WO2003069034A1

WO2003069034A1 - A process for the production and for the winding of polyester multi-filament yarns as well as the polyester multi-filament yarns obtainable by said method and a device for the winding of one or more multi-filament yarns

Info

Publication number: WO2003069034A1
Application number: PCT/EP2003/001102
Authority: WO
Inventors: Ulrich Mirwaldt; Eckhard Seidel; Dietmar Wandel
Original assignee: Zimmer Ag
Priority date: 2002-02-12
Filing date: 2003-02-05
Publication date: 2003-08-21
Also published as: AU2003210208A1; CN1630741A; CN1316080C; DE10392272T5; JP2005517821A; KR20040094688A

Abstract

The present invention refers to a process for the production and for the winding of at least one polyester multi-filament yarn which consists of at least 90 weight %, in relation to the total weight of the polyester multi-filament yarn, of polybutylene terephthalate (PBT) and/or polytrimethylene terephthalate (PTMT), preferably of PTMT, to provide at least one yarn package with long-term stability during storage and which is insensitive against elevated temperatures during storage and transport wherein the wound package of said at least one polyester multi-filament yarn is heat-treated at a temperature in the range of > 45 °C to 65 °C. In addition the present invention relates to said polyester multi-filament yarn obtainable by said process wherein its elongation at break is in the range of > 60 to 145 % and its boil-off shrinkage is in the range of 0 to 10 %. Finally the present invention also claims a device (2) for the winding of one or more multi-filament yarns (26) comprising a casing (4) and a rotatable spindle on which a tube (30) may be fastened, so that the tube (30) is placed in said casing (4), wherein the interior of said casing (4) is heatable.

Description

A process for the production and for the winding of polyester multi-filament yarns as well as the polyester multi-filament yarns obtainable by said method and a device for the winding of one or more multi-filament yarns

Technical field:

The present invention relates to a process for the spinning and winding of polyester multi-filament yarns, which consist, in the amount of at least 90 weight %, in relation to the total weight of the polyester filament, of polybutylene terephthalate (PBT) and/or polytrimethylene terephthalate (PTMT), preferably of PTMT, as well as the polyester multi-filament yarns which can be obtained by means of the process and a device for the winding of one or more multi-filament yarns.

Background Art:

The production of continuous polyester multi-filament yarns, particularly polyethylene terephthalate (PET) multi-filament yarns, in a two-stage process, is already known. In this, multi-filament yarns are spun and wound during the first stage, which multi-filament yarns are, during a second stage, stretched into finished form and thermofixed, or else stretch-textured into bulky multi-filament yarns. Between the two stages, the packages of the multi-filament yarns can be long-term stored and transportet at elevated temperatures without any influence on the process conditions of the second texturing stage and the quality of the products.

The textbook "Synthetic Filaments" by F. Fourne (1995), published by Hanser- Verlag, Munich in German, provides a general overview of this field by describing the main principles underlying the spinning and winding technology. However, in contrast to PET multi-filament yarns, polytrimethylene terephthalate (PTMT) or polybutylene terephthalate (PBT) multi-filament yarns have a considerable shrinking tendency, both immediately after the spinning and upon the winding, as well as several hours or days after the winding, said tendency leading to a shortening of the multi-filament yarns. The yam package is thereby compressed so that, in an extreme case, the yam package can no longer be taken off the chuck. During long-term storage or transport especially at elevated temperatures the yarn package does not maintain its desired cheese-like shape and forms bulges with hard edges causing not only severe unwinding problems but also leading to a worsening of the yarn characteristics, such as extreme increase of uster values. Only the limitation of the weight of the yarn packages to less than 2 kg provides a remedy for these problems which normally do not occur during the processing of PET yarns.

Furthermore, it has been observed that, in contrast to PET multi-filament yarns, PBT multi-filament yarns or PTMT multi-filament yams age to an increased degree during storage. A stractural hardening appears, changing the characteristics of the multi-filament yarns (for example boil-off shrinkage, degree of crystallisation) with time. Nevertheless industrial use requires multi-filament yams maintaining their characteristics with time so that a subsequent processing of said multi-filament yams can be carried out continuously and provides multi- filament yarns with constant characteristics.

The differences in characteristics between PET and PBT or PTMT mentioned above are commonly attributed to their structural differences and are, for example, dealt with in Chemical Filaments Int., page 53, volume 50 (2000) and were one topic of the 39th Int. Man-Made Filaments Congress, September 13 to 15, 2001, in Dombirn. Thus, it is assumed that the differences in the chain formations, in the glass transition temperatures and in the elastic recovery behavior of these polymers are responsible for the differences in the yam characteristics.

First attempts to solve these problems are described in the international patent applications WO 99/27168 and WO 01/04393 and the European patent EP 0 731 196 Bl. The production of the polyester multi-filament yams which consists of at least 90 weight % of polytrimethylene terephthalate described in WO 99/27168 is carried out by means of spinning and stretching wherein the spinning speeds of 2100 m/min and lower are stated, which are too low from an economic point of view. The polyester multi-filament yams obtainable by this process exhibit a boil- off shrinkage of between 5% and 16% and an elongation at break of 20 % to 60 %, which is merely partly satisfying since due to the low elongation at break a higher number of processing defects has to be expected in the subsequent processing of these multi-filament yarns. In addition the final yarns will exhibit an insufficient low elongation at break.

WO 01/04393 refers to a process wherein the multi-filament yarns are heat-treated by the use of heated godets. Neither the stability in storage nor the stability during transport of the yam packages obtainable by said method are disclosed in WO 01/04393. A disadvantage of the process of WO 01/04393 consists in that it requires low spinning speeds to be effective. An increase of the spinning speed for economical reasons will decrease the contact time of the multi-filament yams at the heated godets and therefore result in a decreased long-term stability of the yarn packages.

The European patent EP 0 731 196 Bl claims a process for the spinning, stretching, and winding of a synthetic yam, wherein the yam, after the stretching step but before the winding step, is subjected to a heat treatment for the reduction of the shrinking tendency. Said heat-treatment is carried out by guiding the thread in close proximity but essentially without contact along an longitudinally extended heating surface, wherein the surface temperature of the heating surface is higher than the melting temperature of the thread. Usable synthetic yams also include polytrimethylene terephthalate yams. A treatment of the yarn package is not described in that document. Besides neither the stability in storage nor the stability during transport of the yarn packages is stated. Another problem commonly observed during the spinning and winding of multi- filament yarns is the noise nuisance, especially in the proximity of the winder. It has tlierefore been proposed to encage the winding device in a noise isolating box. However a heat-treatment of the yam package inside this acoustic-isolating box has not been disclosed in the prior art.

Disclosure of the invention:

It is an object of the present invention to overcome the problems of the prior art mentioned above. In particular it is an object of the present invention to provide a process for the spinning and winding of polyester multi-filament yarns which consist, by at least 90 weight % in relation to the total weight of the filaments, of PBT and/or PTMT, which allows the production and the winding of polyester multi-filament yarns in a simple way and manner. In particular, the polyester multi-filament yarns should exhibit a boil-off shrinkage in the range of 0 % to 10 %, preferably 0 to 5 %, an elongation at break of > 60% to 145 % as well as a high uniformity with respect to the yarn characteristics.

It is another object of the present invention to provide a device for winding multi- filament yams by the use of which yarn packages of 2 kg and more, preferably 4 kg and more, and preferably having a cheese-like shape can be obtained, wherein said multi-filament yarns comprise at least 90 weight % in relation to the total weight of the multi-filament yarns, of PBT and/or PTMT.

One additional object of the present invention consists in specifying a process for the spinning and winding of polyester multi-filament yarns which can be carried out on a large technical scale and in an economical manner. The process in accordance with the invention should permit the highest possible take-up spe ds, preferably greater than 2100 m/min. It is also one object of the present invention to improve the storability of the polyester multi-filament yarns that can be obtained by means of the process in accordance with the invention. These should also be able to be stored for a longer period of time, such as 11 weeks, for example as well as insensitive against elevated temperatures during storage and transport. A shrinlcage and a deformation of the yarn package during the storage, particularly a shrinking to such an extend that the yarn package cannot be taken off the chuck any longer, as well as the formation of bulges with hard edges, should be prevented, to the highest extent possible, so that no problems of unwinding occur during the subsequent processing of the yarn package.

In accordance with the invention, the polyester multi-filament yarns should be able to be further processed, in a simple way and manner, in a stretch or stretch texturing process, particularly at high texturing speeds, preferably greater than 450 m/min. The multi-filament yarns which can be obtained by means of stretch texturing should have outstanding material characteristics, such as a high tensile strength as well as a high elongation at break, a low amount of capillary breaks and an uniform dyeability without carriers.

These objects, as well as additional objects that are not explicitly stated but which can be simply derived or inferred from the points discussed in the present specification in an introductory manner, however, are solved by a process for the production and for the winding of polyester multi-filament yarns which consist of at least 90 weight %, in relation to the total weight of the polyester filament, of polybutylene terephthalate (PBT) and/or polytrimethylene terephthalate (PTMT), according to the present claim 1, wherein especially advantageous variations of said process are claimed in the dependent process claims. The polyester multi- filament yarns that can be obtained by means of the spinning process are described in the independent product claim whereas the device for the winding of one or more multi-filament yarns and suitable preferred embodiments of said device in accordance with the present invention are protected by the present device claims. By the application of the process of the present invention, i. e. a process for the production and for the winding of at least one polyester multi-filament yarn which consists of at least 90 weight %, in relation to the total weight of the polyester multi-filament yam, of polybutylene terephthalate (PBT) and/or polytrimethylene terephthalate (PTMT), preferably of PTMT, wherein said process is characterized in that at least one wound package of said polyester multi-filament yarns is heat- treated at a temperature in the range of > 45°C to 65°C it is possible to obtain at least one PBT and/or PTMT yam package with long-term stability during storage and which is insensitive against elevated temperatures during storage and transport. In particular said yarn package maintains its yam characteristics as well as its cheese-like shape for a longer period of time, for example 11 weeks. A shrinkage and a deformation of the yam package during the storage, particularly a shrinking to such an extend that the formation of bulges with hard edges, is not longer observed, so that no problems of unwinding occur during the processing of the yarn package.

By the provision of a device for the winding of one or more multi-filament yarns comprising a casing and a rotable spindle on which a tube may be fastened, so that said tube is placed inside said casing, wherein said device is characterized in that said the interior of said casing is heatable, it has been succeeded, in a manner that was simply not foreseeable, to provide a device by the use of which the process for the production and for the winding of polyester multi-filament yarns according to the present invention can be realized in an especially advantageous way.

The process in accordance with present invention possesses, at the same time, a series of additional advantages. These include, among others, the following:

• The process in accordance with the invention can be carried out in a simple way and manner, on a large technical scale, and economically. In particular, the process permits the spinning and winding at high take-up speeds of more than 2100 m min.

• The polyester multi-filament yarns which can be obtained by means of the process can consequently be further processed in a simple way and manner, on a large technical scale, and in an economical manner, in either a stretching- or a stretch texturing process. The texturing can thereby be carried out at speeds of greater than 450 m/min.

• Because of the high uniformity of the polyester multi-filament yarns which can be obtained by the process, it is possible to provide a cheese-like shape of the package, in a simple way, which allows a uniform and nearly defect- free surface coloring and further processing of the polyester multi-filament yarns.

• The multi-filament yams which can be obtained by means of the stretch texturing have a high tensile strength, as well as a high elongation at break.

Brief description of the drawings:

In the following the invention will be explained in greater detail, occasionally with reference to the accompanying drawings, in which

Fig. 1 is a schematic view showing a device for the winding of one or more multi- filament yarns,

Fig. 2 is a schematic view showing the shape in a normal state of a cheese-like yam package,

Fig. 3 is a schematic view showing the shape of yam package in which bulging and shrinkage has occured. Detailed description of the present invention:

The present invention relates to a device for the winding of one or more multi- filament yams comprising a casing and a rotatable spindle on which a tube may be fastened so that the tube is placed inside the casing. Thereby the rotatable spindle is a part of a winding machine. The tube is fastened on the chuck of said rotatable spindle and the multi-filament yarns are wound on said tube to form a yarn package. After the winding the tube carrying the yam package can be taken off the chuck.

According to the present invention any type of winding machine may be used as long as polyester multi-filament yarns which consist, by at least 90 weight % in relation to the total weight of the multi-filament yarns, of PBT and/or PTMT, may be wound, wherein the winding speed preferably amounts more than 2100 m/min. For further details reference is made to the technical literature, especially to the text-book "Synthetic Filaments" by F. Fourne (1995), published by the Hanser- Verlag, Munich in German.

Since the conventional winding machines known in the art allow the simultaneous winding of one or more multi-filament yams on one spindle, in particular the simultaneous winding of up to 12 multi-filament yarns, the winding device of the present invention also allows the winding of one or more, especially of one to 12, multi-filament yams at the same time in order to improve the efficiency of the spinning process.

The casing of the present invention may be made of any material known in the art. However it has proven to especially advantageous that the casing is made of a heat isolating material which preferably also provide a sound insultion. Suitable materials encompass, but are not limited to, plastics, preferably plastics having a glass transition temperature > 65°C, metals, such as stainless steel, for example, metallic alloys. Said heat isolating material may have a one or multi-layer structure comprising two, three or more layers. Preferably the heat isolating material exhibits a coefficient of thermal conduction of < 10 W/(m*K), more preferably of < 1 W/(m*K), in particular of < 0.5 W/(m*K), and most preferably of < 0.1 W/(m*K). According to an especially preferred embodiment of the present invention the heat and preferably sound insulating material has a three layered structure wherein the middle layer is made of a insulting material exhibiting a coefficient of thermal conduction of < 0.1 W/(m*K) and the outer layers are preferably made of a metal or a metallic alloy.

According to the present invention the size of the casing is preferably dimensioned in such a way that the winder is either completely encaged or at least the chuck with the maximum diameter of the tube carrying the final yarn package is encaged. It also preferably that the additional winding equipment, preferably a contact roll for control of the winding speed and preferably a traversing device is also encaged. The minimum dimensions of the casing guarantee a fault-free winding process of a high quality yarn. On the other hand it is also advantageous to minimize the size of the casing to allow a standard working environment outside said casing in the winding room and to minimize the costs required for heating the interior of said casing.The casing should preferably allow the insertion of the multi-filament yams in a simple manner, the take-off of the yarn packages in a simple manner as well as the production of yarn packages having a high weight, preferably of more than 2 kg.

According to the present invention the interior of said casing is heatable. For that purpose the interior of the casing preferably comprises one or more heating ^• elements allowing the heating of the yam package by heat conduction, heat distortion and/or head radiation. Especially preferred heating elements in the sense of the present invention encompass but are not limited to heated rolls and/or heat or thermal radiators. According to one especially preferred embodiment of the present invention the device for the winding of one or more multi-filament yarns comprises a contact- roll for controlling the winding speed, wherein said contact-roll is located inside the casing and is heatable. Thereby it is possible to measure and control the winding speed and to heat-treat the yarn package at the same time.

According to another especially preferred embodiment of the present invention the interior of the casing is heated by the use of a heated gas which is preferably ^■ supplied through at least one inlet for gases into said casing. Furthermore said casing preferably also comprises at least one outlet for gases out of said casing, wherein said inlet and said outlet are preferably connected in such a manner, that said gases can be circulated. In that context it has been proven to be especially advantageous that said inlet and said outlet are arranged so that in view of the moving direction of the yam said gases may be supplied behind and may be drawn off before said tube fastened on said rotatable spindle. The gases are preferably heated outside the casing, to assure a constant temperature distribution in the interior of the casing.

The temperature inside the casing may be measured by the use of one or more means for measuring the temperature comprised inside said casing. Thereby it is especially preferred that the casing also comprises at least one inlet for gases into said casing and means for heating said gases, preferably outside the casing, wherein said means for measuring the temperature inside the casing and said means for heating said gases are preferably connected so that the temperature inside said casing may be controlled to a temperature inside a predetermined temperature range, preferably in the range of >45°C to 65°C. According to one especially preferred embodiment of the present invention the temperature inside the casing is measured by means for measuring the temperature, compared with the predetermined value and depending on the temperature deviation the temperature of the hot air is suitable adapted (raised, lowered or maintained), so that the temperature inside said casing falls within the desired temperature range. Furthermore it may also be advantageous that two and/or more means for measuring the temperature are arranged in the interior of the casing to determine the temperature distribution inside the casing and to assure a homogeneous temperature distribution to the highest extend possible by suitable adaption of the temperature of the heated gases as well as of their flow rates.

For the insertion of the multi-filament yams before the start of the winding procedure the device according to the present invention preferably comprises an opening, wherein an opening in the form of a slit is especially preferred. The slit is preferably arranged so that said multi-filament yams may be inserted transversally to the moving direction of the yarn and advantageously the slit may be partially covered by suitable means for the purpose of isolating the interior from the outside so that any possible gradient of the temperature inside the casing is avoided to the highest extend possible. According to one especially preferred embodiment of the present invention the covering is provided in the form of a flap which may partially cover the slit during the spinning and winding process and which may be opened in order to insert the multi-filament yarns transversally to the moving direction of the yarn. Thereby the flap preferably comprises one or more recesses through which the multi-filament yams may enter the casing when the flap is closed, wherein the position and the size of the one or more recesses is suitably selected depending on the traverse length of the yam package.

The device for the winding of one or more multi-filament yams according to the present invention preferably comprises a traversing device to control the specific shape of the yam package. Thereby the present invention is not limited to the use of special types of traversing devices by the way of contrast any type of trans versing device known in the art may be used as long as the objects of the present invention are achieved. Although the position of the traversing device is not restricted by the present invention, for example, it may be located out said casing, preferably right in top of the opening for inserting the multi-filament yarns into the casing, wherein the opening is preferably provided in the form of a slit covered by a flap comprising one or more recesses provided in the form of a slit extending in parallel to the tube. The length of the recess slit(s) is suitably chosen depending on desired traverse length. However the traversing device is preferably located inside the casing and preferably arranged before the tube on which the multi-filament is wound up in view of the moving direction of the yarn. Thereby it is possible to minimize the size of the opening, preferably provided in the form of a slit covered by a flap comprising one or more recesses, so that the occurance of a temperature gradient inside the casing is suppressed to the highest extend possible. According to an especially preferred embodiment of the present invention said one or more recesses provide small holes when the flap is closed, wherein the size of the holes is preferably adapted to the thickness of the multi-filament yarns.

To take-off the yarn package the device according to the present invention suitably may be opened, wherein it is especially preferred that this opening is provided in the form of a closable opening which may be closed during the spinning and winding process to assure a constant temperature inside the casing. An especially preferred embodiment of said closable opening is a door which may be opened to insert the multi-filament yams or to take-off the resulting yarn packages and which may be closed during the spinning and winding process. Thereby the closable opening is preferably provided at the front end of said casing.

In Fig. 3 there is shown schematically a preferred embodiment of the device according to present invention. The device 2 for winding one or more multi- filament yams comprises a casing 4. In the shown embodiment the casing 4 has the form of a casing with a bottom wall 6, a top wall 8, two side walls 10, 12, a front wall 14 and a rear wall 16, the top wall 8 facing the incoming multi-filament yarns. The front wall 14 has the function of a door, i. e. the casing 4 may be opened or closed by the front wall 14. At the rear wall 16 outside the casing 4 there is provided a driving unit 18.

An opening 20 is provided in the top wall 8 having the form of a slit which extends from the front wall 14 towards the rear wall 16 and which is parallel to the side walls 10, 12. Said opening 20 is partially covered by a flap 22 comprising recesses 24 allowing the multi-filament yarns 26 to enter the casing 2 via the opening 20. Since the opening 20 extends to the front wall 14 multi-filament yams 26 may be inserted from the side of the casing 2 when the front wall 14 and the flap 22 is opened.

In the moving direction of the multi-filament yams 26 which is indicated by arrow A in Fig. 3 behind the opening 20 there is arranged a traversing unit 28 inside the casing 4. The traversing unit 28 is interconnected with and driven by the driving unit 18 at the rear wall 16. In view of the moving direction A of the multi-filament yarns 26 a tube 30 fastened on a chuck of a rotatable spindle is arranged behind the traversing unit 28 inside the casing 2. The tube 30 extends from the rear wall 16 toward the front wall 14 in parallel to the top wall 8. The spindle is connected to the driving unit 18 so that the spindle and the tube 30 fastened on said spindle may be rotated around its axis during operation of the driving unit 18.

Inside the casing 4 there is at least one sensor- in the figure 3 there are two sensors 32 - for measuring the temperature inside of the casing and controlling the heat flow, wherein one of said sensors 32 is arranged behind the tube 30 the other sensor is arranged in front of the tube 30 in view of the moving direction A of the multi-filament yams 26.

The casing 4 further comprises an outlet 34 arranged in the top wall 8 and an inlet 36 arranged in the rear wall 16, i. e. the outlet 34 is arranged in front of the tube 30 and the inlet 36 is arranged behind the tube 30 in view of the moving direction A of the multi-filament yarns 26. The outlet 34 can be optionally connected with a heating and blowing unit 38 via a conduct 40 represented by a broken line in Fig. 3 to circulate the hot gas and minimize process costs. The inlet 36 is connected with the heating and blowing unit 38 via a conduct 42. The heating and blowing unit 38 heats a gas, for example air, and blows said gas in the direction indicated by the arrows B in Fig. 3 so that the gas is circulated through the casing 4. The temperature in the area in which the tube is arranged can be controlled by controlling the output of the heating and blowing unit 38 on the basis of the values measured by the sensors 32.

In the following the functioning of the afore-described device 2 according to the invention will be described. First of all, the multi-filament yarns 26 have to be strung, preferably by air suction gun, to the tube fastened on the chuck 30 to form the yarn packages. For this reason the front wall 14 and the flap 22 have to be opened, so that the multi-filament yarns 26 can be inserted in the slit-like opening 20. After the insertion of the multi-filament yarns 26 in the opening 20 and the traversing unit 28 and after their fixation on the tube the front wall 14 and the flap 22 can be closed again so that each mult-filament yarn runs through its separate recess 24 of the flap, the recesses 24 each having a width corresponding with the width of the one single multi-filament yam 26. Afterwards the tube 30 fastened on the spindle and the traversing unit 28 are driven by the driving unit 18 so that the yarn packages 44 are produced.

During the winding of the multi-filament yarns 26 a heated gas is conducted into the casing 4 via inlet 36. to heat up the casing and the yarn packages 44 on the tube 30s. The heated gas is exhausted to the heating and blowing unit 38 via the outlet 34, thereby providing a preselected temperature of the yarn packages 44 and the filaments 26.

The afore-described device for the winding of multi-filament yams may be used for winding of any type of multi-filament yams known in the art. Suitable multi- filament yams encompass but are not limited to those which comprise at least 90 weight % of polyesters, such as polyethylene terephthalte, PBT and/or PTMT, and/or polyamides, such as nylon-6 and/or nylon 6,6. However the device for winding of multi-filament yarns according to the present invention is preferably use for the winding of polyester multi-filament yams which consist, at least by 90 weight % in relation to the total weight of the polyester multi -filament yams, 'of polybutylene terephthalate (PBT) and/or polytrimethylene terephthalate (PTMT).

Therefore, according to another aspect the presention invention also refers to a process for the production and for the winding of at least one polyester multi- filament yam which consists, at least by 90 weight % in relation to the total weight of the polyester multi-filament yam, of polybutylene terephthalate (PBT) and/or polytrimethylene terephthalate (PTMT). Polybutylene terephthalate (PBT) and/or polytrimethylene terephthalate (PTMT) are already known in the art. Polybutylene terephthalate (PBT) can be obtained by the polycondensation reaction of terephthalic acid with equimolar quantities of 1,4-butanediol, while polytrimethylene terephthalate can be obtained by the polycondensation reaction of terephthalic acid with equimolar quantities of 1,3-propanediol. Mixtures of both polyesters are also conceivable. In accordance with the invention, the use of PTMT is especially preferred.

The polyesters can be both homopolymers as well as copolymers. Suitable examples of copolymers encompass but are not limited to those which contain, in addition to the repeating PTMT and/or PBT units, an additional amount of up to 15 mol. %, in relation to all repeating units of the polyester, of repeating units of normal comonomers, such as ethylene glycol, diethylene glycol, triethylene glycol, 1,4-cyclohexanedimethanol, polyethylene glycol, isopthalic acid, and/or adipinic acid, for example. In the present invention, however, the use of polyester homopolymers is especially preferred.

The polyesters in accordance with the invention can contain normal quantities of additional additives as admixtures, such as catalysts, stabilizers, antistatic agents, antioxidants, flame retarding agents, colorants, colorant absorption modifiers, light stabilizers, organic phosphites, optical brighteners, and matting agents. The polyesters preferably contain from 0 to 5 weight % of additives, in relation to the total weight of the multi-filament yam.

The polyesters that are usable in the sense of the present invention are, preferably, thermoplastically formable and can be spun into filaments. Polyesters that have a intrinsic viscosity in the range from 0.70 dl/g to 0.95 dl/g are thereby particularly advantageous.

The process of the present invention is not restricted to a special type of spinning process; by the way of contrast any conventional type of spinning process known in the art may be employed. Therefore, even though an especially preferred spinning process in accordance with the present invention is described below, reference is made to the common technical literature, especially to the textbook "Synthetic Filaments" by F. Fourne (1995), published by Hanser-Verlag, Munich (in German), for the specific details of said process.

In the process in accordance with the invention, the melt or mixture of melts of the polyester is pressed into nozzle assemblies and extruded through the nozzle apertures of the nozzle plate of the assembly and into molten filaments by means of a spinning pump at constant rotational speed, wherein the rotational speed is adjusted in accordance with known computation formula in such a manner that the desired thread titer is achieved.

The melts can, for example, be produced in an extruder from polymer chips, whereby it is particularly favorable to dry the chips in advance to a water content of < 30 ppm, particularly to a water content of < 15 ppm. The extruded filaments are subsequently cooled to temperatures below the solidification temperature. For the purposes of the invention, the solidification temperature is the temperature at which the melt passes into the solid state.

According to the present invention, it has proven to be particularly suitable to cool the filaments to a temperature at which they are essentially not sticky any longer. A cooling of the filaments to temperatures below their crystallization temperature, particularly to temperatures below their glass temperature, is particularly advantageous.

Means for quenching or cooling filaments are known from the prior art.

The filaments are bundeled in an oiler pin which supplies the yam with the desired amount of spin finish at a uniform rate.

According to the invention, the multi-filament yarns are preferably entangled before being wound up.

The bundeled yams are drawn off by the use ofa first godet system and guided to the winder. Further godet systems can be employed before the yarn is wound up in the winder assembly to form packages on the tube. The optional further godet systems are included for drawing, thermosetting and relaxation of the yarn.

According to the present invention the polyester multi-filament yams are preferably heat-treated at a temperature in the range of 50 to 150 °C prior to their winding, wherein said heat-treatment may be accomplished by any type of method known in the art.

According to one especially preferred embodiment of the present invention the polyester filaments are heat-treated by the use of heated godets. Suitable godets encompass but are not limited to those generally described in the textbook "Synthetic Filaments" by F. Fourne (1995), published by Hanser-Verlag, Munich (in German).

According to another preferred embodiment of the present invention the polyester filaments are heat-treated by the use of heated gases, especially heated air.

According to another preferred embodiment of the present invention the polyester filaments are heat-treated by the use of radiation heat.

The heat-treatment of the polyester filaments may also be accomplished by guiding the thread in close proximity but essentially without contact along an longitudinally extended heating surface, wherein a suitable type of a heat- treatment of this kind is described in the patent document EP 731 196, for example.

Stable, defect-free packages are a basic prerequisite for defect-free unwinding of the yarn and for an ideally defect-free further processing. In the context of the present invention, during the winding the wound package of said polyester multi- filament yams is heat-treated at a temperature in the range of > 45°C to 65°C. Thereby said heat-treatment may be carried out by any type of method known in the art. Suitable methods encompass but are not limited to methods wherein the principle of the heating of the wound package is based on heat conduction, heat convection and/or heat radiation. According to an especially preferred embodiment of the present invention said package is heat-treated by the use of heated rolls, preferably by the use of heated contact rolls which simultaneously measure and control the winding speed. According to another especially preferred embodiment of the present invention is heat-treated by the use of radiation heat.

According to a further especially preferred embodiment of the present invention said package is heat-treated by the use of heated gases, such heated air and inert gases, such as nitrogen, helium and/or argon. The use of heated air is especially preferred in the context of the present invention. The temperature of the heated gases is preferably suitably adapted to ensure that the temperature inside the casing falls within the range of >45°C to 65°C. Therefore according to an especially preferred embodiment of the present invention the temperature of the gases is in the range from >45°C to 65°C. The relative humidity of the gases is preferably in the range of 40 to 90%. The flow rate on the gas inlet of the casing is in the range from 5 to 100 m³ h.

The heat-treatment of the package is preferably carried out by the use of a winding device as described above, wherein the tube may be fastened on the rotatable spindle of the winder, so that the tube is encaged inside a casing. The gas (or gases) is preferably supplied into said casing through an inlet and preferably drawn off said casing through an outlet, wherein the inlet and the outlet preferably are connected to form a circuit so that said gas is circulated in a circuit comprising said inlet and said outlet. In that context it has proven to especially advantageous to supply the gas behind and to draw off said gas before said tube in view of the moving direction of the yam. Even though the gas may also be heated inside the casing said heating is preferably performed outside the casing.

According to the present invention it is preferable to measure the temperature inside the casing and to adjust the temperature of the gas by suitable heating so that the temperature inside the casing falls within the range of >45°C to 65°C. Thereby it is especially preferred that the temperature inside the casing is measured at at least two different locations inside the casing, preferably before and behind the tube in view of the moving direction of the yarn, to verify and ensure that the temperature inside the casing is constant. The occurance of a temperature gradient should be avoided by suitable adaption of the gas temperature and/or its flow rate.

The shape of the package is preferably controlled by the use of a traversing device, which may be located either outside or inside the casing. However, it is especially advantageous to controll the shape of the package by the use of a , traversing device located inside the casing which is arranged before said tube in view of the moving direction of the yam. By the use of this very preferred embodiment of the present invention the size of the opening through which the filaments are guided into the winding device can be minimized so that the occurance of a temperature gradient inside the casing is suppressed to the highest extend possible.

The process of the present invention allows the manufacture of yarn packages having a cheese-like shape, as schematically shown in Fig. 1. A shrinkage and a deformation of the yam package during the storage, particularly a shrinking to such an extend that the yam package cannot be taken off the chuck any longer, as well as the formation of bulges with hard edges, as schematically shown in Fig. 2, is not longer observed, so that no problems of unwinding occur during the subsequent processing of the yam package. Thereby the polyester packages obtainable by the present method exhibit an improved long-term stability during storage and are insensitive against elevated temperatures during storage and transport. In particular they maintain their favourable characteristics and cheeselike shape even during storage for a longer period of time, for example for 11 weeks.

To set the winding tension according to the invention, the winding speed of the POY is advantageously 0-2% below the take-up speed. It is preferable to select a winding speed to be 0-1% below the spinning take-up speed. The take-up speed preferably is > 2,100 m/min, more preferably in the range of 2,500 to 6,000 m/min, especially in the range of 3,500 to 6,000 m/min.

The polyester multi-filament yams obtainable by the present method exhibit superior properties compared with those of the prior art. Preferably they exhibit an elongation at break in the range of > 60 % to 145 % and a boil-off shrinkage in the range of 0 to 10 %, especially in the range of 0 to 5 %. They allowing subsequent processing in a simple manner, on a large technical scale, and in an economical manner, in either a stretching- or a stretch texturing process. The texturing can thereby be carried out at speeds of greater than 450 m/min. The multi-filament yarns which can be obtained by means of the stretch texturing have a high tensile strength, as well as a high elongation at break, low capillary breaks and uniform dyeability at boiling temperature.

Analytical methods for determining the material parameters reported are well known to a person skilled in the art. They are discernible from the technical literature, for example from WO 99/07927, the disclosure of which is hereby expressly incorporated herein by reference.

The intrinsic viscosity is measured at 25°C in the capillary viscosimeter from the firm Ubbelohde, and computed in accordance with a known formula. A mixture of phenol / 1 ,2-dichlorobenzol is used as a solvent in the weight ratio of 3 : 2. TLe concentration of the solution amounts to 0.5 g polyester to 100 ml of solution.

A DSC calorimeter device from the firm Mettler is used for the determination of the melting point, and for the temperature of crystallization and glass. In this, the sample is thereby first heated up to 280°C and melted, and then suddenly chilled. The DSC measurement is carried out in the range from 20°C to 280°C, with a heat rate of 10 K/min. The temperature values are determined by the processor.

The determination of the density of the filaments is carried out in a density / gradient column at a temperature of 23 ± 0.1°C. For reagent, n-heptane (C₇H_](:) and tetrachloromethane (CCI₄) are used. The result of the density measurement can be used for the calculation of the degree of crystallization, since the density of the amorphous polyester D_a and the density of the crystalline polyester D_k are taken as the basis. The corresponding computation is known from the literature; for example, the following is valid for PTMT: D_a = 1.295 g/cm³ and D_k = 1.429 g/cm³. The titer is determined in the known manner by means of a precision reeling machine and a weighing device. The prestressing thereby suitably amounts to 0.05 cN/dtex for filaments , and to 0.2 cN/dtex for textured threads (DTY).

The tensile strength and the elongation at break are determined in a Statimat measuring device with the following conditions: the clamping length amounts to 200 mm for POY or 500 mm for DTY, respectively; the measuring speed amounts to 2000 mm/in. for POY or 1500 mm/min. for DTY, respectively; and the prestressing amounts to 0.05 cN/dtex for POY or 0.2 cN/dtex for DTY, respectively. The tensile strength is determined by dividing the values for the maximum breaking load by the titer, while the elongation at break is evaluated at the maximum load.

For the determination of the boil-off shrinkage, strands of filaments are treated, in a tension-free manner, in water at 95 ± 1°C for 10 ± 1 min. The strands are produced by means of a reeling machine with a prestressing of 0.05 cN/dtex for POY or of 0.2 cN/dtex for DTY; the measurement of the length of the strands before and after the temperature treatment is carried out at 0.2 cN/dtex. The boil- off shrinkage is evaluated in the known manner from the differences in lengths.

The normal uster values are determined with the 4-CX Uster Tester and stated as uster % values. At a test speed of 100- m/min., the test time for this amounts to 2.5 min.

The invention will be illustrated in the following by means of examples and a comparative example, without the invention having to be restricted to these examples. Example 1

Corterra-type crystalline PTMT chips (Shell Oil Company (USA)) with an intrinsic viscosity of 0.94 dl/g, a crystallization temperature of 72°C, and a glass transition temperature of 45°C, were dried in a toumble dryer at a temperature of 130°C to a water content of 11 ppm. The chips were melted in a 3E4 extruder from the firm Barmag, so that the temperature of the melt amounted to 254°C. The melt was then conveyed to the spinning pump through a product line and fed fed to a spinning pump wherein the melt throughput to the spin pack was controlled to 76.1 g/min. The melt was extruded through a nozzle plate 80 mm in diameter, with 48 holes 0.25 mm in diameter and a length of 0.75 mm. The nozzle pressure amounted to approximately 120 bar.

Subsequently to that, the filaments were cooled off in a blowing shaft with a crossflow quench system having a length of 1500 mm. The cooling air had a speed of 0.55 m/sec, a temperature of 18°C, and a relative humidity of 80%. The filaments were provided with spinning preparation and bundled with the help of an oiling device at a distance of 1500 mm from the nozzle. The oiling device was provided with a TriboFil surface. The quantity of preparation applied amounted to 0.40% in relation to the weight of the thread.

Thereafter the bundled multi-filament yarns were heat-treated by the use of a godet system consisting of two duos heated to 100°C, wherein the multi-filament yarns loop each duo five times. The take-up speed at the first duo amounted to 2,987 m/min and the take-up speed at the second duo amounted to 3,000 m/min.

Finally the heat-treated multi-filament yams were wound on a type SW6 winder (BARMAG (Germany)) at a winding speed of 3,075 m/min. The tube fastened on the spindle of the winder was encaged in a casing having a slit-like opening for the multi-filament ya s. The temperature inside the casing was 49°C controlled by a supply of heated air with a flow rate of 30 m³/h, wherein the amount of heated air supplied into the casing matched the amount of air drawn off. The room climate was set at 24°C at 60% relative humidity.

By the present method cheese-like yam packages of 14 kg have be produced, which could be taken off the chuck without problems. A part of said packages was stored in a heating chamber for 20 hours at a temperature of 60°C to simulate a transport of said package. Another part of the packages was stored in a storing room for 11 weeks at a temperature of about 24°C. A comparison of the shape of the packages and of the multi-filament yams characteristics (see Table 1) revealed that the present multi-filament yams exhibited a high storage stability without significant worsening of the material characteristics. The multi-filament yams of Example 1 having a titer of 248 dtex have been stretch-textured in an additional step.

Table 1: Materials characteristics of the Example 1

coefficient of variation of the elongation at break Comparative Example

Example 1 was repeated except that the quantity of melt that was transported amounted to 78.0 g/min and that a multi-filament yam having a titer of 199 dtex has been produced. Furthermore a S-wrapped pair of non-heated godets was used instead of the heated Duos, wherein the take-up speed at the first godet and the second godet amounted to 4,000 m/min and 4,012 m/min, respectively. Finally the multi-filament yarns were wound at a winding speed of 3,968 m/min on a conventional winder not encaged in a casing.

After the winding of about 2 kg a significant shrinkage of the yarn package as well as the formation of bulges were observed, so that the winding process had to be stopped to avoid damaging of the chuck. The observed material characteristics are summarized in table 2.

Table 2: Materials characteristics of the Comparative Example

: coefficient of variation of the elongation at break

Example 2 and 3

Example 1 was repeated except that the melt throughput was changed. Furthermore a S-wrapped pair of non-heated godets was used instead of the heated Duos. Similarly to Example 1 the multi-filament yams were wound on a type SW6 winder (BARMAG (Germany)); wherein the tube fastened on the spindle of the winder and carrying the yarn package was encaged in a casing having a slit- like opening for the multi-filament yams. The temperature inside the casing was 63 °C controlled by a supply of heated air, wherein the amount of heated air supplied into the casing matched the amount of air drawn off. The room climate was set at 24°C at 60% relative humidity. The exact settings of the Examples 2 and 3 are shown in table 3.

Table 3: Test parameters of the Examples 2 and 3

By the present method cheese-like yarn packages have be obtained, which could be taken off the chuck without problems. A part of said packages was stored in a heating chamber for 20 hours at a temperature of 60°C to simulate a transport of said package. Another part of the packages was stored in a storing room for 4 weeks at a temperature of about 24°C. A comparison of the shape of the packages and of the yams characteristics (see Table 5) revealed that the present multi- filament yarns exhibited a high storage stability without significant worsening of the material characteristics.

Table 4: Materials characteristics of the Example 2

Table 5: Materials characteristics of the Example 3

: coefficient of variation of the elongation at break

Claims

Patent Claims:

1. A process for the production and for the winding of at least one polyester multi-filament yam which consists of at least 90 weight %, in relation to the total weight of the polyester multi-filament yam, of polybutylene terephthalate (PBT) and/or polytrimethylene terephthalate (PTMT), preferably of PTMT, to provide at least one yam package with long-term stability during storage and which is insensitive against elevated temperatures during storage and transport, wherein said process is characterized in that the wound package of said polyester multi-filament yarn is heat-treated at a temperature in the range of > 45°C to 65°C.

2. A process according to claim 1 characterized in that said package is heat- treated by the use of heated rolls.

3. A process according to claim 1 characterized in that said package is heat- treated by the use of radiation heat.

4. A process according to claim 1 characterized in that said package is heat- treated by the use of heated gases.

5. A process according to claim 1 characterized in that said package is heat- treated inside a casing encaging a tube fastened on a rotatable spindle and carrying the yam package.

6. A process according to claim 5 characterized in that a gas is supplied into said casing through an inlet.

7. A process according to claim 6 characterized in that said gas is drawn off said casing through an outlet.

8. A process according to claim 7 characterized in that said gas is circulated in a circuit comprising said inlet and said outlet.

9. A process according to claim 7 characterized in that in view of the moving direction of the yam said gas is supplied behind and drawn off before said tube.

10. A process according to claim 6 characterized in that said gas is heated outside said casing.

11. A process according to claim 10 characterized in that the temperature inside said casing is measured and the temperature of said gas is adjusted by suitable heating so that the the temperature inside said casing falls within the range of >45°C to 65°C.

12. A process according to claim 5 characterized in that the shape of said package is controlled by the use of a traversing device inside said casing which is arranged before said tube in view of the moving direction of the yarn.

13. A process according to claim 1 characterized in that said package has a cheese-like shape.

14. A process according to claim 1 characterized in that said at least one polyester multi-filament yam is heat-treated at a temperature in the range of 50°C to 150°C prior to its winding.

15. A process according to claim 13 characterized in that said at least one polyester multi-filament yam is heat-treated by the use of heated godets.

16. A process according to claim 13 characterized in that said at least one polyester multi-filament yam is heat-treated by the use of heated gases.

17. A process according to claim 13 characterized in that said polyester filaments are heat-treated by the use of radiation heat.

18. A process according to claim 1 characterized in that the take-up speed is adjusted to between 2500 m/min and 6000 m/min.

19. A polyester multi-filament yam which consists of at least 90 weight %, in relation to the total weight of the polyester multi-filament yarn, of polybutylene terephthalate (PBT) and/or polytrimethylene terephthalate (PTMT), preferably of PTMT, obtainable by a process according to claim 1 characterized in that, its elongation at break is in the range of > 60 % to 145 % and its boil-off shrinkage is in the range of 0 to 10 %.

20. A device (2) for the spooling of one or more multi-filament yams (26) comprising a casing (4) and a rotatable spindle on which a tube (30) may be fastened, so that said tube (30) is fastened inside said casing (4), characterized in that the interior of said casing (4) is heatable.

21. A device (2) according to claim 20, characterized in that said casing (4) comprises at least one inlet (36) for gases into said casing (4).

22. A device (2) according to claim 21, characterized in that said casing (4) comprises at least one outlet (34) for gases out of said casing.

23. A device (2) according to claim 22, characterized in that said inlet (36) and said outlet (34) are connected in such a manner, that said gases can be circulated.

24. A device (2) according to claim 22, characterized in that said inlet (36) and said outlet (34) are arranged so that in view of the moving direction (A) of the yam said gases may be supplied behind and may be drawn off before said tube (30).

25. A device (2) according to claim 21, characterized in that said device (2) comprises means for heating (38) said gases outside said casing (4).

26. A device (2) according to claim 20, characterized in that said device (2) comprises one or more means for measuring the temperature (32) inside said casing (4).

27. A device (2) according to claim 26, characterized in that said casing (4) comprises at least one inlet (36) for gases into said casing (4) and means for heating (38) said gases wherein said means for measuring the temperature (32) inside the casing (4) and said means for heating (38) said gases are comiected so that the temperature inside said casing (4) may be controlled to a temperature inside a predetermined temperature range.

28. A device (2) according to claim 20, characterized in that said device (2) comprises an opening (20) for the insertion of said at least-one multi-filament yarn (26).

29. A device (2) according to claim 28, characterized in that said opening (20) has the form of a slit.

30. A device according to claim 29, characterized in that said slit is arranged so that said at least one multi-filament yam (26) may be inserted transversally to the moving direction (A) of the yam.

31. A device (2) according to claim 29, characterized in that said device (2) comprises means for the partial covering of said slit (22).

32. A device (2) according to claim 20, characterized in that said device (2) comprises a traversing device (28) inside said casing (4) which is arranged before said tube (30) in view of the moving direction (A) of the yam.

33. A device (2) according to claim 20, characterized in that said device (2) may be opened to take-off the yam package (44).

34. A device (2) according to claim 20, characterized in that said rotatable spindle is arranged inside said casing (4).