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(11) | EP 1 482 077 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Polyester multi-filament yarns, process for their production and winding and winding device |
| (57) The present invention refers to 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 yarn, 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
polyester comprises an infrared absorbing pigment and/or a catalyst having infrared
absorbing properties and that the polyester multi-filament yam is heat-treated by
the use of infrared radiation during winding to a yarn package. In addition the present invention relates to said polyester multi-filament yam 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 %. The present invention also claims a device for the winding of one or more multi-filament yams (3) comprising a commercial winder and at least one infrared radiant heater (9) arranged in a defined distance from the winder shaft (4) thereby irradiating a yarn package (5) which is placed on said winder shaft (4). |
Technical field:
[0001] 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 yams which can be obtained by means of the process and a device for the winding of one or more multi-filament yarns.
Background Art:
[0002] The production of continuous polyester multi-filament yarns, particularly polyethylene terephthalate (PET) multi-filament yams, in a two-stage process, is already known. In this, multi-filament yams are spun and wound during the first stage, which multi-filament yams are, during a second stage, stretched into finished form and thermofixed, or else stretch-textured into bulky multi-filament yams. Between the two stages, the packages of the multi-filament yams 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.
[0003] The textbook "Synthetic Filaments" by F. Fourné (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.
[0004] However, the exact design of the spinning and winding machine as well as the spinning and winding process cannot be taken from that textbook. Therefore it still remains the task to be solved by the specialist to develop the exakt design of the spinning and winding machine as well as the spinning process depending on the polymers to be used and the properties of the yam aimed at.
[0005] In contrast to PET multi-filament yams, polytrimethylene terephthalate (PTMT) or polybutylene terephthalate (PBT) multi-filament yams 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 yams. The yarn 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 yam characteristics, such as extreme increase of uster values. Only the limitation of the weight of the yam packages to less than 2 kg provides a remedy for these problems which normally do not occur during the processing of PET yams.
[0006] Furthermore, it has been observed that, in contrast to PET multi-filament yams, PBT multi-filament yams or PTMT multi-filament yams age to an increased degree during storage. A structural hardening appears, changing the characteristics of the multi-filament yams (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 yams with constant characteristics.
[0007] 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 Dombim. 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.
[0008] 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 B1. 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 yarns 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 yams. In addition the final yams will exhibit an insufficient low elongation at break.
[0009] WO 01/04393 refers to a process wherein the multi-filament yams 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 yam packages.
[0010] The European patent EP 0 731 196 B1 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 a 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 yam package is not described in that document. Besides neither the stability in storage nor the stability during transport of the yam packages is stated.
Disclosure of the invention:
[0011] 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 yams 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 yams in a simple way and manner. In particular, the polyester multi-filament yams 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 yam characteristics.
[0012] 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 having a cheese-like shape can be obtained, wherein said multi-filament yams comprise at least 90 weight % in relation to the total weight of the multi-filament yams, of PBT and/or PTMT.
[0013] One additional object of the present invention consists in specifying a process for the spinning and winding of polyester multi-filament yams 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 winding speeds, preferably greater than 2100 m/min.
[0014] It is also one object of the present invention to improve the storability of the polyester multi-filament yams 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 15 weeks and more, for example as well as insensitive against elevated temperatures during storage and transport. A shrinkage and a deformation of the yam package during the storage should be prevented. A shrinking during winding 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, should be prevented, to the highest extent possible, so that no problems of unwinding occur during the subsequent processing of the yam package.
[0015] In accordance with the invention, the polyester multi-filament yams 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 yams 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.
[0016] 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 yams 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 yams 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 yams and suitable preferred embodiments of said device in accordance with the present invention are protected by the present device claims.
[0017] 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 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, wherein said process is characterized in that the polyester comprises an infrared absorbing pigment and/or a catalyst having infrared absorbing properties, wherein said pigment and/or catalyst enhances the infrared absorption properties of the yam, and that the polyester multi-filament yam is heat-treated by the use of infrared radiation during winding to a yam package, 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 yam package maintains its yam characteristics as well as its cheese-like shape for a longer period of time, for example 15 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 yam package.
[0018] Another aspectus of the invention is to reduce the amount of radiation energy to heat up the multi filament yam to a preselected defined temperature by using a yam comprising an efficient infrared absorbing pigment and/or a catalyst with infrared absorbing properties Additionally it was found, that the infrared radiation of the surface filaments during winding of the package influences the reorientation of the polymer chain forces and the resulting POY package stabilization so that lower temperatures can be employed compared to other heating methods of the package e.g. by air in a casing surrounding the winder.
[0019] The invention can preferably be applied for the production of deeper colored yams but also for delustered or bright yams.
[0020] By the provision of a device for the winding of one or more multi-filament yams comprising a commercial winder, characterized in that at least one infrared radiant heater is arranged in a defined distance from the winder shaft of said commercial winder, 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 yams according to the present invention can be realized in an especially advantageous way.
[0021] 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 winding speeds of more than 2100 m/min.
- The polyester multi-filament yams 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 yams 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 yams.
- 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.
Brief description of the drawings:
[0022] 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 yams,
Fig. 2 is a schematic view showing a device for the winding of one or more multi-filament yarns wherein the device comprises a casing,
Fig. 3 is a schematic view showing the shape in a normal state of a cheese-like yarn package,
Fig. 4 is a schematic view showing the shape of yam package in which bulging and shrinkage has occured.
Detailed description of the present invention:
[0023] The present invention relates to a device for the winding of one or more multi-filament yams comprising a commercial winder and at least one infrared radiant heater arranged in a defined distance from the winder shaft. A defined distance means that the distance from the heater to the winder shaft is sufficient to allow the winding of a yam package onto said winder shaft until the desired size of the yam package is reached. In a preferred embodiment of the present invention, the distance between the heater and the winder shaft is 150 - 750 mm. The yam package extends between the winder shaft and the heater. During the winding process, the radial extension of the yam package increases. When the maximium yam load of the package is reached, the distance between the package surface of the maximum yam load package and the infrared heater is at least 25 mm. The arrangement of the infrared radiant heater is designed in a way not to impeed the package handling. The arrangement of the heater allows the insertion of multi-filament yams in a simple manner. The take-off of the yam packages in a simple manner is possible as well as the production of yam packages having a high weight, preferably of more than 2 kg.
[0024] Said infrared radiant heater directly and/or indirectly irradiates a yam package which is placed on the winder shaft during the winding process. Preferably the radiant heater directly irradiates the whole surface of a yam package with infrared radiation.
[0025] Thereby the present invention is not limited to the use of special types of infrared radiant heaters. The heaters comprise electric elements, gas-fired elements and ceramic elements with different geometries and power stages as well as infrared lamps, such as Nernst-lamps, infrared tubes, infrared lasers and infrared diodes. In a preferred embodiment, the infrared heater comprises an infra-read heating tube which is located in a defined distance parallel to the winder shaft. Said tube is going parallel to at least that part of the winder shaft where a yarn package is placed. Thereby the whole surface of the yarn package can be irradiated.
[0026] The winder shaft is a part of a commercial winder. The term "yarn package on a winder shaft" means in detail that a yam carrying tube is fastened on the chuck of said winder shaft and the multi-filament yarn is wound on said tube to form a yam package. After the winding the tube carrying the yarn package can be taken off the chuck and the winder shaft respectively. The tube for carrying the yarn package and the chuck are not shown in the figures.
[0027] In a preferred embodiment the infrared radiant heater comprises an infrared heating tube which is fixed in a frame, whereas the support of the tube is mounted on a pivot to allow the variation of the distance to the surface of the winding package. Usually, the distance from the infra red heating tube or another type of infrared heater to the winding shaft is held constant during the winding process. Accordingly, the distance from the heater/ the infrared tube to the surface of the yarn package decreases during the winding process. In any case, the distance between the package surface of the maximum yam load package at the end of the winding process and the heating tube/ the heater is at least 25 mm. In the understanding of the present invention, it is also possible to vary the position of the heater/the heating tube during the winding process. In result, the distance between the heater and the surface of the yam package can be held constant by changing the distance from the heater to the winder shaft during the winding process.
[0028] In the understanding of the present invention one or more infrared radiant heaters are mounted in the described way beneath the winder shaft and the yam package. In a preferred embodiment one or more infra red tubes are mounted parallel to the winder shaft.
[0029] The temperature during the heat treatment of the yam can be measured at or near the surface of the winding package by the use of one or more means for measuring the temperature as thermal-optical sensors or infrared sensors. Such means are preferably arranged in a distance of 25-250 mm to the package surface of the maximum yam load. Said means for measuring the temperature are connected with an electronical measurement and control system and the infrared radiant heater to control the selected temperature during winding. The temperature at or near the surface of the yarn package can be controlled by the afore described electronical mesurement and control system in a predetermined temperature range, preferably in the range of ≥ 35°C to 65°C. Usually, the temperature is held constant.
[0030] Furthermore it might also be advantageous that two or more means for measuring the temperature are arranged at a defined distance to the package surface to determine the temperature distribution at or near the surface of the package to assure a homogeneous temperature distribution to the highest extend.
[0031] According to the present invention any type of winding machine may be used as long as polyester multi-filament yams 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. Fourné (1995), published by the Hanser-Verlag, Munich in German.
[0032] Since the conventional winding machines known in the art allow the simultaneous winding of one or more multi-filament yams on one winder shaft, in particular the simultaneous winding of up to 12 multi-filament yams, the winding device of the present invention also allows the winding of one or more, especially of 1 to 12, multi-filament yams at the same time in order to improve the efficiency of the spinning process. It is in the understanding of the present invention that one or more yam packages on the winder shaft may be heated simultaneously by one or more infrared radiation heaters.
[0033] According to another preferred embodiment of the present invention at least the winder shaft, the yam package the infrared radiant heater and the means for measuring the temperature are encaged in a casing wherein the interior of said casing is optionally heatable. Said casing 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 provides a sound insulation. 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 multilayer 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.
[0034] According to the present invention the size of the casing is preferably dimensioned in such a way that the winding device is either completely encaged or at least the winder shaft, the yam package with its maximum final diameter and the infrared radiant heater are encaged.
[0035] It is also preferably that the additional means for measuring the temperature, winding equipment, preferably a contact roll for controlling the winding speed and preferably a traversing device are also encaged. The minimum dimensions of the casing guarantee a fault-free winding process of a high quality yam. 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 yam packages in a simple manner as well as the production of yam packages having a high weight, preferably of more than 2 kg.
[0036] For the insertion of the multi-filament yams before the start of the winding procedure the casing 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 yam 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 yams transversally to the moving direction of the yam. 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.
[0037] According to one especially preferred embodiment of the present invention the device for the winding of one or more multi-filament yams comprises a contact-roll for controlling the winding speed. Thereby it is possible to measure and control the winding speed and to heat-treat the yam package at the same time. When a casing is used as previously described the contact roll can be placed inside or outside said casing.
[0038] The device for the winding of one or more multi-filament yarns 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 traversing device known in the art may be used as long as the objects of the present invention are achieved.
[0039] The position of the traversing device is not restricted by the present invention. When a casing is used it may be located outside said casing, preferably right in top of the opening for inserting the multi-filament yams 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 winder shaft 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 yams.
[0040] To take-off the yam 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 yam 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.
[0041] In Fig. 1 there is shown schematically a preferred embodiment of the device according to present invention. The device comprises the winder (W) for winding one or more multi-filament yams. At the rear there is provided a driving unit (1) to drive the winder shaft (4) and optionally a contact roll, not shown in the figure. Beneath the winder shaft (4) the infrared radiation unit (6) is situated, consisting of two infrared heating tubes (9) which are arranged in a defined distance parallel to the winder shaft (4). The infrared tubes are fixed in frame (8), mounted on a pivot (7) to allow to adjust the optimum radiation angle and distance to the surface of the winding packages (5). An infrared sensor (10) to detect the temperature at the surface of the winding packages is placed in a sufficient distance to the winder shaft (4) - in this case opposite to the infrared radiator tubes (9). Sensor (10) and radiator tubes (9) are connected to an electronical measurement and control system (11), to keep the selected temperature during winding at the surface of the winding packages (5) constant. The moving direction (A) of the multi-filament yams (3) is indicated by an arrow. In the moving direction of the multi-filament yarns (3) there is arranged a traversing device (2) in front of the winder shaft. The traversing device (2) is interconnected with and driven by the driving unit (1).
[0042] In Fig. 2 another embodiment of the invention is shown. In this embodiment, the device as shown in Fig. 1 comprises an additional casing (12) which encages the winder shaft (4), the yam packages (5), the heater (9), the temperature sensor (10) and the traversing device (2). In the shown embodiment the casing (12) has the form of a casing with a bottom wall (15), a top wall (16), two side walls (17, 18), a front wall (19) and a rear wall (20), the top wall (16) facing the incoming multi-filament yams. The front wall (19) has the function of a door, i. e. the casing (12) may be opened or closed by the front wall (19). At the rear wall (20) outside the casing (12) there is provided a driving unit (1). An opening (13) is provided in the top wall having the form of a slit which extends from the front wall (19) towards the rear wall (20) and which is parallel to the side walls (17, 18). Said opening (13) is partially covered by a flap (14) comprising recesses (21) allowing the multi-filament yams (3) to enter the casing (12) via the opening (13). Since the opening extends to the front wall (19) multi-filament yams (3) may be inserted from the front of the casing (12) when the front wall (19) and the flap (14) are opened.
[0043] In the following the functioning of the afore-described device according to the invention will be described. First of all, the multi-filament yams (3) have to be strung, preferably by air suction gun, to the yam carrying tubes (not shown) fastened on the winding shaft (4) to form the yam packages. After the fixation of the yams the yam carrying tubes fastened on the winding shaft (4) and the traversing unit (2) are driven by the driving unit (1) so that the yam packages (5) are produced.
[0044] When a casing is used as shown in Fig. 2, the multi-filament yams (3) have also to be strung, preferably by air suction gun, to the yam carrying tubes (not shown) fastened on the winding shaft (4) to form the yam packages. For this reason the front wall (19) and the flap (14) have to be opened, so that the multi-filament yams (3) can be inserted in the slit-like opening (13). After the insertion of the multi-filament yams (3) in the opening (13) and the traversing unit (2) and after their fixation on the yam carrying tubes (not shown) on the winder shaft (4), the front wall (19) and the flap (14) can be closed again so that each multi-filament yam runs through its separate recess (21) of the flap, the recesses (21) each having a width corresponding with the width of the one single multi-filament yam (3). Afterwards the yam carrying tubes fastened on the winder shaft and the traversing unit (2) are driven by the driving unit (1) so that the yam packages (5) are produced.
[0045] During the winding of the multi-filament yams (3) the yam packages surfaces are heated by the infrared radiation tubes (9), thereby providing a preselected temperature on the surface of yam packages (5) measured by the infrared sensor (10) and controlled by the electronical measurement and control system (11).
[0046] 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 terephthalate, PBT and/or PTMT, and/or polyamides, such as nylon-6 and/or nylon 6,6. However the device for winding of multi-filament yams according to the present invention is preferably used 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).
[0047] 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.
[0048] The PTMT and/or PBT used in the process of the present invention comprises an infrared absorbing pigment and/or a catalyst having infrared absorbing properties, wherein said pigment and/or catalyst enhances the infrared absorption properties of the yam. The inventive process also comprises the heat treatment of said PTMT and/or PBT multi-filament yams by the use of infrared radiation during winding to yam packages.
[0049] The obtained yam packages show long-term stability during storage and they are insensitive against elevated temperatures during storage and transport. In result, stable and defect-free packages are obtained which are a basic prerequisite for defect-free unwinding of the yarn and for an ideally defect-free further processing.
[0050] The heater is arranged in a defined distance of the winder shaft thereby irradiating a yam package onto said winder shaft. The yam package might be irradiated directly and/or indirectly. In the understanding of the present invention one or more yam packages on the winder shaft may be heated simultaneously by one or more infrared radiation heaters.
[0051] The type of infrared heater is not limited in any way. All usual types of infrared radiant heaters can be used. The heaters comprise e.g. electric elements, gas-fired elements and ceramic elements with different geometries and power stages as well as infrared lamps, such as Nernst-lamps, infrared tubes, infrared lasers and infrared diodes.
[0052] In a preferred embodiment, the heating is carried out with an infra-read heating tube which is located in a defined distance parallel to the winder shaft. Said tube is going parallel to at least that part of the winder shaft where a yam package (5) is placed. Thereby the whole surface of the yam package is irradiated during the winding process.
[0053] By intruducing an infrared absorbing pigment and/or a catalyst having infrared absorbing properties into PBT or PTMT the infrared absorbing properties of the polyester/the yam are enhanced. The process of heat treatment of the multi-filament yam by infrared radiation can be carried out at mild conditions since the improved absorbing properties of the yam allow a warming up of the yam in a very efficient way with a reduced amount of radiation energy. Furthermore, the good absorbing properties of the yam allow a very uniform warming up. In result, the heat treatment can be carried out at a relative low temperature of ≥ 35°C to 65°C and preferably 40 - 50 °C.
[0054] Surprisingly, it was found that a low treating temperature of ≥ 35°C is sufficient for obtaining improved yam properties when an infrared absorbing pigment and/or a catalyst with infrared absorbing properties is introduced into the yam. The properties of yams produced by the inventive method, e.g. the boil-off shrinkage, are equal to or better than those obtained with conventional heating methods using higher temperatures, e.g. by air in a casing surrounding the winder.
[0055] By adding 0,5-3000 ppm and preferably 1-10 ppm of an infra red absorbing pigment to the polyester the irradiation energy can be reduced by 10-50%. The yarn temperature during irradiation can be reduced down to 35°C, preferably 40-50°C. The irradiation energy and the yam temperature can be reduced similarly by adding 0,1-100 ppm and preferably 1-80 ppm of an infra red absorbing catalyst to the polyester.
[0056] Under these conditions, the boil-off shrinkage of the heat treated yams can be kept in the range of < 10%.
[0058] The toughness value differences between yams directly after winding and yams treated in the heating chamber (60°C/ 20 h) are in the range of 2-3. In comparison, the toughness value differences for yams without infra-red absorbing pigment or catalysts which are adsorbed on activated carbon are in the range of 4-6.
[0059] Electronic parts of modem winding machines are sensitive against high temperatures. In continuous operation, electronic modules which are positioned around the winder shaft can be charged with a temperature of 50 °C in maximum. This problem is overcome by the very efficient heating method of the present invention allowing a reduced radiation energy and a low temperature of ≥35°C.The low radiation energies and temperatures of the inventive method allow a minimized heat conduction from the yam to temperature sensitive electronic parts of the winding machine.
[0060] The advantage of the infrared radiation on the surface filaments during winding of the package to stabilize the POY packages at lower temperatures as emphasized above are reached by adding an infrared absorbing pigment or a catalyst with infrared absorbing properties to the polyester. It is also suitable to add a mixture of both.
[0061] Suitable infrared absorbing pigments are selected from the group comprising black or deep shades of dyestuffs, black or deep shades of pigments, carbon black and/or activated carbon. Preferably activated carbon with a specific surface of ≥ 100 m2/g and a mean particle diameter of ≤ 2 µm is used. Still more preferably the activated carbon has an average particle size of ≤ 0,5 µm and a specific surface of ≥ 500 m2/g. Said infrared absorbing pigments are added in a concentration of at least 0,1 ppm, more preferably in 0,5 - 3000 ppm and still more preferably in a concentration of 1 - 10 ppm related to the polyester. It is also possible to add a mixture of two or more infrared absorbing pigments.
[0062] A preferred pigment with infrared absorbing properties for use in the present invention is U1™-pigment, an infrared absorbing additive produced by Zimmer AG, Germany, in a concentration of 0,1-10 ppm according to patent DE 10121542.
[0063] Also catalysts which can increase the infrared adsorption of the polymer are used in the inventive method. Suitable catalysts with infrared absorbing properties are selected from metal compounds of Ti, Zr, Sb, Ge, Sn and/or Al wherein the metal is present in the ionic form. Examples of suitable compounds are tetrabutyl titanium, tetrapropyl titanium, TiO2, Sb2O3, antimony acetate, GeO2, tetrabutyl tin, dibutyl-tin-diacetate, tetraisopropyl tin and SnO2. Preferably, a titanium compound is used and most preferably TiO2.
[0064] Said metal compounds/catalysts are added an amount of 0,1-100 ppm of the metal related to the polyester, preferably in a concentration of 1 - 80 ppm of metal and still more preferably 1 - 20 ppm which is highly suitable according to the present invention.
[0065] These catalysts might be used in pure form or fixed or adsorbed onto a carrier selected from the group comprising activated carbon, silica and crosslinked polymers. In a preferred embodiment the catalyst is adsorbed on activated carbon having an average particle size of less than 2 µm and a specific surface of at least 100 m2/g and more preferably less than 0,5 µm and at least 500 m2/g.
[0066] Preferably the mass ratio of said catalysts to activated carbon is 1 : 50 - 50 : 1. When a titanium compound selected from tetrabutyl titanium, tetrapropyl titanium and TiO2 is used, the concentration of titanium is preferably 1 - 80 ppm related to the polyester and the mass ratio of activated carbon to titanium is 1 : 50 - 50 : 1 and preferably 1 : 2 - 20 : 1.
[0067] Another preferred catalyst with infrared absorbing properties for use in the present invention is Ecocat B™ from Zimmer AG (Chemical fibers International Vol. 52, 392-394, Dec. 2002) consisting of Ti, adsorbed in a heterogeneous phase of a carrier made from fine-grain, porous particles with a large inner surface. In a preferred embodiment of the present invention, a PTMT is used which is produced with Ecocat B™ in a concentration of 5-100 ppm of Ti related to the polyester. Ecocat B™ is optionally mixed with other suitable catalysts as Antimony(III)acetate or -oxide or titaniumorthobutylate for polycondensation.
[0068] A system using a metal compound as catalyst and a carbon containing co-catalyst is claimed in DE 10121542. Surprisingly this catalyst system is also effective in esterification and polycondensation of PTMT. Using this catalyst system a particular infrared active PTMT POY can be produced.
[0069] 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.
[0070] 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.
[0071] PTMT or PBT containing special additives to increase the spinning speed as described in DE 10054422 [PTT-MOD5] can also be used.
[0072] 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 an intrinsic viscosity in the range from 0.70 dl/g to 1.0 dl/g are thereby particularly advantageous.
[0073] 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 a typical 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. Fourné (1995), published by Hanser-Verlag, Munich (in German), for the specific details of said process.
[0074] In the process in accordance with the invention, 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.
[0075] 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.
[0076] 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.
[0077] 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.
[0079] The filaments are bundeled in an oiler pin which supplies the yam with the desired amount of spin finish at a uniform rate.
[0080] According to the invention, the multi-filament yams are preferably entangled before being wound up.
[0081] The bundled yams are drawn off by the use of a first godet system and guided to the winder. Further godet systems can be employed before the yarns are wound up in the winder assembly to form packages on tubes. The optional further godet systems are included for drawing, thermosetting and relaxation of the yams.
[0082] According to the present invention the polyester multi-filament yams can be optionally 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.
[0083] According to one especially preferred embodiment of the present invention the polyester filaments are heat-treated by the use of heated godets.
[0084] According to another preferred embodiment, the temperature on the surface of the yam package is detected and controlled by a means for measuring and controlling the temperature. Preferably such means comprises at least one sensor connected with an electronical measurement and control system and the infrared radiant heater to control the temperature at the package surface during winding. Usually, the temperature is held constant. The type of sensor is not limited to a special type. Preferred are usual thermal-optical sensors or infrared sensors.
[0085] Optionally, the yam package is heat treated inside a casing encaging at least the infrared radiant heater, the winder shaft, the sensor for detecting the temperature and the yam package. Such casing was already described in detail in connection with the device of the present invention. According to the present invention it is preferable to measure the temperature inside the casing and to adjust the temperature in the range of ≥ 35°C to 65°C and preferably 40-50°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 winder shaft in view of the moving direction of the yam, 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 infrared radiation energy.
[0086] The shape of the package is preferably controlled by the use of a traversing device which is arranged before said winder shaft in view of the moving direction of the yarn. When a casing is used as previously described, the traversing device may be located either outside or inside said casing. However, it is especially advantageous to control the shape of the package by the use of a traversing device located inside the casing which is arranged before the winder shaft 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.
[0087] The process of the present invention allows the manufacture of yam packages having a cheese-like shape, as schematically shown in Fig. 3. A shrinkage 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 winder shaft any longer, as well as the formation of bulges with hard edges, as schematically shown in Fig. 4, 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 cheese-like shape even during storage for a longer period of time, for example for 15 weeks at least.
[0088] To set the winding tension according to the invention, the winding speed of the POY is adapted. It is preferable to select a winding speed up to ±2% different to the take-up speed of the last godet system. The winding 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 2,900 to 6,000 m/min.
[0089] 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.
[0090] 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.
[0091] 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. The concentration of the solution amounts to 0.5 g polyester to 100 ml of solution.
[0092] 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.
[0093] 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 (C7H16) 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 Da and the density of the crystalline polyester Dk are taken as the basis. The corresponding computation is known from the literature; for example, the following is valid for PTMT: Da = 1.295 g/cm3 and Dk = 1.429 g/cm3.
[0094] 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).
[0095] 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.
[0096] 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.
[0097] 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.
[0099] The yam toughness is negatively influenced by thermal treatment, especially of a PTMT or PBT yam. A low difference of the yam toughness after winding in comparison with the yam toughness after treatment of the yam in a heating chamber is a quality criteria of the yam.
[0100] 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
[0101] Corterra-type crystalline PTMT chips (Shell Oil Company (USA)) with an intrinsic viscosity of 0.93 dl/g, a crystallization temperature of 71°C, and a glass transition temperature of 46°C, were dried in a toumble dryer at a temperature of 130°C to a water content of 12 ppm. The chips were melted in a 3E4 extruder from the firm Barmag, so that the temperature of the melt amounted to 260°C. The melt was then conveyed to the spinning pump through a product line and fed to a spin pack wherein the melt throughput to the spin pack was controlled to 32.0 g/min. The melt was extruded through a nozzle plate 80 mm in diameter, with 34 holes 0.25 mm in diameter and a length of 0.75 mm. The spin pack pressure amounted to approximately 120 bar.
[0102] 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.
[0103] Thereafter the bundled multi-filament yam was drawn-off by the use of a godet system consisting of a non-heated S-wrapped pair of non-heated godets. The take-up speed at the first godet amounted to 3,100 m/min and the take-up speed at the second godet amounted to 3,116 m/min.
[0104] Finally, the multi-filament yam was wound on a type SW6 winder (BARMAG (Germany)) at a winding speed of 3,150 m/min while being heated by 5 infrared radiation tubes, 1000 W each (Phillips). The distance of the radiation tubes to the winder shaft was 275 mm. The temperature at the surface of the package of 45 °C was measured with an infrared sensor type CI (Raytek), having a distance of 220 mm to the winder shaft. The room climate was set at 24°C at 60% relative humidity.
[0105] By the present method cheese-like yarn packages of 14 kg have been 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 packages. Another part of the packages was stored in a storing room for 15 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 102 dtex have been stretch-textured in an additional step with a speed of 600 m/min. The final DTY had a tensile strength of 23 cN/tex and an elongation at break of 35%.
Table 1:
| Materials characteristics of the Example 1 | |||
| Characteristics | Directly after the winding | After treatment in a heating chamber | After 15 weeks |
| Tensile strength [cN/tex] | 23.8 | 22.5 | 22.2 |
| Elongation at break [%] | 84.6 | 81.1 | 80.3 |
| CV-elongation at break* [%] | 2.9 | 2.4 | 3.0 |
| Uster-half inert [%] | 0.43 | 0.39 | 0.45 |
| Uster-normal [%] | 1.09 | 0.75 | 0.86 |
| Boil-off shrinkage [%] | 2.9 | 2.6 | 1.9 |
| *: coefficient of variation of the elongation at break |
Comparative Example
[0106] Example 1 was repeated except that the take-up speed at the first godet and the second godet amounted to 3,100 m/min and 3,119 m/min, respectively. Finally the multi-filament yarn was wound at a winding speed of 3,155 m/min without infrared radiation.
[0107] After the winding of about 4 kg a significant shrinkage of the yam package as well as the formation of bulges were observed, so that the winding process had to be stopped to avoid damaging of the winder shaft. The observed material characteristics are summarized in table 2.
Table 2:
| Materials characteristics of the Comparative Example | |
| Characteristics | directly after the winding |
| Tensile strength [cN/tex] | 23.7 |
| Elongation at break [%] | 84.3 |
| CV-elongation at break*[%] | 5.3 |
| Uster-half inert [%] | 0.46 |
| Uster-normal [%] | 1.13 |
| Boil-off shrinkage [%] | 59.7 |
| *: coefficient of variation of the elongation at break |
Example 2, 3 and 4
[0108] Example 1 was repeated except that the melt throughput was changed to 107 g/min and the speed of the first goded was set to 4,000 m/min, the speed of the second godet wa set to 4,017 m/min and the winding speed was changed to 4,060 m/min. Similarly to Example 1, in Example 2, the multi-filament yam was wound on a type SW6 winder (BARMAG (Germany)); wherein the yam package was infrared radiaded and the surface temperature of the package was 60°C controlled by sensor.
[0110] The conditions of example 3 were repeated in example 4, except that the Corterra-Polymer meltwas mixed with 5 ppm of 'U1' pigment, an infrared absorbing additive produced by Zimmer AG, Germany, before spinning, and the surface temperature of the package was set to 40°C.
The room climate in all three examples was 24°C at 60% relative humidity.
[0111] By the present method cheese-like yarn packages have been obtained, which could be taken off the winder shaft 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. A comparison of the shape of the packages and of the yams characteristics of a 15-week stored package (see Table 4) revealed that the present multi-filament yams exhibited a high storage stability without significant worsening of the material characteristics.
Table 3:
| Treatment and materials characteristics of the Example 2-4 | ||||||
| Sample | 2 | 3 | 4 | |||
| Infrared absorbing compound | none | none | 5 ppm | |||
| Surface temperature of the package [°C] | 60 | 45 | 40 | |||
| Characteristics | directly after the winding | after treatment in a heating chamber | directly after the winding | after treatment in a heating chamber | directly after the winding | after treatment in a heating chamber |
| Titer [dtex] | 265 | 266 | 261 | |||
| Tensile strength [cN/tex] | 28.0 | 27.6 | 28.1 | 27.8 | 26.9 | 26.7 |
| Elongation at break [%] | 60.7 | 60.1 | 61.6 | 61.3 | 64.9 | 64.7 |
| CV-elongation at break* [%] | 3.9 | 3.2 | 5.9 | 4.9 | 4.3 | 4.4 |
| Uster-half inert [%] | 0.77 | 0.82 | 0.68 | 0.70 | 0.72 | 0.82 |
| Uster-normal [%] | 1.02 | 1.09 | 1.08 | 1.00 | 1.11 | 1.0 |
| Boil-off shrinkage [%] | 4.6 | 4,4 | 7.8 | 6,2 | 5,5 | 5,3 |
| Toughness value | 218 | 214 | 221 | 214 | 217 | 215 |
| Toughness value difference | 4 | 6 | 2 | |||
| *: coefficient of variation of the elongation at break |
Table 4:
| Materials characteristics of the Example 3 | |||
| Characteristics | directly after the winding | after treatment in a heating chamber (20 h/ 60°C) | after 15 weeks stored (20-40°C) |
| Titer {dtex] | 266 | ||
| Tensile strength [cN/tex] | 28.1 | 27.8 | 27.9 |
| Elongation at break [%] | 61.6 | 61.3 | 62.1 |
| CV-elongation at break*[%] | 5.9 | 4.9 | 3.6 |
| Uster-half inert [%] | 0.68 | 0.70 | 0.70 |
| Uster-normal [%] | 1.08 | 1.00 | 0.96 |
| Boil-off shrinkage [%] | 7.8 | 6,2 | 6.4 |
| Toughness value | 221 | 218 | 220 |
| Toughness value difference | 3 | ||
| *: coefficient of variation of the elongation at break |
Example 5 and 6
[0112] PMTP chips were produced in Zimmer's pilot plant. In this batchwise production of PTMT a part of prepolymer from a preceding, prepolymer batch in a quantity of about 42 wt% of the nominal batch is kept back in the esterification reactor for the next reaction cycle for stirring the esterification product and for feeding and heating the raw materials trimethylenglycol (TMG) and terephthalic acid (TPA) as a paste including the esterification catalyst in a concentration of 15 ppm Ti selected from Ecocat B™ (Zimmer AG) as 10 wt.-% solution in TMG and 20 ppm Co from cobalt acetate as color agent. Ecocat B ist an infrared active catalyst from Zimmer AG (Chemical fibers International Vol. 52, 392-394, Dec. 2002) consisting of Ti, adsorbed in a heterogeneous phase of a carrier made from fine-grain, porous particles with a large inner surface. The molar TMG to TPA feed ratio was 1.3 : 1.
[0113] The quantity of TPA fed into the esterification reactor is 180 kg. The feeding time is 130 minutes. The total cycle time of esterification in examples 5 and 6 is 160 minutes at a temperature of 260°C and a pressure of 1500 mbar (abs.). A column disposed subsequent to the esterification reactor is used for separating the low-boiling compounds, mainly process water, from the trimethylene glycol in the vapors from the esterification, and for the recirculation of the distilled TMG to the process all the time of esterification.
At 5 minutes before starting the vacuum program of the prepolycondensation 65 ppm titanium are added to the esterification product as polycondensation catalyst via the catalyst liquid of 2 wt-% tetrabutyl -o-titanate and 1 wt.-% glacial acetic acid in TMG, at steady stirring of the product mixture. The precondensation is carried out in 30 minutes at a simultaneous pressure reduction to 50 mbar (abs.). and a temperature of 260 °C. Thereafter, the prepolymer melt is transferred to a disc ring reactor, and the polycondensation is started by agitating defined by a standard program of speed control and further reducing the pressure within 45 minutes to 0.5 mbar as final pressure. The polycondensation temperature in examples 5 and 6 increased from 260 to 266°C. The total duration of polycondensation 160 min. Upon reaching the viscosity maximum of 0.925 dl/g the polycondensation is stopped. At an applied pressure of 55 to 60 bar the polymer melt is discharged from the reactor and granulated.
[0114] Different from example 5, in example 6 after finishing of the esterification 0.33 wt-% of TiO2 (related to polymer), Type LWSU (Sachtleben) as 20 wt.-% suspension in TMG was added to the reactor while stirring. After 10 minutes the catalyst as described in example 5 was added and furtheron the PTMT process completed.
[0115] The chips of example 5 and 6 were dried and spun under the same conditions as used in example 1.
[0116] The spin process conditions and the material characteristics are shown in table 5.
For comparison the characteristics of Example 1 are also shown.
[0117] As demonstrated, the PTMT produced with Ecocat B shows comparable spinning behaviour to the commercial PTMT Corterra made by Shell. By the integrated infrared absorbing compounds the treatment temperature to produce stable POY packages can be significantly decreased.
Table 5
| Process conditions and materials characteristics of Examples 1,5,6 | |||
| Sample | 1 | 5 | 6 |
| TiO2 content [wt.-%] | 0,33 | none | 0,33 |
| Infrared absorbing compound [ppm] | 0.0 | 3 | 3 |
| Amount delivery [g/min] | 32 | 31,9 | 32 |
| Titer [dtex] | 102 | 102 | 102 |
| Take-up speed at the first godet [m/min] | 3,100 | 3,100 | 3,100 |
| Take-up speed at the second godet [m/min] | 3,116 | 3,119 | 3,119 |
| Winding speed [m/min] | 3,150 | 3,155 | 3,150 |
| Surface temperature of the package [°C] | 60 | 40 | 50 |
| Tensile strength [cN/tex] | 23.8 | 22,6 | 22,6 |
| Elongation at break [%] | 84.6 | 77,2 | 78,7 |
| CV-elongation at break* [%] | 2.9 | 5,3 | 4,7 |
| Uster-half inert [%] | 0.43 | 0,40 | 0,56 |
| Uster-normal [%] | 1.09 | 1,11 | 1,10 |
| Boil-off shrinkage [%] | 2.9 | 5,9 | 2,9 |
| *: coefficient of variation of the elongation at break |
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 polyester yam comprises an infrared absorbing pigment and/or a catalyst having
infrared absorbing properties, wherein said pigment and/or catalyst enhances the infrared
absorption properties of the yam, and that the yam is heat-treated by the use of infrared
radiation during winding to a yam package.
2. A process according to claim 1 characterized in that the multi-filament yam is heat-treated by the use of infrared radiation at a temperature
in the range of ≥ 35°C to 65°C.
3. A process according to claim 1 or 2 characterized in that the heat treating is carried out with at least one infrared radiant heater which
irradiates a yam package on said winder shaft.
4. A process according to claim 3 characterized in that the infrared radiant heater comprises an infrared heating tube which is arranged
parallel to the winder shaft.
5. A process according to any of the preceding claims characterized in that the infrared absorbing pigment is selected from the group comprising black or dark
shades of dyestuffs, black or deep shades of pigments, activated carbon and/or carbon
black.
6. A process according to claim 5, characterized in that the infra red absorbing pigment is activated carbon having an average particle size
of less than 2 µm and a specific surface of at least 100 m2/g.
7. A process according to any of the preceding claims characterized in that the polymer contains an infrared absorbing pigment in a concentration of 0,5 - 3000
ppm related to the polyester.
8. A process according to claim 1-4, characterized in that the catalyst with infrared absorbing properties is selected from componds of Ti,
Zr, Sb, Ge, Sn and/or Al wherein the metal is present in the ionic form.
9. A process according to claim 8, characterized in that the catalyst with infrared absorbing properties is selected from the group comprising
tetrabutyl titanium, tetrapropyl titanium, TiO2, Sb2O3, antimony acetate, GeO2, tetrabutyl tin, dibutyl-tin-diacetate, tetraisopropyl tin and/or SnO2.
10. A process according to claim 8 or 9, characterized in that the polyester contains the catalyst with infra red absorbing properties in a concentration
of 0,1 - 100 ppm of the metal related to the polyester.
11. A process according to claim 8 or 9, characterized in that the polyester contains the catalyst with infra red absorbing properties in a concentration
of 1-80 ppm of the metal related to the polyester.
12. A process according to claim 8-11, characterized in that the polyester comprises the catalyst and activated carbon.
13. A process according to claim 12, characterized in that the catalyst is adsorbed on activated carbon having an average particle size of less
than 2 µm and a specific surface of at least 100 m2/g.
14. A process according to claim 12 or 13 characterized in that the mass ratio of catalyst to activated carbon is 1 : 50 - 50 : 1.
15. A process according to any of the preceding claims characterized in that the temperature on the surface of the yarn package is detected by at least one sensor
connected with an electronical measurement and control system and the infrared radiant
heater in order to control the temperature at the package surface during winding.
16. A process according to any of the preceding claims characterized in that the the yam package is heat treated inside a casing encaging at least the infrared
radiant heater, the winder shaft, the yam package and the sensor for detecting the
temperature.
17. A process according to any of the preceding claims characterized in that said yam-package has a cheese-like shape.
18. A process according to any of the preceding claims 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.
19. A process according to claim 18 characterized in that said at least one polyester multi-filament yarn is heat-treated by the use of heated
godets.
20. A process according to any of the preceding claims characterized in that the winding speed is adjusted to between 2,500 m/min and 6,000 m/min.
21. A 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, obtainable
by a process according to claim 1-19, 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 %.
22. A device for the winding of one or more multi-filament yams comprising a commercial
winder (W) characterized in that at least one infrared radiant heater (9) is arranged in a defined distance from the
winder shaft (4) thereby irradiating a yam package (5) which is placed on said winder
shaft (4).
23. A device for the winding of one or more multi-filament yams according to claim 22
characterized in that the infrared radiant heater comprises an infrared heating tube arranged parallel
to the winder shaft (4).
24. A device for the winding of one or more multi-filament yams according to claim 23,
characterized in that said infrared heating tube (9) is fixed in a frame (8) and mounted on a pivot (7).
25. A device for the winding of one or more multi-filament yams according to claim 22-24
characterized in that the distance between the package surface of the maximum yam load package and the
infrared radiant heater is at least 25 mm.
26. A device for the winding of one or more multi-filament yams according to claims 22-25
comprising at least one sensor connected with an electronical measurement and control
system and the infrared radiant heater.
27. A device for the winding of one or more multi-filament yams according to claims 22-26
characterized in that at least the winder shaft (4), the yam package (5), the infrared radiant heater (9)
and the sensor for measuring the temperature (10) are encaged in a casing (12) wherein
the interior of said casing is heatable.