filament yarn obtained had one Strength of 74.5 cN / dtex with an elongation at break of 22 % and a thermal shrinkage at 160 ° C of 3.6%. It is however for special applications, e.g. for the area Airbag fabric not because of the low thermal shrinkage suitable.

Example 2 (comparison)

A LOY filament yarn made of polyamide 66 with a relative Viscosity (RV) in formic acid of 45 and with one for Airbag fabric suitable high thermal shrinkage was under the essentially same stretching conditions as in Example 1 achieved in that the temperature of the last stretch godet was reduced to 160 ° C. The Relaxation ratio was compared to Example 1 slightly reduced to 5.7%. The yarn obtained showed a strength of 72 cN / tex with an elongation at break of 16.6% and a thermal shrinkage at 160 ° C of 9.2% on.

The intolerable disadvantage of this procedure, however, was in that by lowering the temperature of the last stretch godet the thread tension in the winding area with 0.38 cN / dtex was so high that no acceptable Coils could be built. Already after 1.5 kg Thread support, the bobbins were so deformed and on the flanks bulged out that they are the bearers serving thread tubes protruding on both sides. Such Coil is for shipping as well as for the Processing, e.g. unsuitable in a weaving mill.

Example 3

A LOY filament yarn made of polyamide 66 with a relative Viscosity (RV) in formic acid of 45 with one for Airbag fabric suitable high thermal shrinkage was under the essentially same stretching conditions as in Example 1 achieved in that the temperature of the last stretch godet was lowered to 105 ° C. The Relaxation ratio was compared to Example 1 slightly reduced to 6.5%. The yarn obtained showed a strength of 74.2 cN / tex at one Elongation at break of 17.4% and a thermal shrink 160 ° C from 9.0%. The thread tension in the winding area surprisingly amounted to only at this setting 0.13 cN / dtex as in Example 1. This way Cross-wound bobbins with 7.5 kg thread support without any problems getting produced. The aspect of these coils was good: the Flanks were straight and there was none on the circumference of the coil Watch shoulder formation.

Example 4

Two PA 66 filament yarns with a starting denier of 2,540 dtex were two-stage with one as in Example 3 Stretch ratio 5.4 stretched. The temperature of the The stretching roller assembly 4 was lowered to 90 ° C. at a relaxation ratio of 7.5% was one Thread tension in the winding area of 0.074 cN / dtex measured. The bobbins contained a yarn mass of 10.3 kg and were flawless with straight flanks and without Shoulder formation on the circumference. The stretched thread pointed the properties given in Table 1.

The following Table 1 shows the process parameters according to the method according to the invention, with stretching on a stretching machine with three heated stretching roller units, godets with separating roller in two stages at 800 m / min final speed to 5.4 times its initial length. The thread properties are given in the same table. example 1 2 3 4 Process parameters: bad Stretching speed [m / min] 800 800 800 800 Temp. Last godet [° C] 230 160 105 90 draw ratio 5.3 5.4 5.4 5.4 Relaxation ratio [%] 6.8 5.7 6.5 7.5 Winding tension [cN / dtex] .13 .38 .13 .074 Thread mass per bobbin [kg] 7.5 1.5 7.5 10.3 Coil construction: Good bad Good Good Properties of thread: Titer [dtex] 235 235 235 470 Strength [cN / tex] 74.5 72.0 74.2 74.2 Elongation at break [%] 22 16.6 17.4 18.7 Thermal shrink 160 ° C [%] 3.6 9.2 9.0 9.3

The device according to the invention has compared to the known devices two major advantages. It On the one hand, two or more threads can be used at the same time can be stretched and wound up and on the other hand can the production speed because of the compared to more efficient winding on packages the conventional drawing twine can be increased. The Yarn according to the invention is particularly suitable for the production of Airbag fabrics suitable.

Claims (4)

1. Process for producing a high strength, high shrinkage nylon-6,6 filament yarn for industrial fabrics, especially for airbag fabrics, by multistageddrawing of nylon-6,6 LOY filament (1) having a relative viscosity RV of at least 40 by means of at least three heatable draw roll assemblies (2, 3, 4, 7) and directly winding the drawn yarn (5) onto a cylindrical yarn support (6), characterized in that with a relaxation ratio of 4 to 10%, the temperature of the last draw roll assembly (4) prior to the wind-up is set to between 70°C and 160°C, and the winding tension is set to less than 0.2 cN/tex.
2. Process according to Claim 1, characterized in that the drawing is an integral part of a spin-draw process.
3. Process according to Claims 1 and 2, characterized in that the wound cheese produced comprises at least 6 kg of yarn.
4. Nylon-6,6 filament yarn for industrial fabrics, characterized in that the nylon-6,6 filament yarn has a tenacity of at least 60 cN/tex, an elongation of 10 to 25% and a thermal shrinkage of 7-11% (160°C) and has been wound onto the cheese comprising at least 6 kg of yarn.

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