EP1208253A1

EP1208253A1 - Hmls-fibers made of polyester and a spin-stretch process for its production

Info

Publication number: EP1208253A1
Application number: EP00951438A
Authority: EP
Inventors: Joachim Cziollek; Werner Mrose; Dietmar Wandel; Helmut Schwind; Wolfgang Janas; Werner Ude
Original assignee: ZiAG Plant Engineering GmbH; Roehm GmbH Darmstadt
Current assignee: Roehm GmbH Darmstadt; LL Plant Engineering AG
Priority date: 1999-08-10
Filing date: 2000-07-25
Publication date: 2002-05-29
Anticipated expiration: 2020-07-25
Also published as: US6740404B1; CN1370248A; KR20020036843A; DE50007704D1; ATE275650T1; EA004429B1; JP2003506587A; WO2001011122A1; CN1168856C; EA200200196A1; DE19937728A1; AU6437200A; EP1208253B1

Abstract

HMLS filaments consisting of a polyester, from 0.1 to 2.5% by weight of an incompatible, thermoplastic, amorphous, polymeric additive having a glass transition temperature of from 90 to 170° C. and a ratio of its melt viscosity to that of the polyester component of from 1:1 to 7:1, and from 0 to 5.0% by weight of conventional additives, where the polymeric additive is present in the filaments in the form of fibrils having a mean diameter of <=80 NM.Process for the production of these HMLS filaments by static mixing with shearing of the polyester and of the polymeric additive and, optionally, of the additives, spinning of the mixture at a spinning take-off speed of from 2500 to 4000 m/min to give spun filaments which are stretched, heat-set and wound up, where the concentration of the polymeric additive is determined as a function of the pre-specified spinning take-off speed and the desired birefringence of the spun filaments.

Description

HMLS threads made of polyester and spin stretching process for their production

Description:

The invention relates to HMLS threads made of polyester with a tensile strength of> 70 cN / tex, a LÄSE 5 of> 35 cN / tex and a hot air shrinkage at 160 ° C of 1.5-3.5% and a spin stretching process Production of the HMLS threads. HMLS threads are understood to mean multifilament stretched polyester threads with high modulus and low shrinkage (high modulus,] _ow shrinkage).

Multifilament polyethylene terephthalate filaments with high LÄSE 5 (the specific force which corresponds to an elongation of 5% in the force-elongation diagram) and low thermal shrinkage and process for their

Manufacture is known, the yarns being used for industrial applications such as tire cord. Et al Such methods are described in the patents US 5,067,538, EP 0423 213 B, US 4,101,525, USP 5,472,781. In these publications it becomes clear that with increasing spinning take-off speed the applicable one

Stretch ratio decreases, the steepness of the force-elongation diagram, d. H. the LÄSE 5 rises, the thermal shrinkage decreases and the achievable strength decreases. The decrease in the applicable stretching ratio is due to the increase in the orientation in the filament and is characterized by an increase in the birefringence of the filament.

In US Pat. No. 4,491,657, spinning speeds of 3000 m / min are achieved, and in the subsequent stretching process only tensile strengths of around 62 cN / tex are achieved. In EP 0 423 213 B, Tables 2 and 5 show that in the Stretch ratios that can be used in practice can reach a tensile strength of 69 cN / tex even at spinning speeds of 2900 m / min.

The drop in the applicable draw ratio with increasing spinning speed is increased by higher spinning viscosities, as shown in US Pat. No. 5,067,538. The applicable stretching ratio is already so low at an intrinsic viscosity of the polymer of 0.88 dl / g that final speeds over 6000 m / min are no longer possible. EP 0 169 415 A describes a

Polyester filament described with an intrinsic viscosity above 0.9 dl / g. The stretching ratios that can be used for the different spinning speeds are so low that efficient top speeds of over 6000 m / min are only possible at very high spinning take-off speeds of over 3500 m / min. In EP 0 546859 A, a polyester thread is produced at spinning take-off speeds of 2500 to 4000 m / min. Here, too, the low stretchability, even at spinning take-off speeds of 4000 m / min, gives high speeds of just 6000 m / min for high-speed spinning draws, the tensile strength being less than 65 cN / tex.

In EP 0438421 B1 it is also made clear that the high-speed spinning draw leads to threads with many capillary breaks. Therefore, a device that defines the stretching point is introduced, which in the best case lowers the capillary break level of such HMLS threads to 20 defects / 10 km.

Drawn yarns with tensile strengths above 70 cN / tex and low thermal shrinkage, produced at spinning speeds above 2500 m / min, are also described in EP 0526 740 B. These yarns consist of a polyester raw material based on a copolymerization modified polyethylene terephthalate. These modification components are incorporated into the polymer chain during the polymer formation process, which impairs the flexibility of the spinning operation.

Furthermore, it is known from WO 99-07927A1 that the elongation at break of pre-oriented polyester filaments (POY) spun at take-off speeds of at least 2500 m / min by adding amorphous, thermoplastically processable copolymers based on styrene,

Acrylic acid and / or maleic acid or their derivatives can be increased without addition to the elongation at break of polyester filaments spun under the same conditions. Information on the production of HMLS threads in the spin stretching process is not included.

EP 0047 464 B relates to an undrawn polyester yarn, the addition of 0.2-10% by weight of a polymer of the type - € H ₂ -CR ₁ R ₂ ) - _π , such as poly (4-methyl-l- penten) or polymethyl methacrylate, improved productivity is obtained by increasing the elongation at break of the filament at speeds between 2500-8000 m / min. A fine and uniform dispersion of the additive polymer by mixing is necessary, and the particle diameter must be <1 μm to avoid fibril formation. In addition to the chemical additive structure, which hardly allows the additive molecules to stretch, the low mobility and the compatibility of polyester and additive should be decisive for the effect.

EP 0631 638 B describes fibers composed predominantly of PET, which contains 0.1-5% by weight of a 50-90% imidized polymethacrylic acid alkyl ester. The fibers obtained and subsequently finally drawn at speeds of 500-10,000 m / min are said to be higher Have initial module. In the examples of industrial yarns, however, the influence on the module cannot be easily understood; in general, the strengths achieved are low, which is a considerable disadvantage for this product.

The present invention has for its object to provide HMLS threads with a tensile strength> 70 cN / tex, a LÄSE 5> 35 cN / tex and a hot air shrinkage at 160 ° C of 1.5 to 3.5%, and to create a spin-stretching process for their production, at which final speeds of over 6000 m / min can be reached, even with highly viscous polyester, and with a minimization of the number of capillary breaks. The desired HMLS threads should be able to be produced at high spinning speeds without chemical modification of the polyester raw material being necessary, which would reduce the flexibility of the spinning plant. In addition, it should be possible to produce the HMLS threads tailor-made for the respective application by setting the birefringence in the spinning thread largely independently of the spinning take-off speed. Birefringence should be adjustable in the range of 30 ^• 10 ^"3 to 55 ^• 10 ^{~ 3} .

The object on which the invention is based is achieved by HMLS threads made of polyester and a spin-stretching method for their production in accordance with the details of the claims.

Among polyester here are poly (C ₂ _ ₄ alkylene) terephthalates, which up to 15 mol% of other dicarboxylic acids and or diols, such as. B. isophthalic acid, adipic acid, diethylene glycol, polyethylene glycol, 1,4-cyclohexanedimethanol, or the other C ₂ _ ₄ alkylene glycols, may be understood. Polyethylene terephthalate with an intrinsic viscosity (IV) in the range from 0.8 to 1.4 dl / g is preferred, Polypropylene terephthalate with an IV of 0.9 to 1.6 dl / g and polybutylene terephthalate with an IV of 0.9 to 1.8 dl / g. Usual additives, such as dyes, matting agents, stabilizers, antistatic agents, lubricants, branching agents, can be added to the polyester or polyester additive mixture in amounts of 0 to 5.0% by weight without disadvantage.

According to the invention, an amorphous, thermoplastically processable, incompatible, polymeric additive, which has a glass transition temperature of 90 to 170 ° C., is added to the polyester in the melt, the ratio of the melt viscosity of the additive to the melt viscosity of the polyester being 1: 1 to 7: 1 , the mixture is treated in a static mixer under shear, the shear rate being 16 to 128 s ^"1 , and the product of the shear rate and the 0.8th power of the residence time in seconds is set to a value of at least 250, and the The mixture is then spun at a spinning draw speed v of 2500 to 4000 m / min, stretched, thermally treated and wound up at> 6000 m / min.

The additive polymers to be added to the polyester, provided they have the physical properties mentioned, can have a different chemical composition. Three different types of polymer are preferred, namely

1. A polymer which contains the following monomer units:

A = acrylic acid, methacrylic acid or CH ₂ = CR - C00R ¹ , where R is an H atom or a CH ₃ group and R 'is a C ^^ - alkyl radical or a C ₅ . ₁₂ -cycloalkyl radical or a C ₆ . ₁₄ aryl radical, B = styrene or C ,. _3- alkyl substituted styrenes,

the polymer consisting of 60 to 100% by weight of A and 0 to 40% by weight of B, preferably of 83 to 98% by weight of A and 2 to 17% by weight of B, and particularly preferably of 90 to 98% by weight of B A and 2 to 10 wt .-% B (sum = 100 wt .-%).

2. A polymer which contains the following monomer units:

C = styrene or C ^ alkyl-substituted styrenes,

D = one or more monomers of the formula I, II or III

R, - C = C - R, R, - C - COOH Ri - C - C = 0

II \ no = c _{N /} c = o R - C - COOH R ₇ - C - C = 0

(I) (II) (III)

where R _lt R ₂ and R _{3 are} each an H atom or a C ₁₅ alkyl radical or a C ₅ ₁₂ cycloalkyl radical or a C ₆ ₁₄ aryl radical,

wherein the polymer from 15 to 100 wt .-% C and 0 to 85 wt .-% D, preferably from 50 to 95 wt .-% C and 5 to 50 wt .-% D and particularly preferably from 70 to 85 wt. -% C and 15 to 30 wt .-% D, the sum of C and D together making 100%. 3. A polymer which contains the following monomer units:

E = acrylic acid, methacrylic acid or CH ₂ = CR - COOR ', where R is an H atom or a CH ₃ group and R' or a C ₅ . Is _12- cycloalkyl or a C ₅ _ ₁₄ aryl radical,

F = styrene or C 1-4 alkyl-substituted styrenes,

G one or more monomers of the formula I, II or III

K ^ - LKR— C— COOH R— C— C = 0 II) θ o = c _/ c = o R— C— COOH R - C— C = 0}

I (I) (II) (III)

R 3

where R ₁₅ R ₂ and R _{3 are} each an H atom or a C _1-15 alkyl radical or a C _5.12 cycloalkyl radical or a C ₅ . ₁₄ -

Aryl radical,

H = one or more ethylenically unsaturated monomers copolymerizable with E and / or with F and / or G from the group consisting of α-methyl styrene, vinyl acetate,

Acrylic acid esters, methacrylic acid esters other than E, vinyl chloride, vinylidene chloride, halogen-substituted styrenes, vinyl esters, isopropenyl ethers and dienes,

the polymer consisting of 30 to 99% by weight E, 0 to 50% by weight F,> 0 to 50% by weight G and 0 to 50% by weight H, preferably 45 to 97% by weight E, 0 to 30% by weight F, 3 to 40% by weight G and 0 to 30% by weight H and particularly preferably consists of 60 to 94% by weight of E, 0 to 20% by weight of F, 6 to 30% by weight of G and 0 to 20% by weight of H, the sum of E, F, G and H together results in 100%.

Component H is an optional component. Although the advantages to be achieved according to the invention can already be achieved by polymers which have components from groups E to G, the advantages to be achieved according to the invention also occur if further monomers from group H are involved in the construction of the polymer to be used according to the invention.

Component H is preferably selected so that it has no adverse effect on the properties of the polymer to be used according to the invention. Component H can u. a. can be used to modify the properties of the polymer as desired, for example by increasing or improving the flow properties when the polymer is heated to the melting temperature, or to reduce residual color in the polymer or by using a polyfunctional monomer to do so and to introduce some degree of crosslinking into the polymer. In addition, H can also be chosen so that a copolymerization of components E to G is possible or supported in the first place, as in the case of MA and MMA, which do not copolymerize per se, but copolymerize without problems when a third component such as styrene is added.

Suitable monomers for this purpose include u. a. Vinyl esters, esters of acrylic acid, for example methyl and ethyl acrylate, esters of methacrylic acid which differ from methyl methacrylate, for example butyl ethacrylate and ethylhexyl methacrylate,

Vinyl chloride, vinylidene chloride, styrene, α-methyl styrene and the various halogen-substituted styrenes, vinyl and isopropenyl ether, dienes, such as 1,3-butadiene and divinylbenzene. The color reduction of the polymer can, for example, particularly preferably be achieved by using an electron-rich monomer, such as, for example, a vinyl ether, vinyl acetate, styrene or α-methyl styrene. Particularly preferred among the compounds of component H are aromatic vinyl monomers, such as styrene or α-methyl styrene.

The preparation of the polymers to be used according to the invention is known per se. They can be prepared in bulk, solution, suspension or emulsion polymerization. Helpful hints can be found with regard to substance polymerization in Houben-Weyl, Volume E20, Part 2 (1987), page 1145ff. Information on solution polymerization can be found on page 1149ff, while the

Emulsion polymerization is carried out and explained there on page 1150ff.

Bead polymers whose particle size is in a particularly favorable range are particularly preferred in the context of the invention.

The polymers to be used according to the invention, for example by mixing into the melt of the fiber polymers, are preferably in the form of particles with an average diameter of 0.1 to 1.0 mm. However, larger or smaller beads or granules can also be used, although smaller beads place special demands on logistics, such as conveying and drying.

The imidized polymer types 2 and 3 can be prepared from the monomers using a monomeric imide or by subsequent complete or, preferably, partial imidization of a polymer containing the corresponding maleic acid derivative. These additive polymers are obtained, for example, by completely or preferably partially reacting the corresponding polymer in the melt phase with ammonia or a primary alkyl or arylamine, for example aniline (Encyclopedia of Polymer Science and Engineering Vol 16 [1989], Wiley-Verlag, page 78). All of the polymers according to the invention and, if given, their non-imidized starting polymers are commercially available or can be prepared by a process which is familiar to the person skilled in the art.

The concentration c of the polymeric additive in% by weight in the polyester is determined as a function of the specified take-off speed v in m / min and the desired birefringence of the filament Δn according to the following formulas:

in which

100 ^■ (Δπ ₀ - An) f, = ₆ ', ^v "" ° ""^; , (2) Δn ₀ (7.2589 • 10 ^"6 • v ² - 7.7932 • 10 ^{" 2} • v + 236.0755)

100 • (Δπ ₀ - Δn) f ₂ = (3)

Δπ ₀ (5.9391 • 10 ^" 6.3763 • 10 ^{" 2} • v + 193.1527)

Δn = birefringence of the polyester filament according to the invention with additive added,

Δn ₀ = birefringence of spun threads made of polyester without additive, produced under the same spinning conditions as those according to the invention, Δn <Δn ₀ x = 1 for additive polymers of type 1 or 3, and x = 2.8 for additive polymers of type 2 (without acrylic compound).

The additive polymer is incompatible with the polyester, which means that the additive is largely insoluble in the polyester matrix. The polyester and the additive polymer form two phases that can be distinguished microscopically. Furthermore, the copolymer must have a glass transition temperature (determined by DSC at 10 ° C / min

Heating rate) of 90 to 170 ° C and can be processed thermoplastically.

The melt viscosity of the copolymer should be chosen so that the ratio of its extrapolated to the measuring time is zero

Melt viscosity, measured at an oscillation rate of 2.4 Hz and a temperature which is equal to the melting temperature of the polyester plus 34.0 ° C (for polyethylene terephthalate 290 ° C) relative to that of the polyester, measured under the same conditions, between 1: 1 and 7: 1. That is, the melt viscosity of the polymer is at least equal to or preferably higher than that of the polyester. Optimal efficiency is only achieved by choosing a specific viscosity ratio of additive and polyester. With such an optimized viscosity ratio, it is possible to minimize the amount of additive additive, which makes the process particularly economical. Surprisingly, the viscosity ratio determined according to the invention as ideal for the use of polymer mixtures for the production of HMLS threads is above the range which is indicated in the literature as being favorable for mixing two polymers. In contrast to the prior art, polymer blends with high molecular weight additive polymers were distinguished to spin.

Due to the high flow activation energy of the additive polymers, the viscosity ratio increases drastically in the area of the thread formation after the polymer mixture has emerged from the spinneret. The flow activation energy (E) is a measure of the rate of change of the zero viscosity as a function of the change in the measuring temperature, the zero viscosity being the viscosity extrapolated to the shear rate 0. (M. Pahl et al., Practical Rheology of Plastics and Elastomers, VDI-Verlag, Düsseldorf (1995), pages 256 ff.). By choosing a favorable viscosity ratio, a particularly narrow particle size distribution of the additive in the polyester matrix is achieved and by combining the viscosity ratio with a flow activation energy of significantly more than that of the polyester (PET about 60 kJ / mol), i.e. H. The fibril structure of the additive in the filament is obtained at more than 80 kJ / mol. The glass transition temperature, which is high compared to polyester, ensures that this fibril structure is quickly consolidated in the spun thread. The maximum particle sizes of the additive polymer are about 1000 nm immediately after emerging from the spinneret, while the average particle size is 400 nm or less. After warping below the spinneret and stretching, fibrils with an average diameter <80 nm are formed.

The ratio of the melt viscosity of the copolymer to that of the polyester under the above-mentioned conditions is preferably between 1.5: 1 and 5: 1. Under these conditions, the average particle size of the additive polymer is 120-300 nm immediately after it emerges from the spinneret, and this results Fibrils with an average diameter of approximately 40 nm. The additive polymer is mixed with the matrix polymer by adding it as a solid to the matrix polymer chips in the extruder inlet with a chip mixer or gravimetric metering, or alternatively by melting the additive polymer, metering by means of a gear pump and feeding it into the melt stream of the matrix polymer. So-called masterbatch techniques are also possible, the additive being present as a concentrate in polyester chips which are later added to the matrix polyester in the solid or molten state. The addition to a part of the stream of the matrix polymer, which is then mixed into the main stream of the matrix polymer, is also practical.

A homogeneous distribution is then produced by mixing using a static mixer. Advantageously, a specific particle distribution is set by the specific choice of mixer and the duration of the mixing process before the melt mixture is passed on through product distribution lines to the individual spinning stations and spinnerets. Mixers with a shear rate of 16 to 128 sec ^"1 have proven successful. The product of the shear rate (s ^{" 1} ) and the 0.8th power of the residence time (in sec) should be at least 250, preferably 350 to 1250. Values above 2500 are generally avoided in order to keep the pressure drop in the pipes limited.

Here, the shear rate is defined by the shear rate in the empty tube (s ^"1 ) times the mixer factor, the mixer factor being a characteristic parameter of the mixer type. For Sulzer SMX types, for example, this factor is about 7-8. The shear rate γ in the empty tube is calculated according to

4 • 10 "

7 = R. fin L and the dwell time t (s) according to

V ₂ - ε - δ • 60 F where

F = delivery rate of the polymer (g / min) V ₂ = inner volume of the empty pipe (cm ³ ) R = empty pipe radius (mm) ε empty volume fraction (for Sulzer-SMX types 0.84 to 0.88) δ = nominal density of the polymer mixture in the Melt (about 1.2 g / cm ³ )

Both the mixing of the two polymers and the subsequent spinning of the polymer mixture takes place at temperatures, depending on the matrix polymer, in the range from 220 to 320 ° C., preferably at (melting temperature of the matrix polymer + 34) + 25 / - 20 ° C. , Temperatures of 270 to 315 ° C. are preferably set for PET.

The production of the HMLS threads from the inventive

Polymer blends by spinning at take-off speeds of 2500 to 4000 m / min, drawing, heat setting and winding are carried out using known spin stretching devices in the same way as for polyester without an additive. Here, the filter package according to the known prior art is equipped with filter devices and / or loose filter media.

After the shear and filtration treatment in the nozzle pack, the molten polymer mixture is pressed through the holes in the nozzle plate. The melt threads are in the subsequent cooling zone cooled below its solidification temperature by means of cooling air, so that sticking or upsetting on the following thread guide member is avoided. The cooling air can be supplied from a climate system by transverse or radial blowing. After cooling, the spinning threads are subjected to spin preparation, drawn off at a defined speed via godet systems, then drawn, heat-set and finally wound up. Advantageously, thread interlacing devices can be included in the process.

It is typical of HMLS threads made of polyester that they are large

Direct melt spinning systems are manufactured in which the melt is distributed over long heated product lines to the individual spinning lines and within the lines to the individual spinning systems. Here, a spinning line represents a series of at least one row of spinning systems and a spinning system is the smallest spinning unit with a spinning head that contains at least one spinneret package including spinneret plates. In such systems, the melt is subject to high thermal loads with residence times of up to 35 minutes. Due to the high thermal stability of the additive, the effectiveness of the polymer additive according to the invention does not lead to any notable restrictions in its action, so that a small amount of additive <2.5% and in many cases <1.5% is sufficient despite high thermal stress.

The properties of the additive polymer and the mixing technology cause the additive polymer to form spheroidal or elongated particles in the matrix polymer immediately after the polymer mixture emerges from the spinneret. The best conditions were found when the mean particle size (arithmetic mean) d ₅₀ <400 nm and the proportion of particles> 1000 nm in a sample cross-section was less than 1%. The influence of these particles by the spinning draft or the drawing could be verified analytically. New investigations of the threads by the TEM method (transmission electron microscopy) have shown that there is a fibril-like structure. The mean diameter of the fibrils was estimated at approximately 40 nm and the length / diameter ratio of the fibrils was> 50. These fibrils cause a "micro-roughness" of the fiber surface, which leads to improved cord / rubber adhesion and when using the yarn z. B. is highly valued as a tire cord. If these fibrils are not formed or if the additive particles are too large in diameter after exiting the spinneret or if the size distribution is too uneven, which is the case if the viscosity ratio is insufficient, the effect will be lost.

Furthermore, a glass transition temperature of 90 to 170 ° C., and preferably a flow activation energy of the additive polymers of at least 80 kJ / mol, that is to say a flow activation energy higher than that of the polyester matrix, is required for the effectiveness of the additives according to this invention. Under this condition, it is possible for the additive fibrils to solidify in front of the polyester matrix and to absorb a significant proportion of the spinning tension present. The additives to be used with preference are also distinguished by a high thermal stability. So are in the direct spinning systems operated at large dwell time and / or high temperature

Loss of effectiveness due to additive decomposition minimized.

The drawing is carried out in a manner known per se in at least one stage between differently heated godet systems, preferably in two stages. The stretching of the spinning thread is preferably carried out using a draw ratio DR, for which the Withdrawal speed v in m / min and the concentration c of the additive copolymer in% by weight applies:

f ₃ <DR <f ₄ (4)

in which

-4 ι-4 f \ = -5 ^• 10 1.6 ^• 10 ^• v ^• c / x + 0.98 ^• c / x + 3.55 (5)

f ₄ = -5 ^• 10 ^{"4 •} v - 2.4 ^• 10 ^" " ^• v ^• c / x + 1.46 ^• c / x + 3.55 (6)

With multi-stage stretching, DR is the product of the individual stretching ratios. The winding speed is equal to the product of the spinning speed v, the draw ratio DR and the relax ratio.

The HMLS threads according to the invention have at least the same quality values as yarns produced analogously without polymeric additive.

The property values given in the examples below and in the text above were determined as follows:

Additive fibrils: The microtome thin sections of the threads were examined by means of transmission electron microscopy and subsequent image analysis, in which the diameter of the fibrils was assessed and the length was estimated from the particle diameter determined in samples immediately after the spinneret.

The intrinsic viscosity was determined on a solution of 0.5 g polyester in 100 ml of a mixture of phenol and 1,2-dichlorobenzene (3: 2 parts by weight) at 25 ° C. To determine the melt viscosity (initial viscosity), the polymer was dried in vacuo to a water content of <1000 ppm (polyester <50 ppm). The granules were then introduced into the temperature-controlled measuring plate in a cone-plate rheometer, type UM100, Physica Meßtechnik GmbH, Stuttgart / DE, while being coated with nitrogen. The measuring cone (MK210) was positioned on the measuring plate after the sample had melted, ie after approx. 30 seconds. The measurement was started after a further heating-up period of 60 seconds (measuring time = 0 seconds). The measuring temperature was 290 ° C. for polyethylene terephthalate and additive polymers to which polyethylene terephthalate was added, or was equal to the melting temperature of the polyester concerned plus 34.0 ° C. The measuring temperature thus determined corresponds to the typical processing or spinning temperature of the respective polyester. The amount of sample was chosen so that the rheometer gap was completely filled. The measurement was carried out in oscillation with the frequency 2.4 Hz (corresponding to a shear rate of 15 sec ^"1 ) and a deformation amplitude of 0.3, and the amount of the complex viscosity was determined as a function of the measurement time. The initial viscosity was then determined by linear regression converted to zero measurement time.

To determine the glass transition temperature and the melting temperature of the polyester, the polyester sample was first melted at 310 ° C. for 1 minute and immediately quenched to room temperature. The glass transition temperature and the melting temperature were then determined by DSC measurement (differential scanning calorimetry) at a heating rate of 10 ° C./min. Pretreatment and measurement were carried out under nitrogen blanketing. The birefringence of the filament (Δn) was determined using a polarizing microscope with a tilt compensator and green filter (540 nm) using wedge cuts. The path difference between the ordinary and the extraordinary beam when linearly polarized light passed through the filament was measured. The birefringence is the quotient of the path difference and the filament diameter. In the spinning stretching process, the spun thread was removed after the take-off godet.

The strength properties of the fibers were determined on threads to which a twist of 50 T / m was applied, on a test length of 250 mm with a take-off speed of 200 mm / min. The force, which corresponds to a strain of 5% in the force-strain diagram divided by the titer, is referred to as LASE-5.

The hot air shrinkage was determined with the shrinkage tester from Testrite / USA at 160 ° C., a pretensioning force of 0.05 cN / dtex and a treatment time of 2 min.

The invention is explained in more detail below with the aid of examples:

Comparative Examples 1 to 3 and Examples 4 to 8:

A polyethylene terephthalate with an intrinsic viscosity of 0.98 dl / g was used to produce the HMLS yarn. A copolymer of 90% by weight of methyl methacrylate and 10% by weight of styrene, which had a glass transition temperature of 118.7 ° C., was chosen as the additive for Examples 4 to 7. In Example 8, a copolymer of 78% by weight of styrene and 22% by weight of imidized maleic anhydride with a glass transition temperature of 168 ° C. was used as an additive. The Polyester chips and the additive polymer were melted in a 7E extruder from Barmag, DE. The additive was dosed into the filler 1 piece of the extruder. The dosing system, type KCLKQX2, from K-Tron Soda, DE, was used for this with a gravitationally operating dosing control. The one melted and premixed in the extruder

The polymer mixture was forced through static mixers at 160 bar and fed to a 40 cm ³ melt metering pump. The mixture was subjected to a shear rate of 23 sec ^"1. The product of the shear rate and the 0.8th power of the residence time in seconds was 475. The spinning pump conveyed the melt, which was heated to 298 ° C., into the Lurgi Zimmer spinning system BN 110 with a round spinneret package and ring nozzle (300 holes with a diameter of 0.4 mm). The melt throughput was 660 g / min at all settings. This corresponds to a titer of 1100 dtex at a winding speed of 6000 m / min. The nozzle pressure was 420 bar. The spun multifilament thread was cooled in a radial blowing system (outside to inside), applied with a ring oiler with spinning preparation and fed to a 1st unheated godet duo. The speed of this 1st duo is by agreement equal to the spinning take-off speed. Only for sampling for the determination of birefringence was the spinning thread already after this 1. Duo fed to a take-up unit. To produce the HMLS thread, de r After the first duo, the thread is guided over 3 further heated godet duos and finally wound up. Stretching took place between the 1st and 3rd duo, heat-setting on the 3rd duo and between the 3. Duo and the winder the relaxation. The three heated duos had the following temperatures:

Duo 2: 85 ° C

Duo 3: 240 ° C

Duo 4: 150 ° C

The partial relaxation ratio between Duo 4 and Duo 3 was 0.995 in all cases. The other settings can be found in the table. The process parameters for the spinning process were identical in all examples. Based on the specified spinning speed and a desired birefringence, the range of additive polymer concentration to be used was calculated in accordance with equation 1, the factor x, depending on the additive, being used as 1 for Examples 3 to 7 and as 2.8 for Example 8. The actual concentration was chosen within the calculated range.

The respective preferred range for the draw ratio was calculated according to equation 4 and the actual draw ratio within the calculated range was selected. The drawing of the filaments could be carried out successfully in all examples according to the invention. Capillary breaks have rarely been observed. The individual values are summarized in the table below.

The examples make it clear that the concentration of the additive polymer can be determined according to equation (1) according to the invention in such a way that the desired birefringence can be achieved at a given spinning speed. In particular, the choice of additive concentration according to the invention does not exceed the maximum value of the desired birefringence. As a result, relatively high spinning speeds can be set without this leading to a reduction in strength or to an excessive number of fiber defects leads, as is the case with the known methods disadvantageously.

In all of the examples according to the invention, the mean diameter of the fibrils in the threads was below 80 nm.

Table:

Claims

claims

1. HMLS threads made of polyester with a tensile strength of> 70 cN / tex, a LÄSE 5 of> 35 cN / tex and a hot air shrinkage at 160 ° C of 1.5 - 3.5%, characterized in that they are made of

) a polyester which contains at least 85 mol% poly (C _2, _4- alylene) terephthalate,

β) 0.1 to 2.5% by weight of an incompatible, thermoplastically processable, amorphous, polymeric additive, which has a glass transition temperature in the range from 90 to 170 ° C., and

γ) 0 to 5.0% by weight of conventional additives,

exist, the sum of α), ß) and γ) being 100%, the ratio of the melt viscosity of the polymeric additive ß) to the melt viscosity of the polyester α) is 1: 1 to 7: 1, and the polymeric additive ß) in the HMLS threads are in the form of fibrils with an average diameter of <80 nm distributed in the polyester α).

2. HMLS threads according to claim 1, characterized in that the ratio of the melt viscosities is 1.5: 1 to 5: 1.

3. HMLS threads, according to claims 1 or 2, characterized in that the polymeric additive β) is a polymer which contains the following monomer units: A = acrylic acid, methacrylic acid or CH ₂ = CR - COOR ¹ , where R is an H atom or a CH ₃ group and R 'is a C ^^ - alkyl radical or a C ₅ _ ₁₂ cycloalkyl radical or a C ₅ . ₁₄ -alkyl radical,

B styrene or C 1-4 alkyl-substituted styrenes,

wherein the polymer consists of 60 to 100 wt .-% A and 0 to 40 wt .-% B, (sum = 100 wt .-%).

4. HMLS threads according to claim 3, characterized in that the

Polymer consists of 83 to 98% by weight of A and 2 to 17% by weight of B (total = 100% by weight).

5. HMLS threads according to claim 3 or 4, characterized in that the polymer from 90 to 98 wt .-% A and 2 to 10 wt .-% B (sum =

100% by weight).

6. HMLS threads according to claims 1 or 2, characterized in that the polymeric additive β) is a polymer which contains the following monomer units:

C = styrene or C ^ -alkyl substituted styrenes,

D = one or more monomers of the formula I, II or III

R - C = C - R ₂ R - C - COOH Rf - C - C = 0

1 1 II II) oo = c _{χ 7} c = o R— C— COOH R— C— C = 0

N

1 (i) (II) (III)

R ₃ where R_, R ₂ and R _{3 are} each an H atom or a C ^^ - alkyl radical or a C ₅ . ₁₂ -cycloalkyl radical or a C _6-14 aryl radical, and wherein the polymer consists of 15 to 100% by weight of C and 0 to 85% by weight of D, the sum of C and D together making 100%.

7. HMLS threads according to claim 6, characterized in that the polymer consists of 50 to 95% by weight of C and 5 to 50% by weight of D, the sum of C and D totaling 100%.

8. HMLS threads according to claims 6 or 7, characterized in that the polymer consists of 70 to 85 wt .-% C and 30 to 15 wt .-% D, the sum of C and D together making 100%.

9. HMLS threads according to claims 1 or 2, characterized in that the polymeric additive β) is a polymer which contains the following monomer units:

E = acrylic acid, methacrylic acid or CH ₂ = CR - COOR ', where R is an H atom or a CH ₃ group and R' is a C ^^ alkyl radical or a C _5-12 cycloalkyl radical or a C ₆ . ₁₄ aryl radical,

F = styrene or C ₁ _ ₃ -alkyl substituted styrenes,

G = one or more monomers of the formula I, II or III

R-C = C-R ₂ R-C-COOH R-C-C = 0

I I II II) o

0 = C _/ C = 0 R — C — COOH R —C — C = 0 NI (I) (II) (III)

R ₃ wherein R _ls R ₂ and R ₃ are each an H atom or a C ^ s alkyl radical or a C. ₅ ₁₂ -cycloalkyl radical or a C ₆ . ₁₄ - aryl radical,

H one or more ethylenically unsaturated with E and / or with F and / or G copolymerizable monomers from the group consisting of α-methyl styrene, vinyl acetate, acrylic acid esters, methacrylic acid esters, which are different from E, vinyl chloride, vinyl idene chloride, halogen-substituted Styrenes, vinyl ethers,

Isopropenyl ethers and dienes,

wherein the polymer consists of 30 to 99% by weight of E, 0 to 50% by weight of F,> 0 to 50% by weight of G and 0 to 50% by weight of H, the sum of E, F, G and H together make 100%.

10. HMLS threads according to claim 9, characterized in that the polymer from 45 to 97 wt .-% E, 0 to 30 wt .-% F, 3 to 40 wt .-% G and 0 to 30 wt .-% H exists, the sum of E, F, G and H together making 100%.

11. HMLS threads according to claim 9 or 10, characterized in that the polymer from 60 to 94 wt .-% E, 0 to 20 wt .-% F, 6 to

30 wt .-% G and 0 to 20 wt .-% H, the sum of E, F, G and H together making 100%.

12. Spin-stretching process for producing the HMLS threads according to one of claims 1-11, characterized in that a) a polyester α) which contains at least 85 mol% poly (C _2-4 alkylene) terephthalate, and

an incompatible, thermoplastically processable, amorphous polymeric additive β) which has a glass transition temperature in the range from 90 to 170 ° C., the ratio of the melt viscosity of the polymeric additive β) to the melt viscosity of the polyester component α) being 1: 1 to 7: 1 .

where these can contain 0 to 5.0% by weight of conventional additives γ),

are mixed in the molten state in a static mixer under shear, the shear rate being 16 to 128 sec ^"1 , and the product of the shear rate and the 0.8th power of the residence time in seconds in the mixer is set to a value of at least 250;

b) the melt mixture from stage a) is spun into filaments, the spinning take-off speed being 2500 to 4000 m / min; and

c) the filaments from stage b) are prepared, drawn, heat-set and wound up,

the concentration c of the polymeric additive β in% by weight in

Polyester is determined as a function of the specified take-off speed v in m / min and the desired birefringence Δn of the filaments according to the formulas below: f _: <c <X (1) where

(2)

100 • (Δn _Q - Δπ) = Δ .n- ₀ (5.9391 • 10 ^" . ⁰ _s • v ² -: 6.3 ^ 763 • 10, • v + 193.1527) ⁽⁾

where Δn <Δn ₀

Δn ₀ = birefringence with the same spinning conditions as the spun thread made from polyester according to the invention without the addition of additives,

x = 1 for additive polymers of type 1 or 3,

x = 2.8 for additive polymers of type 2 (without acrylic compound).

13. Spin-drawing process according to claim 12, characterized in that in step c) the draw ratio DR as a function of Spinning speed v in m / min and the concentration c of the additive in% by weight is determined according to the following formulas:

f, <DR <f ₄ (4)

f, = -5 10 ^" 1.6 ^• 10 ^{" 4 •} v ^• c / x + 0.98 ^• c / x + 3.55 (5)

f ₄ = -5 ^• 10 ^{"4 •} v - 2.4 ^• 10 ^{" 4 •} v ^• c / x + 1.46 ^• c / x + 3.55 (6)

14. Spin-stretching method according to claim 13, characterized in that in stage c) the winding speed is equal to the product of the spinning speed v, the stretching ratio DR and the relaxation ratio.