EP1185728A1

EP1185728A1 - Method for producing ultra-fine synthetic yarns

Info

Publication number: EP1185728A1
Application number: EP00927131A
Authority: EP
Inventors: Andreas Mueller; Reinhard Wagner; Dietmar Wandel; Heinz Schuettrichkeit
Original assignee: ZiAG Plant Engineering GmbH
Current assignee: Roehm GmbH Darmstadt; LL Plant Engineering AG
Priority date: 1999-05-14
Filing date: 2000-05-02
Publication date: 2002-03-13
Anticipated expiration: 2020-05-02
Also published as: DE50004736D1; ATE256206T1; EP1185728B1; WO2000070132A1; DE19922240A1; US6420025B1

Abstract

The invention relates to a method for producing a synthetic, ultra-fine, polyester or polyamide-based continuous yarn in the range of 0.25 to 0.9 denier per POY filament, by melt-spinning at winding-off speeds of between 2 000 and 6 000 m/min, with a high level of spinning stability. 0.05 to 5 wt. % of a second, immiscible, amorphous polymer can be added to the polyester or polyamide. The invention is characterized by the regulation of a balanced temperature profile in the cross-section of the filament band before it reaches the drafting zone and by the appropriate coordination of the retreat and the drafting point of the filaments in the blow shaft.

Description

Process for the production of ultra-fine synthetic yarns

Description:

The present invention relates to a method for producing a synthetic ultra-fine continuous yarn based on polyester or polyamide in the range 0.25 to 0.9 denier per POY filament by melt spinning at take-off speeds between 2000 and 6000 m / min. A second immiscible amorphous polymer may be added to the polyester or polyamide in an amount of 0.05 to 5 percent by weight.

Several authors have dealt with the problems in the production of fine and ultra-fine filaments:

In "Advanced Fiber Spinning Technology" (Oodhead Publishing Ltd, 1994, p. 191), Nakajima describes a process for spinning ultra-fine fibers, the filaments being blown with a radially directed cold air stream in addition to the normal crossflow blowing immediately after the spinning. Tekaat (publication at the international man-made fiber conference in Dornbirn 1992, p. 8) describes investigations in the manufacture of microfilament yarns. It was found that the blown air has difficulty penetrating the bundle of threads at high numbers of filaments and that the filaments cool in the middle significantly later than the filaments near the edges.

According to Ziabicki ("Fundamentals of Fiber Formation", J. Wiley & Sons, 1976, p. 196ff and p. 241), the cooling conditions immediately below the nozzle package are decisive for the thread quality. In addition, the bundle of threads presents a considerable resistance to the flow, which can lead to the blown air flowing around the bundle instead of flowing through it.

Some patents suggest additional heating of the filaments with heating gas or with radiation heating for the production of microfibers:

US Pat. No. 5,310,514 (Corovin) claims a process for the production of microfilaments, in which a hot air stream for protection of the freshly spun filaments flows out parallel to them from an annular slot in the nozzle package. The temperature of the hot air is ± 10 K of the melt temperature. The technical implementation is complex and the constancy of the air flow necessary in this critical area is difficult to guarantee.

EP0455897 A (Karl Fischer) describes a method for heating the individual filaments via a channel system within the nozzle plate through which hot air is passed. The aim is to improve the warping of the filaments. Compensation for the heat losses of the filaments close to the edge is therefore not possible. The hot gas flows individually around the filaments. The thread distortion is to be supported in this way. The temperatures can be in the range of the melt temperature or above.

GB patent 1391471 (Hoechst) describes a heater for technical yarns. This means that a low pre-oriented yarn can be produced with increased throughput. The device consists of two conical half-shells, the lower one is heated and the upper polished shell reflects a large part of the heat radiation onto the filaments. It is expressly pointed out that only a little radiation should hit the nozzle plate. The temperature curve along the heating section is highly parabolic with a maximum of approximately half the length (approx. 120 K above the melt temperature).

US Patent 5661880 (Barmag) claims radiant heating of the filaments emerging from the spinneret. A process for spinning with a conical heating section is described. The temperatures on the heating surface are preferably 450 - 700 ° C, well above the melt temperature. In addition, heating of the nozzle plate is claimed by heating tapes running in or on it. The contact time available for heat transfer to the melt is thus reduced to a few seconds. There is no differentiation between different heating of the internal and external melt flows. This is to prevent the melt from being oriented too early in the nozzle capillaries. Moreover deposits on the nozzle are to be reduced and the throughput can be increased.

US Patent 5182068 (ICI) describes a process which is said to reduce necking on draws above 5000 m / min. It is said that a heated return with a temperature profile that is constant over the run length (300 °) only causes the neck point to shift, while a return with progressively decreasing temperature profile (300 -> 200 ° C) brings about a clear defusing of the neck point. The thread speed before the necking is increased and the neck-draw ratio before / after the necking is reduced. Speeds above 7000 m / min are required.

GB patent 903427 (Inventa) claims a spinning tube with a length of at least. In the upper region there is a temperature of 10 - 80 K below the melt temperature. The temperature in the lower pipe section is less than 100 ° C. The heating can take place either directly or via a heat transfer medium.

US Patent 5250245 (DuPont) describes a spin orientation process for the production of fine polyester filaments with improved mechanical properties and titre uniformity. This is achieved by choosing a suitable polymer viscosity and appropriately adapted spinning conditions.

US Pat. No. 4,436,688 (Zimmer) claims a process with draws between 600 and 6000 m / min in which the spun filaments undergo a return. Its length depends on the take-off speed and the filter surface load.

US Patent 5866050 (DuPont) discloses heating the

Spin pack so that the filaments with almost the same

Exit the temperature from the nozzle bores.

The procedure does not take into account the different

Cooling behavior of the middle and outer filaments, especially with very fine and high-capillary ones

Titers.

Different methods are proposed in the cited documents for heat management of the filaments immediately after extrusion. Some of these methods have the disadvantage that they impair the formation of a rest zone in the immediate area after the thread extrusion by the supply of a heating gas. However, this quiet zone is absolutely necessary to achieve high yarn uniformity.

Many of the above-mentioned methods use the radial or one-sided supply of heat to the filaments, which leads to the fact that in particular the outer filaments are subject to a stress relief which increases the uneven running and thus reduces the uniformity of the yarn.

The different cooling behavior between inner and outer filaments is decisive for the running stability. The temperature profile of the emerging filaments must therefore be able to be adjusted depending on the polymer throughput. The temperature profile of the filaments that have already emerged so too influence that this cooling behavior is countered has not been considered by the prior art.

So far, it has been problematic to achieve low break rates in the POY. The aim of the invention is to achieve uniformity in ultra-fine yarns (approx. 0.25-0.89 dpf), as is the case with the current process principle in the production of high-count yarns (approx. 1.0-1.2 dpf) can be reached.

The most commonly used blowing systems in practice are based on single-sided blowing to facilitate access. It should be possible to use this principle of one-sided blowing.

This object is achieved according to the invention by a method and a yarn according to the claims.

The solution to this problem is achieved by the complex interaction of several essential process steps. The individual process steps for the production of ultrafine microfibers are described below, from the extrusion of the melt to the winding of the POY yarn.

A polyester, such as polyethylene terephthalate (PET), polypropylene or polybutylene terephthalate or polyamide, such as PA 6 or PA 6.6, or copolymers thereof, is used as the raw material. PET with an intrinsic viscosity between 0.59 and 0.66 dl / g is preferred. Adequate structural homogeneity and sufficient thermal homogeneity of the melt before reaching the spin pack must be ensured. A second immiscible amorphous polymer can be added to the base polymer in an amount of 0.05 to 5 percent by weight. The polymer added is preferably a copolymer which is composed of at least two of the following monomer units:

0 to 95% by weight of A, where A is a monomer of the formula CH ₂ = C (R) -COOR ¹ , where R is -H or -CH ₃ and R ¹ is straight-chain or branched C ¹ -C ¹ -alkyl or cyclohexyl , 0 to 40% by weight B, where B is a monomer consisting of maleic acid or maleic anhydride, and 5 to 85% by weight C, where C is a monomer consisting of styrene or methyl-substituted styrene, and where (% by weight A +% by weight B +% by weight C) = 100.

With the method according to the invention, POY single titer of 0.25-0.9 denier, corresponding to a single end titer of the drawn yarn of 0.15 to 0.52 denier, can be achieved. The elongation at break in the PET-POY is in a range from 100 to 145% and the specific tensile strength is between 18 and 33 cN / tex. Take-off speeds between 2000 and 6000 m / min are used. Some process parameters for polyester (PET) which are characteristic according to the invention are listed in Table 1.

Table 1:

The relationships between the individual parameters can be determined using the following calculation formulas:

(d. t {c _) filter

For example, a round packet according to US Pat. No. 5,304,052 or US Pat. No. 5,755,595 is used as the nozzle packet. The dwell time of the melt within the package is adjusted by means of internals so that it does not exceed 12 minutes and does not fall below 5 minutes. A sequence of different fabric layers with the finest mesh sizes of 5 to 15 µm in combination with or without fine steel sand in the grain size 88 to 250 μm was used as the filtration medium. To ensure a high degree of polymer homogeneity, sufficient shearing or fragmentation of the higher molecular gels present in the melt is necessary, which can be done either by fine steel sand or by appropriate built-in components in the spin pack with the finest pore openings of 50 to 1000 μm. The total package pressure was set so that at least 130 bar was reached with filter surface loads of 0.25 to 0.80 g / min / cm ² .

The use of the fine nozzle bores required for the process proved to be critical. In the case of multi-layer nozzle filters, interference particles within the nozzle filter and especially in the area of the filter surround cannot be reliably excluded. This problem was solved by using fine loose filter layers made of metal mesh with finenesses greater than 4000 mesh / cm ² , preferably with greater than 15000 mesh / cm ² (40 μm mesh size) directly on the nozzle plate. This ensures the necessary piecing security.

The hole density of the nozzle plates used can be set between 1.5 and 6.0 holes / cm ² . The diameter d of the capillary bores in the nozzle plate is selected so that the apparent wall shear rate of the melt within the capillaries is between 5,000 and 25,000 s ^"1 (for PET see Tab. 2). This ensures additional heating of the melt.

Table 2:

The following relationships apply:

, 4 p - d melt Kap = 193Θ —- φ _Ka mrt], 7 ^ = 3510 7 ^ = 690

™ Fil ^' ^ ^{~ η} 2 ^{' lo} ^ ⁾

The capillary diameter is chosen between 0.08 mm and 0.12 mm. The diameter of the individual capillary bores in the nozzle plate does not have to be constant over the cross section of the nozzle plate, but can be adapted in inverse proportion to the temperature gradient measured on the surface of the nozzle plate. The deviation between central and near-edge holes is a maximum of 0.2 d, preferably 0.1 d. In this diameter range, the exit speeds are limited by two effects: First, a sufficiently high spraying speed of at least 7 m / min is necessary to avoid the risk of cohesive breaks. On the other hand, an upper limit of 20 m / min must not be exceeded, since otherwise flow anomalies can occur, which are noticeable in an irregular melt leakage from the capillary bore (corkscrew effect). The length L of the capillaries is chosen so that a sufficiently high melt pressure is achieved with the inevitably low filter surface load in front of the nozzle plate. This means that there are sufficient pressure reserves for an even radial distribution of the melt. The pressure in front of the nozzle plate should be between 50 and 100 bar, preferably between 70 and 100 bar. Depending on the melt throughput per capillary bore, an L / d ratio between 2 and 5 can be selected (see Table 2).

The setting of a balanced temperature profile in the cross-section of the thread bundle before reaching the draft zone was recognized as essential for stabilizing the spinning security. It is known that filaments are drawn out when the glass transition temperature T _g is reached. Filaments that start at different temperatures will reach the temperature suitable for warping (T _SC heat <T <T _g ) with constant cooling conditions even at different distances from the nozzle plate. However, it is clear that the filaments close to the edge will cool faster than the filaments in the center of the thread bundle, since they are in direct contact with the ambient air (see Fig. 2). To set a balanced temperature profile at a certain distance from the nozzle plate, it is therefore not sufficient to apply the same initial temperature to all filaments. Rather, the outer filaments must have a temperature advantage over the central filaments, which must be set so that the temperatures of the near-center and central filaments have equalized shortly before reaching the warping zone.

(T _Ra nd - T _M _tte) measured as the surface temperature difference on the nozzle plate between the center and edge of the nozzle plate in the claimed titer range according to the following relationship about the temperature difference between the spinning beam heating and the polymer,

(T_eh.e__ung -T _Sc t_neize) / depending on the filament throughput m _F _ι, the withdrawal speed Vabzug and the filter area A _F _ιter as follows:

Heating melt edge center

and 4K ≤ (T - T _t ,.) ≤ 13K

Margin center ^J

The direct supply of the required heat via the walls of the nozzle package was surprisingly effective. In addition to the pure heat losses of the nozzle plate, additional heat was introduced into the spin pack to heat the melt near the wall. This requires a correspondingly long dwell time in the nozzle package, which, however, could be set with appropriately shaped package internals due to the low package throughput in the claimed titer range. The heat required to set the desired temperature profile is transferred to the melt partial flow near the wall via metallic heat conduction in the nozzle package.

This partial melt stream near the wall can either be heated to the required excess temperature over the entire length H of the inner wall of the spin pack in contact with the melt or only on a partial section 1 of the inner wall in contact with the melt, in which case the required one

Overtemperature ΔTscmeize pickling is increased according to the area ratio H / 1. This extra heated The surface should then preferably be provided in the lower part of the spin pack at the level of the nozzle plate and finally with the lower edge of the nozzle plate in the form of a heating frame with through openings for the spin packs and with a heating which can be controlled independently of the spinning beam. Separate heating of the spinning beam and the product line is a prerequisite for setting the required temperature difference.

The formation of different temperature filaments in a plane transverse to the direction of the thread has a major influence on the stability of the thread path. Filaments at different temperatures also reach their thread end speed at a different distance from the nozzle plate, so that cross sections result in filaments of different speeds which, due to their differently pronounced suction, cause turbulence within the filament bundle. In principle, three speed ranges can be distinguished when pulling out the yarn using known methods:

1. The area in front of the draft zone: slow thread speed in the range of 7 - 200 m / min, an unbalanced temperature profile has only a minor impact on the absolute amount of the speed differences.

2. The actual draft zone: speed range from 200 - approx. 2500 m / min, with an unbalanced profile, slow (not yet drawn) and fast (already drawn) filaments are present in this (fictitious) cross-section. Filaments near the edge without a temperature increase reach their final speed much earlier than filaments in the center of the Bundle of threads. The result is a restless thread run mainly caused by the suction effect of the faster filaments, which suck the slower filaments. In extreme cases, individual filaments stick together and thread breaks occur. The restless thread run has a clear impact on the yarn uniformity. Existing inequalities are increasing here (see Fig. 2).

3. The area after the delay zone: speed above

2500 m / min, different thread temperatures have hardly any influence on the spinning safety.

The draft zone extends to the solidification point h ₉ s% of the melt, which is defined in such a way that 98% of the thread take-off speed is reached here.

Through our own investigations of the flow field in the vicinity of a bundle of threads flowing crosswise on one side, the disadvantages of the one-sided blowing were confirmed according to the above statements by Ziabicki. The flow field was displayed using a laser light section system from ILA. With this method, the examination area is illuminated in different cutting planes with a powerful, double-pulsed NdYAG laser. An aerosol is applied to the blown air, which reflects the laser pulses in the area of the cutting plane. The visualization is carried out with a high-resolution CCD video camera. The speed and the direction of flow are represented by a vector field. The direction of the vector arrows results from the spatial displacement of the droplets and the velocity of the droplets from the spatial displacement of the droplets and the time interval between two pulses. It has been found that one-sided blowing creates strong inhomogeneities in the thread bundle. These are mainly caused by the Stowage zone in front of the thread bundle and through the swirl area in the lee of the thread bundle (see Fig. 1). These disadvantages are eliminated with the method according to the invention.

For this purpose (see Fig. 3), the distance h to the nozzle plate, on which a balanced temperature profile already exists due to cooling of the filaments near the edge, must be smaller than the distance of the solidification point from the nozzle plate (see Fig. 3). The setting is made by increasing the temperature of the melt heating, for example using laser Doppler anemometry. The thread speeds of near-center and central filaments are measured simultaneously, while the temperature of the melt heating is adjusted so that the speed difference between near-center and central filaments is less than 40% of the pull-off speed of the yarn and preferably less than 15%. The measuring position is located immediately upstream of the drafting zone, which can be represented in the claimed titer range depending on the Filamentdurchsatz m _F n [g / min], the withdrawal speed from ug _z [m / min] and the draft ratio W as:

9000 9000 hg _™ , = 38 fil where (Fil + 6.0) [mmj v • W v • W

Deduction deduction

Excessive cooling of the outer filaments must be prevented. It is precisely in this titer range that the filaments cool down particularly quickly due to the large specific surface area. The relative surface area of a filament, calculated according to the following relationship: wobeid = 1 J9. ^p IM \ Melt

melt

gives a filament with 0.25 dpf an approximately 3 times larger relative surface than with a filament with 2 dpf.

The still molten thread is therefore not directly exposed to the blowing air according to the invention, but is first cooled in a so-called recess. The solidification point of the yarn must not lie within the recess, because otherwise the strong suction effect of the filaments, which starts early in this titer range, causes large amounts of air to be sucked into the recess, causing turbulence in this region. On the other hand, the solidification point must not be too far outside the recess, otherwise the still soft thread is exposed to the surrounding air for too long without protection.

The freezing point is therefore chosen so that it is just outside the protected recess. In this titer range, the solidification point can be set specifically by the temperature of the polymer. For this purpose, the absolute level of the product temperatures Tscnmeize and T _Be e_z_ng (= Tschmeize + ΔT _SC heating heating) for PET is set in a range from 290 ° C to 318 ° C. The absolute level of the necessary process temperature can be found at

Take-off speeds between 2500 m / min and 3200 m / min depending on the filter surface load according to the following Determine relationship:

^T melt = ^30S - ^{25 '} f

A general problem in the manufacture of ultrafine microfilaments is the strong reaction of spinning stability to temperature inhomogeneities. Additional radiation heating in the area of the recess has proven to be annoying (poor thread uniformity), presumably by reducing the thread tension, in particular the outer filaments, which are thus more sensitive to disturbances from the environment (air movement due to the suction effect of the filaments starting). In the case of radiation heating, the outer filaments are heated on one side, since the side of the filaments which faces the radiating surface is heated more intensely. Recordings with the laser cutting process showed rapid air changes in the recess area caused by the high speed of the filaments in this area. The build-up of a resting, warm air cushion is hindered. An active supply of heat from the outside to the filaments is therefore predominantly by radiation and not by convection.

A passive (non-heated) return, on the other hand, only prevents the outer filaments from cooling too quickly. The length of the passive return cannot be chosen arbitrarily, but is, according to US Pat. No. 4,436,688, a function of the withdrawal speed and the filter surface load, the upper and lower limits of which are determined by the following relationships: L _max = 48, 2 - log v _deduction - 109 [mm]

^L min = ³⁴ > ⁴ X ° S ^ deduction ~ 7 ¹ [ ^m ™]

In this area, a suitable return was selected for the titer range claimed according to the invention.

The selection of a suitable return is a prerequisite for the successful application of the present method, as the following examples (for PET) show (Tab. 3):

Table 3:

The example in the last line was realized with a nozzle package above. Although the values for the thread uniformity are at a good level, a very poor running behavior was achieved with this return. The reason is the cooling of the nozzle plate, which is also reflected in the low values of the thread elongation.

A high level of spinning security is achieved through careful temperature control of the melt by coordinating the size of the heat-transfer surface, the heating temperature and the residence time of the melt in the area of the heating.

The size of the heat-transferring surface and the contact time of the partial melt flow running outside for the heat transfer with the inner wall of the package determine the amount of heat that can be transferred. A simple key figure for the Heat transfer can be defined from the ratio of contact length 1 and contact time t to:

m

melt

1 describes the length of the inner wall of the package along which the external polymer partial stream in the package is heated to an excessive temperature, and t describes the contact time available for heat transfer to the inner wall of the package, t is approximately described by the following

l 'ΛQ ^• P melt' ^ε t =

Relationship: n "'m ^ pH.

where ε stands for the portion occupied by the melt in a specific cross-section of the spin pack and can be constant in sections or a function of the height.

For the amount of heat transferred then, e.g. for a round package:

t - rh

Q melt = ^{~ ~} k - π - D - AT _wall

^ Melt Q

The following area turned out to be suitable for spinning fine microfibers:

The following should preferably be aimed at:

Depending on the throughput, heights of 30 mm to 150 mm have proven to be suitable. Even higher heights lead to excessively long dwell times with corresponding negative effects on product degradation. At a height of 115 mm and a contact time of 7 min, product degradation in the nozzle package of ΔIV = 0.022 dl / g was obtained. The case set over temperature (T _Be eizung ~ T _Sc ι__eize) was 9K. At a height of 50 mm and a contact time of 3 min, a product degradation in the nozzle package of ΔIV = 0.020 dl / g was obtained with PET.

The overtemperature ΔT melt heating set was 21 K. Good spinning results were achieved in both cases.

The partial melt flow near the wall is either heated to the required excess temperature over the entire length H of the melt-contacting inner wall of the spin pack or only on part of the melt-contacting inner wall with an increased excess temperature ΔTs _ch meize-Behe_zung x H / 1 corresponding to the area ratio H / 1. This extra heated surface is then preferably to be provided in the lower part of the spin pack at the level of the nozzle plate in the form of a heating frame with heating to be regulated independently of the spinning beam.

The bicomponent crimping effect described by Fourne in "Synthetic Fibers", p. 310 (Carl Hanser Verlag, Munich, Vienna, 1995) was surprisingly not observed in the claimed titer range with this heating technique. The blowing air was just adjusted so that the speed of the supplied blowing air corresponded to the speed of the air drawn in from the environment itself by the filaments on the side facing away from the blowing. This formed a uniform, stable, flat flow funnel, with its longitudinal axis parallel to the longitudinal axis of the spinning beam, and the otherwise occurring formation of a rope curve along the thread path was suppressed. In addition to thread cooling, the main task of the blown air is to stabilize the position of the. Filament bundle in the blow shaft.

This resulted in a temperature profile that was symmetrical across the longitudinal axis of the beam, in contrast to the asymmetrical temperature profile that can be achieved with the usual cross-flow blowing (see Fourne, Figure 3.12). Uster HI values of <0.5% are thus achieved.

For the method according to the invention, it is equally necessary to set a predetermined temperature profile by means of the nozzle heating described above and to set a symmetrical blown air profile.

Because the filaments located on the axis of the flow funnel are in the equilibrium of forces of the thread friction forces of the supplied and sucked-in air, the deflection of the individual filaments transversely to the longitudinal axis of the spinning beam is less than 20 mm. According to Fourne (p. 195), vibrations in the blow shaft of 30 - 100 mm are otherwise common.

Due to the warping area close to the nozzle, the strong and early suction effect of the filament coulter means that the thread curtain is also blown through in no longer take place in the upper area of the blow duct. Therefore, pressure equalization and laminarization of the air sucked in from the environment is required in this area. The amount of air sucked in in this area can be controlled directly via the targeted setting of a pressure loss, for example by a different number of fine fabric layers or perforated sheets.

The sucked-in air is passed through a device for pressure equalization before reaching the filaments and, if necessary, laminated by guide elements (e.g. honeycomb straightener).

The pressure loss caused by the thread take-off depends on the take-off speed ^ zu, single filament titer (in denier) and number of filaments n according to the following relationship:

In order for the filaments to be adequately supplied with cooling air, the additional pressure loss to be applied via a pressure equalization device must not be greater than (2 to 3) • Δp.

The individual bundles of threads are separated by dividers so that a symmetrical air profile is created transverse to the longitudinal axis of the spinning beam. A preferred embodiment of the separating plates is the arrangement of a separating plate common to two adjacent bundles of threads on the division axis (Fig. 4, left). In a further preferred embodiment, two separating sheets per thread bundle are arranged following the thread run and inclined in the direction of the thread axis, symmetrically to this (Fig. 4 right). Sealing systems at points A prevent the intake of incorrect air. The chambers formed in this way are open towards the bottom, towards the rear and towards the front. To dampen the compensating flow against the thread draw-off direction, it is expedient to close the passage area downward so that the filament bundle can just pass through. The passage surface itself can be largely closed up to the thread bundle or can be porous (e.g. perforated plate) in order to counter the compensating flow with a targeted resistance.

The process outlined above with reference to PET can be applied in an analogous manner to other polyesters or polyamides, only the differing melting temperatures and viscosities having to be taken into account.

Example 1:

PET polymer with an IV of 0.635 dl / g was melted in a conventional extruder and fed to the spinning beam at a product temperature of 300 ° C. via static mixers and the product line. The spinning beam with 6-gang spinning pump, melt distributor and 6 nozzle packs was set to 311 ° C. The throughput per partial pump flow was 19.1 g / min. The melt was in the nozzle package first through two layers of metal sand with increasingly finer grain, then through a multi-layer metal mesh filter, the finest layer of which consisted of a twill weave with 5 μm, and then through a distributor plate and a second multi-layer metal mesh filter, the finest layer consisted of a twill braid with 15 μm, an unmounted filter disk made of metal mesh filter with 17000 mesh / cm ² lying flat on the nozzle plate and subsequently through the nozzle plate with a diameter of 96 mm, the fine bores of which had a capillary diameter of 0.12 mm and a capillary length of 0.48 mm, pressed. The distance between the fine bores on the nozzle plate was 5.8 mm.

The filaments emerging from the nozzle passed through an unheated zone largely shielded from the direct blowing directly after the nozzle of 55 mm in length.

Immediately after this area, the actual warping to almost the final speed took place, whereby here the central and edge filaments had approximately the same speeds due to the radial higher heating applied in the package (checked with LDA measurement), before they subsequently went into an all-round chambered shaft Transverse blowing occurred, with blowing air at a speed of 0.27 m / s, over a length of 1.5 m. The side opposite to the blowing was initially shielded over a length of 150 mm with a combination of coarse sieve with approx. 600 mesh / cm ² and perforated plate, and then over a length of approx. 500 mm only with perforated plate and holder. Conventional shaft door designs were used in the lower area. Through this side, the thread in the upper area, by means of controlled self-suction of the filaments, was supplied with ambient air of approximately the same order of magnitude as on the blower side of the transverse blowing. 485 mm after emerging from the spinneret, the filaments were loaded with preparation in a double oiler system, using oiling stones with special ceramic surfaces. An emulsion with a water content of <10% was applied, with 2/3 of the amount applied to the thread in the first oiler being fed to the thread bundle and the remaining third in the second oiler. The thread tension measured after the oiler was 26 cN. The thread was bundled through the rest of the blowing and drop chute over a distance of 2 m before being subjected to an air pressure of 0.6 bar in an interlacer. An interlacer with an adapted special surface was used for this. The thread bundle was then fed directly to the winder via two S-shaped godets, checked by means of a capillary break sensor and wound up with a thread tension of 7 g. Error-free coils with a good structure were achieved. The single filament titer was 0.21 dpf.

The risk of breakage is particularly pronounced with these titers. For this reason, all of the ceramic guide elements (thread guides, oilers) that come into contact with the yarn have been equipped with surfaces optimized for friction pairing. The shape of the thread oiler has also proven to be crucial. When comparing the voltage differences before / after the oiler with untreated and treated surface and a correspondingly adapted shape, the voltage could be reduced by up to 20% with correspondingly positive effects on the number of capillary breaks on the oiler. It is noteworthy that, in contrast to standard yarns, local knots no longer form in the yarn after interlacing. A continuous one is preferred Braiding, which leads to a very uniform puffy yarn being obtained after texturing.

Any conventional titers in the usual fineness ranges for normal and high count titers can be run on the spinning system designed according to this process without major modifications.

Example 2:

The procedure was the same as in Example 1, except that the controlled self-suction, contrary to the cross-blowing, was investigated in connection with the strict chamber division between the thread bundles of a spinning position. The results are summarized in Table 4:

Table 4:

Example 3:

The procedure was the same as in Example 1, but the oil design was varied, as explained in Table 5. It becomes clear that in addition to the running stability, the textile parameters are also decisively influenced:

Table 5:

Example 4:

From the low bending resistance moment W of the yarn produced _{according to} the invention (for example: W ₍ o, _26dpf) = 9-10 ^"18 mm ³ " W <ι, ₀ dp_> = 100-10 ^"18 mm ³ ) there is initially no imperative for an entangling, since a good thread closure can already be expected through self-interweaving of the filaments. With such a fine filament titer, damage to the yarn in the interlacer is also possible. Surprisingly, angling in connection with the use of godets has proven to be advantageous, since this ensures reliable guidance around the godets, particularly when the necessary low winding tensions are involved. Otherwise, a stable spinning run was difficult, at least with texturing preparations. Especially for the use of texture preparations, it has proven to be useful to fish in front of the godets. Despite the highest spinning tensions occurring in the process, there is no thread damage when using special surface-treated interlacers. This means that conventional godet surfaces could also be used for such fine titers.

The interlacer influence was investigated on the basis of filaments obtained according to Example 1 and the results are summarized in Table 6. Table 6:

Claims

claims

1. A process for producing a synthetic ultra-fine continuous yarn based on polyester or polyamide in the range 0.25 to 0.9 denier per POY filament by melt spinning at take-off speeds between 2000 and 6000 m / min, characterized in that (i) as a filtration medium A sequence of different fabric layers with the finest mesh sizes from 5 to 15 µm in combination with or without fine steel sand in the grain size 88 to 250 μm steel sand is used in the spinning package and either steel sand or corresponding internals with finest pore openings of 50 to 1000 are used to shear the melt μm are used in the spinning package in such a way that a total package pressure of at least 105 bar with filter surface loads of 0.25 to 0.80 g / min / cm ^{2 is} achieved,

(ii) the hole density of the nozzle plates used is between 1.5 and 6.0 holes / cm ² ,

(iii) the diameter d of the capillary holes in the nozzle plate based on the relationship

is chosen so that the apparent wall shear rate of the melt within the capillaries between 5. 000 and 25. 000 s ^"1 is

(iv) the length L of the capillaries based on the relationship

is selected so that the melt pressure in front of the nozzle plate is between 50 and 100 bar and is preferably between 60 and 100 bar,

(v) is formed a balanced temperature profile in the cross section of the filament bundle before reaching the draft zone, wherein the distance h from the nozzle plate on which this temperature profile is reached is smaller than the distance of the solidification point h _0, ₉ 8% from the nozzle plate and the solidification point is chosen such that it is located directly subsequent to the protected return and h _0, ₉ 8% is defined by the nozzle plate by the following relationship:

where h ₀ , ₉ 8% above the temperature of the polymer at the entrance of the spin pack depending on the filter surface load is adjusted according to the following relationship: Tschmeize = 308-25 fFiler [° C], f _F iiter in g / min / cm ^2,

(vi) in order to achieve the balanced temperature profile in the filament bundle, an excess temperature (T _Ra n_ - T _Ran _) is set, which is measured as the surface temperature difference between the center and edge of the nozzle plate and can be set in the claimed titer range using the temperature difference from the spinning beam heating and the polymer (T _SC hmeize - Tßeneizung) depending on the filament throughput m _F ii, the take-off speed and the filter area A _fi ι _te as follows:

T —T = f '(T —T Λ

Heating melt edge center

4K ≤ (T _n , -r_) ≤ 13K and center edge

(vii) a precisely defined amount of heat is transferred to the polymer part stream running outside in the spin pack, which is determined by the ratio 1 / t, 1 describing the length of the packet inner wall along which the polymer part stream running outside is heated to an excessive temperature in the package, and t describes the contact time available for heat transfer to the package inner wall, approximately determined by the following

^{l, Λ} Q ^' PSmelt ^ε t = -

Relationship ϊl _' ϊ _τ? -, 'where ε for that of the

Melt taken in a certain proportion

Cross-section of the spin pack stands and can be constant in sections or can be a function of the height and that

Ratio 1 / t is selected within the following range: 0.6 cm / min <1 / t <3.8 cm / min,

(viii) the still molten thread is not directly exposed to the blown air, but is first cooled in a so-called recess, the recess being smaller than the delay point,

(ix) a velocity profile of the blowing, which is symmetrical to the longitudinal axis of the beam, is set, with a controlled self-suction taking place on the side facing away from the blowing by means of corresponding flow resistances,

(x) the individual bundles of threads are separated by dividers,

(xi) all organs coming into contact with the yarn, such as oilers, guide organs and treatment organs made of ceramic, are equipped with friction-optimized surfaces, so that after passing through the organs, a maximum tension build-up in the yarn takes place from 60 to 110%,

(xii) optionally the thread bundles are subjected to entangling, and

(xiii) the freshly spun yarn with a

_{Winding tension} ^σ deduction ^~ \ U, ^J ... ¹ , 1) _{fgχ is} wound up.

2. The method according to claim 1, characterized in that a second immiscible amorphous polymer is added to the polyester or polamide in an amount of 0.05 to 5 percent by weight.

3. The method according to claim 2, characterized in that the amorphous polymer is a copolymer which is composed of at least two of the following monomer units:

0 to 95% by weight of A, where A is a monomer of the formula CH ₂ = C (R) -COOR ¹ , with R equal to -H or -CH ₃ and R ¹ equal to straight-chain or branched Ci-i _. -Alkyl or cyclohexyl, 0 to 40% by weight B, where B is a monomer consisting of maleic acid or maleic anhydride, and 5 to 85% by weight C, where C is a monomer consisting of styrene or methyl-substituted styrene, and where ( % By weight A +% by weight B +% by weight C) = 100.

4. The method according to any one of claims 1 to 3, characterized in that the residence time of the melt within the spin pack by internals so is set so that 12 minutes are not exceeded and 5 minutes are not exceeded.

5. The method according to any one of claims 1 to 4, characterized in that the partial melt stream close to the wall increases either over the entire length H of the melt-contacted inner wall of the spin pack to the required excess temperature or only on part of the melt-contacted inner wall with an area ratio H / 1 accordingly About temperature (T _be heating - T _SC hmeize) x H / is heated. 1

6. The method according to any one of claims 1 to 5, characterized in that the diameter d of the individual capillary bores in the nozzle plate is not constant over the cross-section of the nozzle plate, but is inversely proportional to the temperature gradient measured on the surface of the nozzle plate, the Deviation between the center and edge-near holes is a maximum of 0.2 d.

7. The method according to any one of claims 1 to 6, characterized in that the yarn is wound up at take-off speeds between 2000 and 6000 m / min and then on a stretch texturing unit at speeds of 400 to 1000 m / min to a final titer of 0.15 up to 0.52 denier per filament.

8. The method according to any one of claims 1 to 6, characterized in that the yarn is wound up at take-off speeds of between 2000 and 6000 m / min and then further processed on a stretching unit at speeds of 400 to 1000 m / min. We work up to a final titer of 0.15 to 0.52 denier per filament.

9. The method according to any one of claims 1 to 6, characterized in that the yarn is drawn at take-off speeds between 2000 and 60,000 m / min to a final denier of 0.15 to 0.52 denier per filament and then wound up, the stretching on the final titer takes place after spinning between two godet duos.

10. Ultra-fine continuous POY yarn based on polyester or polyamide, to which up to 5% by weight of a second, immiscible amorphous polymer can optionally be added, with a titer in the range from 0.25 to 0.9 denier per filament, an elongation at break of 100-145%, a specific tensile strength between 18 and 33 cN / tex and a uniformity of the yarn, expressed in terms of the undamped Uster value, between 0.5 and 1.0%, characterized in that the yarn according to the Method of one of claims 1 to 6 was obtained.

11. Ultra-fine drawn or draw-textured continuous yarn based on polyester or polyamide, to which up to 5% by weight of a second, immiscible amorphous polymer can optionally be added, with a titer in the range from 0.15 to 0.52 denier per filament , characterized in that the yarn was obtained by the method of one of claims 7 to 9.