EP2171138B1 - Spinning method - Google Patents

Description

The present invention relates to a method of spinning a multifilament yarn of a thermoplastic material, comprising the steps of extruding the molten material through a plurality of nozzle holes of a spinneret into a multifilamentary filament bundle and wound up as a multifilament yarn after solidification, and wherein the Filament bundle is cooled below the spinneret.

Furthermore, the present invention relates to multifilament yarns, especially polyester multifilament yarns and cords containing such polyester filament yarns.

A method as described above is known from WO 2004/005594 known. In this case, the filament bundle is cooled below the spinneret in two stages, the filament bundle is cooled below the spinneret in a first cooling zone first by means of a Queranblasung by a gaseous cooling medium and by means of a Queranblasung opposite suction of the gaseous cooling medium, and then in a second cooling zone below the first cooling zone, the filament bundle is substantially further cooled by Selbstansaugung located in the vicinity of the filament bundle gaseous cooling medium. Although that causes in the WO 2004/005594 described method effective cooling of the extruded filaments.

However, there is a need to be able to spin a multifilament yarn having a high total titer, a dimensional stability at least as good as the dimensional stability of the process of WO 2004/005594 resulting yarns, and has an acceptable running behavior.

The term "dimensional stability", which is abbreviated to Ds below, means the sum of the elongation of the yarn in% after application of a specific force of 410 mN / tex ("elongation at specific tension") EAST and hot air shrinkage ("hot air shrinkage"). HAS in% at 180 ° C, a preload of 5 mN / tex and over a measurement period of 2 minutes, ie Ds = EAST + HAS, where HAS means the absolute value of the hot air shrinkage.

Further, the term "running behavior" includes the number of lint per 10 kg of yarn and the number of yarn breaks per 1000 kg of yarn.

Therefore, the object of the present invention is to provide a process by which a multifilament yarn can be spun from a thermoplastic material having a high total titer, a dimensional stability at least as good as the dimensional stability of those obtained by the process of WO 2004/005594 resulting yarns, and has an acceptable running behavior.

This object is achieved by a method of spinning a multifilament yarn of a thermoplastic material comprising the steps of extruding the molten material through a spinneret into a multifilamentary filament bundle and wound up as a multifilament yarn after solidification, the spinneret having a plurality of nozzle holes and the ends of the holes at which the filaments emerge form a nozzle hole exit plane, and wherein the filament bundle beneath the spinneret is cooled in a first cooling zone first by at least one transverse blowing through a gaseous cooling medium and by means of a suction of the gaseous cooling medium opposite this transverse blowing , and then in a second Cooling zone below the first cooling zone, the filament bundle is further cooled by Selbstansaugung located in the vicinity of the filament bundle gaseous cooling medium, characterized in that in the first cooling zone, the at least one Queranblasung the gaseous cooling medium via a Anblasstrecke AC of length L, wherein the Anblasstrecke AC an upper end facing the nozzle holes A and a lower end facing away from the nozzle holes C, and the Anblasstrecke AC opposite a distance BD is arranged, which has a nozzle holes facing the beginning of B and facing away from the nozzle holes end D, and between A and B imagined distance AB is parallel to the nozzle hole exit plane, wherein the distance BD has the length L, and wherein the distance BD is divided into an open suction distance BX of length L _BX , through which the gaseous cooling medium is sucked off, and into a closed draw e XD of length L _XD , where the ratio L _BX : L _{XD is} in the range of 0.15: 1 to 0.5: 1.

With the method according to the invention, it is surprisingly possible without any bonding to spin filament bundles of thermoplastic material directly from the spinneret ("direct spinning") whose total titre is 1800 dtex and above, the running behavior, ie the number of lint per 10 kg of yarn and also the number of yarn breaks per 1000 kg of yarn is significantly smaller than in a multifilament yarn whose in WO 2004/005594 described manufacturing method differs from the method according to the invention only in that in the first cooling zone, the suction of the gaseous cooling medium over the entire length BD = L takes place. Further, the dimensional stability of the resulting multifilament yarn, Ds = EAST + HAS, is at least as good as Ds of the yarns made from the inks WO 2004/005594 described methods result.

Even when spinning multifilament yarns with a total titer below 1800 dtex, the inventive method improves the quality of the spinning process in comparison to in WO 2004/005594 described method in the form of a significantly reduced number of lint per 10 kg of yarn and also clearly smaller yarn breakage per 1000 kg of yarn with at least equally good dimensional stability.

In order to realize the aforementioned advantageous effects of the method according to the invention, it is essential to the invention that the distance BD is subdivided into an open suction path BX of length L _BX , via which the gaseous cooling medium is sucked off, and into a closed path XD of length L _XD , wherein the ratio L _BX : L _{XD is} in the range of 0.15: 1 to 0.5: 1.

• entweder zu einer derart intensiven Verklebung der Filamente, dass es vollkommen unmöglich ist, ein Filamentgarn mit einem Gesamttiter von 1800 dtex oder gar darüber zu spinnen (Schwarz-weiß - Effekt)
• oder das Spinnen eines Multifilamentgarns mit einem Gesamttiter von 1800 dtex oder darüber ist zwar durch Absenkung des Streckverhältnisses möglich, liefert aber ein Multifilamentgarn mit inakzeptabel hohen Werten der Flusenzahl pro 10 kg Garn und der Fadenbruchzahl pro 1000 kg Garn. Zudem besitzt das Garn eine zu geringe Dimensionsstabilität, d.h. einen zu großen Wert von Ds = EAST + HAS.

If the distance BD is not subdivided into an open suction path BX of length L _BX and into a closed path XD of length L _XD , so that the suction takes place in the first cooling zone over the entire length BD = L, then the process conditions are otherwise the same

• either to such an intensive bonding of the filaments that it is completely impossible to spin a filament yarn with a total titre of 1800 dtex or even more (black-and-white effect)
• or spinning a multifilament yarn having a total denier of 1800 dtex or above is possible by lowering the draw ratio, but provides a multifilament yarn having unacceptably high values of the number of curls per 10 kg of yarn and the yarn breakage number per 1000 kg of yarn. In addition, the yarn has too low a dimensional stability, ie too large a value of Ds = EAST + HAS.

At a total titre below 1800 dtex, it is true that a filament bundle can be spun even with an extraction line open over the entire length BD = L. However, under otherwise identical conditions as in the method according to the invention, the number of lint and the number of yarn breaks is significantly higher than in the process according to the invention.

According to the invention, the ratio L _BX : L _{XD is} in the range of 0.15: 1 to 0.5: 1. At a ratio L _BX : L _XD which is smaller than 0.15: 1, the cooling effect exerted on the filaments is insufficient and it comes to the bonding of the filaments. At a ratio L _BX : L _XD , which is greater than 0.5: 1, no sufficiently stable running behavior is achieved.

In a preferred embodiment of the process according to the invention, the ratio L _BX : L _{XD is} in the range from 0.2: 1 to 0.4: 1, more preferably in the range from 0.25: 1 to 0.35: 1, and very particularly preferably in the range of 0.27: 1 to 0.33: 1.

The absolute length L _{BX of} the suction path BX and the absolute length of the closed path L _{XD of} the closed path XD is - as long as the resulting ratio L _BX : L _XD in the range _{according to} the invention - within wide ranges adjustable. In order to obtain the above-described advantageous effects of the method according to the invention particularly pronounced, it is preferred that L _{BX has} a length in the range of 5 cm to 50 cm and L _{XD has} a length in the range of 20 cm to 150 cm. The process according to the invention is particularly preferably carried out with values of L _BX in the range from 10 cm to 25 cm and with values of L _XD in the range from 35 cm to 75 cm. The process according to the invention is most preferably carried out with values of L _BX in the range from 12 cm to 21 cm and with values of L _XD in the range from 49 cm to 58 cm.

According to the invention, the distance between A and B is parallel to the nozzle hole exit plane. For the imaginary distance AB the Anblasstrecke AC forms an angle α and the suction line BX an angle β, wherein the amounts of α and β may be the same or different. In a preferred embodiment of the method according to the invention, the Anblasstrecke AC to the imaginary distance AB at an angle α of 60 ° to 90 ° and the Absaugstrecke BX has the imaginary distance AB at an angle β of 60 ° to 90 °.

In a particularly preferred embodiment of the method according to the invention, the Anblasstrecke AC to the imaginary line AB at an angle α of 90 ° and the suction line BX has the imaginary distance AB at an angle β of 90 °.

In a further particularly preferred embodiment of the method according to the invention, the Anblasstrecke AC to the imaginary distance AB at an angle α of 60 ° to <90 ° and the suction line BX has the imaginary distance AB at an angle β of 90 °.

In principle, when carrying out the method according to the invention, it is possible for the angle β, which the evacuation path BX forms to the imaginary distance AB, to be different from the angle β 'which the distance XD forms to the imaginary distance AB. However, the method according to the invention is preferably carried out so that the angles β and β 'are the same.

In the method according to the invention, the filament bundle in the first cooling zone is transversely blown through the gaseous cooling medium and cooled by means of a suction opposite the Queranblasung suction through the distance BX. This can be done, for example, such that the filament bundle between the Anblasstrecke AC of length L and the suction line BX of length L _{BX is} passed. Another possibility is to divide the filament and, for example, set up in the middle between two filament streams in the first cooling zone An blowing line AC of length L, for example in the form of a perforated tube of length L. In this embodiment, then the gaseous cooling medium of blow the center of the filament bundles outward through the filament bundles via the blowing line AC of length L and suction through the suction section BX of length L _BX . Furthermore, the method according to the invention can also be carried out in such a way that a perforated tube extending in the middle of the filament _streams acts as a suction path BX of length L _BX and sucks the gaseous cooling medium, which is transversely blown across the Anblasstrecke AC of length L from outside to inside.

It is preferred for the method according to the invention if the flow velocity of the gaseous cooling medium in the first cooling zone is between 0.1 and 1 m / s. At these rates, there is a uniform cooling largely without turbulence and formation of skin / core differences in the crystallization.

In a further preferred embodiment of the method according to the invention, the gaseous cooling medium, before it is supplied to the at least one transverse blowing in the first cooling zone, is tempered by means of a first tempering device, i. cooled or heated. This embodiment allows process control independent of the ambient temperature, which is advantageous for the long-term stability of the method, e.g. regarding day-night or summer-winter differences.

The second stage of the cooling is carried out in the process according to the invention by means of self suction ("self suction yarn cooling"). At this time, the filament bundle ruptures the gaseous cooling medium in its vicinity, e.g. Ambient air, with it and is thereby cooled further. In this case, there is a flow of the gaseous cooling medium, which runs substantially parallel to the direction of the filament bundle. It is important that the gaseous cooling medium approaches the filament bundle at least from two sides.

This can be achieved in the method according to the invention in that the self-priming unit is formed by two perforated materials that run parallel to the filament bundle, such as perforated plates. The length of the plates is at least 10 cm and can be up to several meters at the top. Quite usual are lengths for this Selbstansaugungsstrecke of 30 cm to 150 cm, which are also suitable for the inventive method.

In the manner just described, a preferred embodiment of the method according to the invention can be carried out, wherein in the second cooling zone the filament bundle is thus positioned between perforated materials, e.g. perforated plates, it is carried out that the gaseous cooling medium can hit the filaments by self-suction of the filaments of the filament bundle from two sides.

In a further preferred embodiment of the method according to the invention, the filament bundle in the second cooling zone is passed through a perforated tube. Such "self-suction tubes" are known in the art. They allow entrainment of the gaseous cooling medium by the filament bundle in a manner which largely avoids turbulence. The perforated tube has a porosity P _tube = F _o / F in the range of 0.1 to 0.9 and particularly preferably in the range of 0.30 to 0.85, where F _o the open lateral surface of the tube and F the entire Lateral surface of the pipe means.

However, the second cooling zone may also be configured as a "self-suction zone" to form a well having a square or rectangular footprint, the walls of the well being formed from two opposed closed plates and two opposing porous plates. In this case, the one porous plate has a porosity P ₁ = F _o1 / F ₁ , where F _o1 the open area of this plate and F _{1 means} the entire surface of this plate. Further, the other porous plate has a porosity P ₂ = F _o2 / F ₂ , where F _{o2 is} the open area of this plate and F _{2 is} the entire area of this plate. The porosity of one plate P ₁ may be the same or different from the porosity P _{2 of} the other plate. The values of P ₁ and P ₂ are preferably in the range of 0.1 to 0.9, more preferably in the range of 0.2 to 0.85.

It is possible to temper the cooling medium, which is sucked through the filament bundle in the second cooling zone, for example by the use of heat exchangers. This embodiment allows one of the ambient temperature independent process management, which has an advantageous effect on the long-term stability of the process, eg with regard to day-night or summer-winter differences.

Between the spinneret or nozzle plate and the beginning of the first cooling zone is usually still a heating tube. Depending on the filament type, this element, which is familiar to the person skilled in the art, is between 10 and 40 cm long.

As already mentioned, the method according to the invention in the first cooling zone comprises at least one transverse blowing through a gaseous cooling medium. This means that the first cooling zone can not only have a first transverse blowing but also a second, third, etc. transverse blowing, these transverse blowing on the blowing line AC are arranged directly one after the other and have the length L in total. In principle, each of these Queranblasungen be operated with a Anblasmenge of gaseous cooling medium, which is independently adjustable by the Anblasmengen of gaseous cooling medium, with which the respective other Queranblasungen be operated. Furthermore, in principle, each of these Queranblasungen can be operated with a temperature of the gaseous cooling medium, which is independently adjustable from the temperatures of the gaseous cooling media, with which the respective other Queranblasungen operated.

In a preferred embodiment of the method the first transverse blowing with a stream velocity V _11, the first cooling zone on the blowing section AC, a first transverse blowing and an immediately adjoining second transverse blowing, whereby the first and second transverse blowing have a total length L, and wherein of the gaseous cooling medium is operated, and the second Queranblasung is operated with a flow velocity of the gaseous cooling medium V ₁₂ , and wherein V _{11 is} different from V _12th

In a further preferred embodiment of the method according to the invention, the first cooling zone on the Anblasstrecke AC a first Queranblasung and an immediately adjoining second Queranblasung, wherein the first and second Queranblasung in sum have the length L, and wherein the first Queranblasung is operated at a temperature T _{11 of} the gaseous cooling medium and the second Queranblasung is operated at a temperature T _{12 of} the gaseous cooling medium , and wherein T _{11 is} different from T ₁₂ .

By the o.g. In both embodiments, it is possible to adapt the cooling conditions in the first cooling zone particularly precisely to changing cooling requirements.

The inventive method can also be carried out so that the filament bundle is further cooled in the second cooling zone by Selbstansaugung located in the vicinity of the filament bundle gaseous cooling medium, wherein the gaseous cooling medium is heated prior to entry into the second cooling zone.

In the process according to the invention, a gaseous cooling medium is used to cool the filament bundle. For the purposes of the present invention, this means any gaseous medium which is suitable for cooling filament bundles without undesirably influencing the properties of the resulting multifilament yarn, e.g. by forming undesirable reaction products from the gaseous cooling medium and the resulting multifilament yarn. In the process according to the invention, preference is given to using air and / or an inert gas, such as nitrogen or argon, as the gaseous cooling medium, it being possible to use either the same or different gaseous cooling media in the first and second cooling zones.

In a preferred embodiment of the method according to the invention takes place after cooling of the filament bundle in the second cooling zone and before winding a single or multi-stage drawing of the filaments. Thus, the process of the invention is preferably a continuous spin-draw take-up - Method ("spinning drawing winding process"). The term stretching is to be understood here as meaning all customary methods familiar to the person skilled in the art in order to distort the filaments. This can be done for example by godets, individually or in duos, or the like. It should be expressly mentioned that drawing refers both to draw ratios greater than 1 and to ratios which are less than 1. The latter ratios are familiar to those skilled in the art of relaxation. In the process according to the invention, draw ratios greater than and less than 1 can occur quite side by side.

The total draw ratio is usually calculated from the ratio of the draw speed to the filament spin speed, i. the speed at which the filament bundles leave the cooling zones and are fixed to the first godet pair of the drawing device. A typical constellation is, for example, a spinning speed of 2760 m / min, a stretching speed of 6000 m / min, an additional relaxation following the stretching of 0.5%, i. a speed of the last godet of 5970 m / min. This results in a total draw ratio of 2.17.

Therefore, according to the invention, speeds of at least 2000 m / min are preferred for winding, in particular of at least 2500 m / min. In principle, there are no limits to the speed of the process within the framework of the technically feasible. Generally, however, about 8000 m / min, more preferably 6500 m / min, is preferred for the upper speed range during winding. At the usual total draw ratios of 1.5 to 3.0, therefore, ranges of about 500 to about 4000 m / min, preferably 2000 to 3500 m / min and more preferably from 2500 to 3500 m / min for the spinning speed.

The drafting devices upstream and behind the cooling zones can still be a known chute.

The inventive method is in principle suitable for spinning a multifilament yarn of any thermoplastic material and is therefore not limited to certain thermoplastic materials. On the contrary, the method according to the invention can be used for spinning all filament extrudable thermoplastic materials, in particular for spinning a multifilament yarn made of a thermoplastic polymer. Therefore, the thermoplastic material to be used in the process according to the invention is preferably selected from a group comprising thermoplastic polymers, which group may contain polyester, polyamide, polyolefin or mixtures or copolymers of these polymers.

Most preferably, the thermoplastic material used in the process according to the invention consists essentially of polyethylene terephthalate.

• Aus einer Spinndüse 1 wird durch eine Vielzahl von Düsenlöchern, deren Enden eine Düsenlochaustrittsebene bilden, ein multifiler Faden, d.h. ein Filamentbündel 2 gesponnen. Das Filamentbündel 2 wird mit einer Vorrichtung zur Queranblasung I mit gasförmigem Kühlmedium angeblasen. Die Queranblasung erfolgt über eine Anblasstrecke AC der Länge L, wobei A den oberen den Düsenlöchern zugewandten Anfang und C das untere von den Düsenlöchern abgewandte Ende der Anblasstrecke AC bildet. Die Punkte A bzw. C bezeichnen das obere bzw. untere Ende der ersten Abkühlzone. Gegenüber der Anblasstrecke AC ist eine Strecke BD angeordnet, welche einen den Düsenlöchern zugewandten Anfang B und ein von den Düsenlöchern abgewandtes Ende D aufweist. A und B sind so angeordnet, dass die zwischen A und B gedachte Strecke AB parallel zur Düsenlochaustrittsebene verläuft.

Fig. 1 shows a schematic cross section of an exemplary apparatus for carrying out the method according to the invention:

• From a spinneret 1, a multifilament yarn, that is, a filament bundle 2 is spun by a plurality of nozzle holes whose ends form a die hole exit plane. The filament bundle 2 is blown with a device for Queranblasung I with gaseous cooling medium. The Queranblasung takes place via a Anblasstrecke AC of length L, wherein A the upper nozzle holes facing the beginning and C forms the lower end of the Anblasstrecke AC facing away from the nozzle holes. The points A and C respectively denote the upper and lower ends of the first cooling zone. Opposite the Anblasstrecke AC a distance BD is arranged, which has a nozzle holes facing the beginning of B and facing away from the nozzle holes end D. A and B are arranged so that the distance AB between A and B is parallel to the nozzle hole exit plane.

The angle α between the imaginary distance AB and the Anblasstrecke AC is 90 °. The angle β between the imaginary distance AB and the distance BD is also 90 °. The distance BD is subdivided into an open suction section BX of length L _BX , via which the gaseous cooling medium is sucked off with a suction device II, and into a closed section XD of length L _XD , wherein the ratio L _BX : L _{XD is} in the range of 0 , 15: 1 to 0.5: 1.

Below the first cooling zone, whose left end is denoted by C and whose right end is denoted by D, immediately followed by a second cooling zone. Thus, C and D also mark the beginning of the left and right sides of the second cooling zone. The second cooling zone is defined on the left by a perforated plate which forms a self-priming path CE of length L _CE , via which the filament bundle 2 sucks gaseous cooling medium solely by its movement. The second cooling zone is defined on the right by another perforated plate, which forms a self-priming path DF of length L _DF , via which the filament bundle 2 also sucks gaseous cooling medium solely by its movement. The subsequent stretching and winding of the spun multifilament to the second cooling zone is not shown.

As mentioned above, the process according to the invention allows for the first time the production of a multifilament yarn, in particular a polyester multifilament yarn in a continuous spin-draw winding process with a total titer of at least 1800 dtex, a dimensional stability Ds = EAST + HAS of at most 11.0% and with a number of lint which is at least 5% less than the lint number of a polyester filament yarn spun under the same conditions, except that L _BX : L _XD = 1.

Therefore, such a polyester multifilament yarn is also part of the present invention. In this case, the upper limit of the total titre can in principle assume arbitrarily large values, as explained in the following: The jet hole exit plane mentioned at the outset can be embodied as part of a spinneret plate which has a Has length and a width. By extending the spinneret plate in the width, it is in principle possible to spider arbitrarily large total titers by means of the method according to the invention. However, for practical reasons, those skilled in the art will choose an upper limit on the total denier of the polyester multifilament yarn which is in the range of 1800 dtex to 5000 dtex, and preferably in the range of 2000 dtex to 3600 dtex.

In a preferred embodiment, the polyester multifilament yarn has a dimensional stability Ds = EAST + HAS of at most 10.5%.

In a further preferred embodiment, the polyester multifilament yarn has a breaking strength of more than 60 cN / tex, particularly preferably more than 65 cN / tex.

In a further preferred embodiment, the polyester multifilament yarn has a lint count that is at least 50%, more preferably at least 60% less than the lint number of a polyester filament yarn spun under the same conditions except that L _BX : L _XD = 1. For example, the number of lint is less than 500 per 10 kg of yarn, more preferably less than 250 per 10 kg of yarn.

In a further preferred embodiment, the polyester multifilament yarn has a yarn breakage rate of less than 25 per 1000 kg of yarn, more preferably less than 10 per 1000 kg of yarn.

The polyester multifilament yarn according to the invention is preferably characterized in that the yarn has a breaking strength T in mN / tex and an elongation at break E in%, the product consisting of the breaking strength T and the third root of the breaking elongation E, T • E1 ^1/3 , at least 1600 mN% ^1/3 / tex and preferably between 1600 and 1800 mN% ^1/3 / tex.

The measurements of the breaking strength T and the elongation at break E for the determination of the parameter T • E ^1/3 are carried out in accordance with ASTM 885 and are otherwise known to the person skilled in the art.

The number of lint per 10 kg of yarn is determined with the ENKA Tecnica FR V.

The determination of the thread breaks per 1000 kg of yarn is done by counting.

The EAST is measured according to ASTM 885 and the HAS is also determined according to ASTM 885, with the proviso that the measurement is carried out at 180 ° C, at 5 mN / tex and over a measurement period of 2 minutes.

The o.g. Polyester multifilament yarn is particularly well suited for technical applications, especially for use in tire cord.

An undoped cord made of the polyester multifilament yarn of the present invention has a value of T • E ^1/3 which is at least 1375 mN% ^1/3 / tex, preferably up to 1800 mN% ^1/3 / tex. Therefore, such an undipped cord is also part of the present invention.

Finally, the present invention includes a dipped cord comprising a polyester multifilament yarn produced by the process according to the invention, the cord having a retention capacity Rt after dipping and characterized by the quality factor Q _f , ie the product of T • E ^{1/3 of} the polyester multifilament yarn and Rt of the cord, is greater than 1350 mN% ^1/3 / tex and preferably up to 1800 mN% ^1/3 / tex.

The retention capacity is the dimensionless quotient of the breaking strength of the cord after dipping and the breaking strength of the threads.

Furthermore, the method is also well suited for the production of technical yarns. The settings necessary for the spinning of technical yarns, in particular the choice of the nozzle and the length of the heating tube, are known to the person skilled in the art.

The invention will be explained in more detail with reference to the following examples, without being limited to these examples.

Example 1: Preparation of polyethlene terephthalate multifilament yarns having a yarn count of 2220 dtex

Polyethylene terephthalate granules having a relative viscosity of 2.04 (measured on a solution of 1 g of polymer in 125 g of a mixture of 2,4,6-trichlorophenol and phenol (TCF / F, 7:10 m / m) at 25 ° C in an Ubbelohde (DIN 51562) viscometer) is spun, where α = β = 90 ° is selected, and cooled. The spun filament bundle first passes through a heating tube, then through the first cooling zone directly adjoining the heating tube and through the second cooling zone directly adjoining the first cooling zone.

In this case, the first cooling zone on a Anblasstrecke, which is divided into a first Queranblasung and immediately thereafter in a second Queranblasung, by means of which the filament bundle is transversely blown with air of different temperature and flow velocity. The first Queranblasung opposite and immediately after the heating tube is an open suction of certain length, through which the cross-blown air is sucked off with a certain suction. Immediately after the suction line follows a closed route of certain length.

Immediately following the second transverse blowing of the first cooling zone, the second cooling zone follows, which is formed by a shaft comprising two opposing porous plates with different porosity, one plate below the Anblasstracke the first cooling zone and the second plate below the suction of the first cooling zone is arranged. In the second cooling zone, the filament bundle is cooled by the air which it sucks as a result of its movement through the porous plates. Table 1 summarizes the spinning and cooling conditions. Where: L Length of the blowing line in the first cooling zone T ₁₁ Temperature of the air at which the filament bundle is transversely blown in the first transverse blowing of the first cooling zone; v ₁₁ Flow velocity of the air with which the filament bundle is transversely blown in the first transverse blowing of the first cooling zone; L ₁₁ Length of the first transverse blowing in the first cooling zone; T ₁₂ Temperature of the air at which the filament bundle is transversely blown in the second transverse blowing of the first cooling zone; v ₁₂ Inflow velocity of the air with which the filament bundle is transversely blown in the second transverse blowing of the first cooling zone; L ₁₂ Length of the second transverse blowing in the first cooling zone; L _BX Length of the open suction line BX in the first cooling zone; L _XD Length of the closed path XD in the first cooling zone; V / t Suction power with which the air in the first cooling zone is sucked through the open suction section BX of length L _BX ; P ₁ Porosity of the porous plate in the second cooling zone below the Anblasstrecke; P ₂ Porosity of the porous plate in the second cooling zone below the suction section; T ₂ Temperature of the self-sucked by the filament bundle in the second cooling zone air; L _CE Length of the self-priming section in the second cooling zone; <b> Table 1: </ b> spinning and cooling conditions yarn count 2200 [Dtex] individual titre 4.4 [Dtex] spinneret - number of holes 501 - hole diameter 800 [.Mu.m] Length of the heating tube 150 [Mm] Temperature in the heating tube 200 [° C] First cooling zone - L 700 [Mm] - T ₁₁ 55 [° C] - V ₁₁ 0.60 [M / min] - L ₁₁ 500 [Mm] - T ₁₂ 30 [° C] - V ₁₂ 0.85 [M / min] - L ₁₂ 200 [Mm] - V / t 230 [m ³ / h] - L _BX 160 [Mm] - L _XD 540 [Mm] - L _BX : L _XD 0.30 Second cooling zone - L _CE 500 [Mm] - T ₂ 30 [° C] - P ₁ 0.32 - P ₂ 0.70

Immediately after passing through the second cooling zone, the multifilament is bundled and passed through a tube in a drawing device, whereby the multifilament is stretched and wound with the draw ratios shown in Table 2 at a drawing speed of 6000 m / min, whereby one-piece produced polyethlene terephthalate multifilament with a Yarn titer of 2200 dtex, whose lint and breaking strengths, T • E ^1/3 values and dimensional stabilities Ds are also listed in Table 2 (see yarns Nos. 1-8).

Comparative Example 1

For comparison, the polyethylene terephthalate multifilament yarns No. V1-V6 are prepared as in Example 1 with the difference that in the first cooling zone, the suction takes place over the entire length BD = L = 700 mm. <b> Table 2: Draw ratios, draw speeds V <s>, break strengths T, T • E <sup> 1/3 </ sup> values, flow numbers and Ds of the polyethylene terephthalate of the present invention Multi-filament yarns Nos. 1-8 and comparative polyethylene terephthalate multifilament yarns Nos. V1-V6 example 1 Yarn no. 1 2 3 4 5 6 7 8th draw ratio 2,000 2.025 2,050 2,075 2,100 2,125 2,150 2,175 V _s [m / min] 6000 6000 6000 6000 6000 6000 6000 6000 T [mN / tex] 607 633 621 635 647 667 670 689 T • E ^1/3 [mN% ^1/3 / tex] 1560 1588 1529 1564 1584 1617 1597 1628 fluff 160 129 244 157 132 212 257 417 Ds [%] 11.0 10.6 10.9 11.0 11.0 10.9 11.0 10.9 Comparative Example 1 Yarn no. V1 V2 V3 V4 V5 V6 - - draw ratio 2,000 2.025 2,050 2,075 2,100 2,125 - - v _s [m / min] 6000 6000 6000 6000 6000 6000 - - T [mN / tex] 617 633 622 663 656 651 - - T • E ^1/3 [mN% ^1/3 / tex] 1561 1569 1529 1621 1568 1570 - - fluff 172 405 687 876 977 1265 - - Ds [%] 11.0 11.2 11.3 11.1 11.1 11.4 - -

The comparison of the lint numbers of the yarns 1-6 produced according to the invention with the lint numbers of the comparative yarns V1-V6 shows that the process according to the invention leads to yarns having a significantly smaller number of lintens and thus to a considerable amount improved running behavior of the multifilament leads. The reduction of the number of lint in this example is between 7% (compare yarn 1 with comparative yarn V1) and 86% (compare yarn 5 with comparison yarn V5). The dimensional stability Ds of the yarns produced according to the invention is at most 11.0% and, under otherwise identical conditions, is equal to or even better than Ds of comparative yarns V1-V6. Furthermore, the yarns 7 and 8 produced according to the invention show that it is possible with the process according to the invention to produce yarns having a yarn denier of 2200 dtex, high strength and a number of lint, which permits continuous spinning. In contrast, the attempt to set a draw ratio of 2.150 under the conditions of the comparative example at a stretching speed of 6000 m / min leads to such an intensive bonding of the filaments that continuous spinning is impossible. This applies first of all to the attempt to set a stretch ratio of 2.175 under the conditions mentioned. Finally, the yarns 6 and 8 produced according to the invention show that the process according to the invention makes it possible, when a suitable draw ratio is selected, to bring the T • E ^1/3 values into the preferred range of at least 1600 mN% ^1/3 / tex.

Example 2: Preparation of polyethlene terephthalate multifilament yarns having a yarn denier of 1670 dtex

Polyethylene terephthalate granules having a relative viscosity of 2.04 (measured on a solution of 1 g of polymer in 125 g of a mixture of 2,4,6-trichlorophenol and phenol (TCF / F, 7:10 m / m) at 25 ° C in an Ubbelohde (DIN 51562) viscometer) was spun, with α = β = 90 °. The spun filament bundles pass through a heating tube as in Example 1, then through the immediately following first cooling zone and through the immediately following second cooling zone. Table 3 summarizes the spinning and cooling conditions, the spinning and cooling parameters having the same meaning as in Example 1. <b> Table 3: </ b> spinning and cooling conditions yarn count 1670 [Dtex] individual titre 4.1 [Dtex] spinneret - number of holes 412 - hole diameter 800 [.Mu.m] Length of the heating tube 150 [Mm] Temperature in the heating tube 200 [° C] First cooling zone - L 700 [Mm] - T ₁₁ 55 [° C] - v ₁₁ 0.60 [M / min] - L ₁₁ 500 [Mm] - T ₁₂ 55 [° C] - v ₁₂ 0.85 [M / min] - L ₁₂ 200 [Mm] - V / t 230 [m ³ / h] - L _BX 160 [Mm] - L _XD 540 [Mm] - L _BX : L _XD 0.30 Second cooling zone - L _CE 500 [Mm] - T ₂ 30 [° C] - P ₁ 0.23 - P ₂ 0.32

Immediately after passing through the second cooling zone, the multifilament is bundled and passed through a tube in a drawing device, whereby the multifilament is stretched and wound with the draw ratios shown in Table 4 at a drawing speed of 6000 m / min, whereby one-piece produced Polyethlenterephthalat-Multifilamentgarne with a Yarn titer of 1670 dtex, whose lint and breaking strengths, T • E ^1/3 values and dimensional stabilities Ds are also listed in Table 4 (see yarns Nos. 1-9).

Comparative Example 2:

For comparison, the polyethylene terephthalate multifilament yarns No. V1-V9 were prepared as in Example 2, except that in the first cooling zone, the suction was performed over the entire length BD = L = 700 mm. <b> Table 4: Draw ratios, draw speeds V <s>, break strengths T, T • E <sup> 1/3 </ sup> values, flow numbers and Ds of the polyethylene terephthalate of the present invention Multi-filament yarns Nos. 1-9 and comparative polyethylene terephthalate multifilament yarns Nos. V1-V9 Example 2 Yarn no. 1 2 3 4 5 6 7 8th 9 draw ratio 2,000 2.025 2,050 2,075 2,100 2,125 2,150 2,175 2,200 v _s [m / min] 6000 6000 6000 6000 6000 6000 6000 6000 6000 T [mN / tex] 622 646 666 645 680 702 694 699 740 T • E ^1/3 [mN% ^1/3 / tex] 1595 1623 1627 1603 1659 1649 1620 1617 1698 fluff 20 31 23 22 30 26 50 90 110 Ds [%] 10.4 10.3 10.3 10.8 10.6 10.4 10.6 10.6 10.5 Comparative Example 2 Yarn no. V1 V2 V3 V4 V5 V6 V7 V8 V9 draw ratio 2,000 2.025 2,050 2,075 2,100 2,125 2,150 2,175 2,200 v _s [m / min] 6000 6000 6000 6000 6000 6000 6000 6000 6000 T [mN / tex] 620 628 640 657 635 667 677 681 687 T • E ^1/3 [mN% ^1/3 / tex] 1597 1582 1591 1630 1535 1608 1620 1607 1568 fluff 41 32 18 32 41 48 174 877 363 Ds [%] 10.6 10.5 10.5 10.4 10.9 10.8 10.9 10.9 10.9

The comparison of the lint numbers of the yarns 1-9 produced according to the invention with the lint numbers of the comparison yarns V1-V9 shows that the process according to the invention almost always leads to yarns having a significantly smaller number of lintens and thus to a considerably improved running behavior of the multifilament. The dimensional stability Ds under otherwise identical conditions is almost always better than Ds of comparative yarns V1-V9.

Example 3: Preparation of polyethlene terephthalate multifilament yarns having a denier of 1440 dtex

Polyethylene terephthalate granules having a relative viscosity of 2.04 (measured on a solution of 1 g of polymer in 125 g of a mixture of 2,4,6-trichlorophenol and phenol (TCF / F, 7:10 m / m) at 25 ° C in an Ubbelohde (DIN 51562) viscometer) was spun using α = β = 90 ° and cooled. The spun filament bundles pass through a heating tube as in Example 1, then through the immediately following first cooling zone and through the immediately following second cooling zone. Table 5 summarizes the spinning and cooling conditions, the spinning and cooling parameters having the same meaning as in Example 1. <b> Table 5: </ b> spinning and cooling conditions yarn count 1440 [Dtex] individual titre 4.4 [Dtex] spinneret - number of holes 331 - hole diameter 800 [.Mu.m] Length of the heating tube 150 [Mm] Temperature in the heating tube 200 [° C] First cooling zone. - L 700 [Mm] - T ₁₁ 55 [° C] - v ₁₁ 0.60 [M / min] - L ₁₁ 500 [Mm] - T ₁₂ 55 [° C] - v ₁₂ 0.85 [M / min] - L ₁₂ 200 [Mm] - V / t 230 [m ³ / h] - L _BX 160 [Mm] - L _XD 540 [Mm] - L _BX : L _XD 0.30 Second cooling zone - L _CE 500 [Mm] - T ₂ 30 [° C] - P ₁ 0.23 - P ₂ 0.32

Immediately after passing through the second cooling zone, the multifilament is bundled and passed through a tube in a drawing device, whereby the multifilament is stretched and wound with the draw ratios shown in Table 6 at a drawing speed of 6000 m / min, whereby one-piece produced polyethlenterephthalate multifilament with a Yarn titer of 1440 dtex, whose lint and breaking strengths, T • E ^1/3 values and dimensional stabilities Ds are also listed in Table 6 (see yarns Nos. 1-9).

Comparative Example 3

For comparison, the polyethylene terephthalate multifilament yarns No. V1-V9 are prepared as in Example 3, except that in the first cooling zone, the suction was performed over the entire length BD = L = 700 mm. <b> Table 6: </ b> stretch ratios, draw speeds v <s>, breaking strengths T, T • E <sup> 1/3 </ sup> values, flow numbers and Ds of the polyethylene terephthalate of the present invention Multi-filament yarns Nos. 1-9 and comparative polyethylene terephthalate multifilament yarns Nos. V1-V9 Example 3 Yarn no. 1 2 3 4 5 6 7 8th 9 draw ratio 2,000 2.025 2,050 2,075 2,100 2,125 2,150 2,175 2,200 v _s [m / min] 6000 6000 6000 6000 6000 6000 6000 6000 6000 T [mN / tex] 631 606 643 660 679 668 684 703 729 T • E ^1/3 [mN% ^1/3 / tex] 1642 1537 1633 1643 1695 1661 1633 1685 1672 fluff 6 10 55 18 10 15 26 17 49 Ds [%] 10.8 11.1 11.0 10.9 10.8 11.0 10.9 11.0 10.8 Comparative Example 3 Yarn no. V1 V2 V3 V4 V5 V6 V7 V8 V9 draw ratio 2,000 2.025 2,050 2,075 2,100 2,125 2,150 2,175 2,200 v _s [m / min] 6000 6000 6000 6000 6000 6000 6000 6000 6000 T [mN / tex] 635 645 659 662 666 670 691 699 701 T • E ^1/3 [mN% ^1/3 / tex] 1620 1578 1659 1868 1629 1622 1654 1688 1674 fluff 15 14 53 41 67 32 78 315 212 Ds [%] 10.7 10.7 10.6 11.0 10.8 11.1 11.1 10.9 10.8

The comparison of the lint numbers of the yarns 1-9 produced according to the invention with the lint numbers of the comparison yarns V1-V9 shows that the process according to the invention almost always leads to yarns having a significantly smaller number of lintens and thus to a considerably improved running behavior of the multifilament.

Claims (29)

1. Method for spinning a multifilament yarn from a thermoplastic material, comprising the steps of extruding the melted material through a spinneret to form a filament bundle with a plurality of filaments and winding the filaments as multifilament yarn after solidifying, wherein the spinneret has a plurality of spinneret holes and the ends of the holes at which the filaments discharge form a spinneret hole discharge plane, and wherein the filament bundle following the spinneret is cooled in a first cooling zone initially by at least one instance of transversely blowing a gaseous cooling medium and by extracting the gaseous cooling medium opposite said transverse blowing instance, and then, in a second cooling zone beneath the first cooling zone, the filament bundle is cooled further by self-suction of gaseous cooling medium located in the vicinity of the filament bundle, characterized in that in the first cooling zone the at least one transverse blowing instance for the gaseous cooling medium extends over a blowing section AC of length L, wherein the blowing section AC has an upper start A facing the spinneret holes and a lower end C facing away from the spinneret holes, and arranged opposite the blowing section AC is a section BD, which has a start B facing the spinneret holes and an end D facing away from the spinneret holes, and the imaginary section AB runs between A and B parallel to the spinneret hole discharge plane, wherein the section BD has the length L, and wherein the section BD is subdivided into an open extraction section BX of length L_BX, via which the gaseous cooling medium is extracted, and a closed section XD of length L_XD, wherein the ratio L_BX:L_XD lies in the range from 0.15:1 to 0.5:1.
2. Method according to Claim 1, characterized in that the ratio L_BX:L_XD lies in the range from 0.2:1 to 0.4:1.
3. Method according to Claim 1 or 2, characterized in that L_BX has a length in the range from 5 cm to 50 cm and L_XD has a length in the range from 20 cm to 150 cm.
4. Method according to one or more of Claims 1 to 3, characterized in that the blowing section AC has an angle α of 60° to 90° to the imaginary section AB and the extraction section BX has an angle β of 60° to 90° to the imaginary section AB.
5. Method according to Claim 4, characterized in that the blowing section AC has an angle α of 90° to the imaginary section AB and the extraction section BX has an angle β of 90° to the imaginary section AB.
6. Method according to Claim 4, characterized in that the blowing section AC has an angle α of 60° to < 90° to the imaginary section AB and the extraction section BX has an angle β of 90° to the imaginary section AB.
7. Method according to one or more of Claims 1 to 6, characterized in that the gaseous cooling medium transversely blown in the first cooling zone has a flow velocity between 0.1 and 1 m/s.
8. Method according to one or more of Claims 1 to 7, characterized in that the gaseous cooling medium is conditioned by means of a first temperature control device before it is fed in the first cooling zone to the at least one transverse blowing instance.
9. Method according to one or more of Claims 1 to 8, characterized in that in the second cooling zone the filament bundle is fed between perforated materials, e.g. perforated plates, in such a way that the gaseous cooling medium can reach the filaments from two sides due to self-suction of the filaments of the filament bundle.
10. Method according to one or more of Claims 1 to 8, characterized in that in the second cooling zone the filament bundle is fed through a perforated tube.
11. Method according to one or more of Claims 1 to 10, characterized in that the first cooling zone along the blowing section AC has a first transverse blowing instance and a second transverse blowing instance directly subsequent thereto, wherein the first and second transverse blowing instances have the length L in sum, and wherein the first transverse blowing instance is operated at a velocity v₁₁ of the gaseous cooling medium and the second transverse blowing instance is operated at a velocity v₁₂ of the gaseous cooling medium, where v₁₁ is different from v₁₂.
12. Method according to one or more of Claims 1 to 11, characterized in that the first cooling zone along the blowing section AC has a first transverse blowing instance and a second transverse blowing instance directly subsequent thereto, wherein the first and second transverse blowing instances have the length L in sum, and wherein the first transverse blowing instance is operated at a temperature T₁₁ of the gaseous cooling medium and the second transverse blowing instance is operated at a temperature T₁₂ of the gaseous cooling medium, where T₁₁ is different from T₁₂.
13. Method according to one or more of Claims 1 to 12, characterized in that the filament bundle is further cooled in the second cooling zone by self-suction of gaseous cooling medium located in the vicinity of the filament bundle, wherein the gaseous cooling medium is temperature-conditioned prior to entry into the second cooling zone.
14. Method according to one or more of Claims 1 to 13, characterized in that air and/or an inert gas is used as the gaseous cooling medium.
15. Method according to one or more of Claims 1 to 14, characterized in that the filaments are drawn in one or more steps after the cooling of the filament bundle in the second cooling zone and before winding.
16. Method according to one or more of Claims 1 to 15, characterized in that the winding is performed at speeds of at least 2500 m/min.
17. Method according to one or more of Claims 1 to 16, characterized in that the thermoplastic material is selected from a group that comprises thermoplastic polymers, wherein the group contains polyester, polyamide, polyolefin or mixtures and/or copolymers of these polymers.
18. Method according to one or more of Claims 1 to 17, characterized in that the thermoplastic material consists substantially of polyethylene terephthalate.
19. Polyester multifilament yarn obtained by a method according to one or more of Claims 1 to 18 with a dimensional stability of at most 11.0% and with a fluff index which is at least 5% lower than the fluff index of a polyester filament yarn that is spun under the same conditions except that L_BX = L.
20. Polyester multifilament yarn according to Claim 19 with a dimensional stability of at most 10.5%.
21. Polyester multifilament yarn according to Claim 19 or 20 with a breaking tenacity of more than 60 cN/tex.
22. Polyester multifilament yarn according to Claim 21 with a breaking tenacity of more than 65 cN/tex.
23. Polyester multifilament yarn according to one or more of Claims 19 to 22 with a fluff index which is at least 50% lower than the fluff index of a polyester filament yarn that is spun under the same conditions except that L_BX = L.
24. Polyester multifilament yarn according to Claim 23 with a fluff index which is at least 60% lower than the fluff index of a polyester filament yarn that is spun under the same conditions except that L_BX = L.
25. Polyester multifilament yarn according to one or more of Claims 19 to 24 with a filament breakage rate of less than 25 per 1000 kg of yarn.
26. Polyester multifilament yarn according to Claim 25 with a filament breakage rate of less than 10 per 1000 kg of yarn.
27. Polyester multifilament yarn according to one of more of Claims 19 to 26, characterized in that the yarn has a breaking tenacity T in mN/tex and an elongation at rupture E in %, wherein the product of the breaking tenacity T and the cube root of the elongation at rupture E, T•E^1/3, is at least 1600 mN %^1/3/tex.
28. Undipped cord comprising a polyester multifilament yarn according to Claim 27, characterized in that the cord has a value of at least 1375 mN %^1/3/tex for the product T•E^1/3.
29. Dipped cord comprising a polyester multifilament yarn according to Claim 27, wherein the cord has a retention capacity Rt, characterized in that the quality factor Q_f, i.e. the product of T•E^1/3 of the polyester filament yarns and Rt of the cord, is greater than 1350 mN %^1/3/tex.

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