EP0735166A2 - High resistance core-sheath monofilaments for technical applications - Google Patents

Abstract

Core-sheath monofilaments with the following structure :(A) a (co)polyester (X) core with m.pt. 165-290 (220-240) degrees C and comprising ≥ 70 mol.% aromatic dicarboxylic acids (C) and aliphatic diols (D) (w.r.t. all polyester units) and NOTGREATER 30 mol.% other dicarboxylic acids (C1), arylaliphatic dicarboxylic acids (C2) with NOTLESS 1 (1-2) (non-)condensed aromatic rings or 4-12 (6-10) C acyclic aliphatic dicarboxylic acids (C3) and other aliphatic diols (D1), 3-10 (3-6) C branched and/or long chain diols (D2), cyclic diols (D3), ether diols (D4) or even a v. small amt. of polyglycol (D5) having mol. wt. 500-2000 ; and (B) a sheath comprising a thermoplastic polyester (Y) with m.pt. 165-240 (220-240) degrees C, thermoplastic elastomer PU (Z) and opt. standard non-polymer additives. Also claimed are: (i) prepn. of the yarns; (ii) high mechanical and chemical resistance textiles, paper machine wires, spiral fabrics, screen printing blankets, industrial filter cloths and conveyor belts contg. these yarns; and (iii) use of the yarns for making these textile prods.

Description

The present invention relates to heavy-duty core / sheath monofilaments for technical applications with high dimensional stability and abrasion resistance and very good heat and hydrolysis resistance as well as technical products made therefrom, in particular paper machine screens, fabrics for screen printing and for technical filter materials. The core / sheath monofilaments according to the invention have a polyester core and a sheath made from a mixture of a thermoplastic polyester and a thermoplastic elastomeric polyurethane.

In most cases, monofilaments for technical applications are subject to high mechanical loads. In addition, there are in many cases thermal and chemical and other environmental influences, to which the material has to provide sufficient resistance. With all these loads, the material must have good dimensional stability and constant force-elongation properties over the longest possible periods of use.

An example of technical applications in which there is a combination of high mechanical, thermal and chemical stresses is the use of monofilaments in paper machine screens, in particular in the so-called Fourdrinier wire. This application requires a monofilament material with a high initial modulus and high tear strength, good knot and loop strength and high abrasion resistance in order to withstand the high loads and to ensure a sufficient service life of the sieve. In addition to these parameters, a high hydrolysis resistance of the monofilament is required in the dryer section of the paper machine.

Similar high demands are placed on the monofilament material when used in screen printing fabrics, which should have a long service life under constant load from the doctor blade working under high pressure, through the hydrolytic attack of aqueous dye doughs and under the influence of highly actinic light sources. This places particularly high demands on the dimensional stability of the screen printing fabric, so that it is possible to produce precisely fitting multicolor prints.

Presently, paper machine screens for the forming and dryer sections are predominantly made from polyethylene terephthalate monofilaments in the warp and weft.
These screens have the disadvantage that they lengthen (lengthen) in the running direction during the course of the screen life on the paper machine and therefore retensioning must take place.

Screen printing fabrics are nowadays made from relatively fine titre monofilaments made of polyethylene terephthalate or polyamide in warp and weft.
The main disadvantage of the polyamide screens is their high water absorption, which has a negative effect on the elasticity, to which very high demands have to be made for screen printing fabrics; with polyester screens, their inherently poorer elastic behavior interferes. As a result, only relatively short service lives are achieved with such known screens.

Since then there has been no shortage of attempts to produce synthetic monofilament materials which are suitable for durable paper machine screens and screen printing fabrics. However, the demands placed on these technical products are so diverse that so far only partial solutions have been achieved in this area. It is known to use monofilaments made of polyphenylene sulfides for the production of paper machine screens. This material has a very good mechanical resistance with excellent hydrolysis stability. In contrast, it has an extremely low resistance to actinic radiation, so that such Monofilament material is completely unsuitable for the production of screen printing fabrics. The goal of producing monofilaments with this polymer, which can be used in both technical fields, could therefore not be achieved.
From Japanese Patent Laid-Open No. 45741 (1991) it is known to produce screen printing fabrics from polyethylene naphthalate monofilaments which, because of their higher modulus of elasticity (initial modulus), are said to be less susceptible to sagging. However, these filaments show a noticeable tendency to fibrillate when woven.
From Japanese Patent Laid-Open No. 5209 (1993), core / sheath monofilaments are known which are to be used for the production of screen printing fabrics. The core of these filaments consists of polyethylene-2,6-naphthalate, the sheath of polyethylene terephthalate or modified polyethylene terephthalate. To modify the jacket polyester, it can contain, for example, isophthalic acid, adipic acid or sebacic acid residues or longer-chain diol residues such as diglycol, butanediol or polyethylene glycol residues, where the polyethylene glycol residues can have a molecular weight of approximately 600 to 1500. According to the exemplary embodiment, the shell polyester can be, for example, a polyethylene terephthalate which is modified with 8% by weight of polyethylene glycol residues. Although this amount of modifier is sufficient to influence the strength properties and the melting behavior, it does not impart any elastomeric properties to the polyester.

It is also known that it is possible to produce polyester fibers with very different mechanical and textile properties. In particular, it is possible to produce monofilaments from polyethylene terephthalate by varying the spinning and drawing and relaxation conditions, which cover a broad spectrum of the properties relevant for technical monofilaments.

Efforts to obtain a monofilament material which at the same time has the high dimensional stability, abrasion resistance and hydrolysis resistance required for paper machine screens with the high resistance to However, combining actinic light, which is required for the production of screen printing fabrics, has so far not led to complete success.

In the effort to find a polyester fiber suitable for as many technical applications as possible, there has been no lack of attempts to replace polyethylene terephthalate with other polyester building blocks and with copolyesters. As alternative polyesters have already been investigated, for example, polyethylene naphthalate and copolyester from 4,4'-biphenyl-dicarboxylic acid and 2,6-naphthalene-dicarboxylic acid, as described, for. B. have been described in European Patent Application No. 202,631.
Fibers made from 4,4'-biphenyl-dicarboxylic acid and 2,6-naphthalene-dicarboxylic acid have already been proposed in WO 93/02122. These fibers have a high longitudinal strength and a high modulus if they are spun with a high spinning delay without further post-stretching. The applicability of this material for the production of monofilaments, especially for the manufacture of paper machine screens and screen printing fabrics, had to be doubted, however, since experience has shown that a high modulus usually goes hand in hand with a low transverse strength.

A copolyester of 4,4'-biphenyl-dicarboxylic acid and 2,6-naphthalene-dicarboxylic acid and ethylene glycol, which is said to be suitable for the production of tire cord, has been described in Japanese Patent Application 50-135,333. This publication shows that such a copolyester must not contain more than 20 mol% of 4,4'-biphenyl-dicarboxylic acid, because otherwise its initial modulus and softening temperature will drop too much. This statement is supported in this document by examples in which it is shown that the softening temperature, which is 275 ° C. for pure polyethylene naphthalate, drops to 238 ° C. for a copolyester with about 25 mol% of 4,4'-biphenyl-dicarboxylic acid .
It is also known that polymers from 4,4'-biphenyl-dicarboxylic acid crystallize extremely quickly. For this reason too, the manufacturability of monofilaments using this raw material had to be questioned are too rapid crystallization leads to early embrittlement of the monofilaments during the manufacturing process, with the result that they tear off before sufficient orientation is achieved.
In German patent application P-43 28 029.3 it has also already been proposed to produce monofilaments essentially from a mixture of polyethylene-2,6-naphthalate and polyethylene-biphenylene-4,4'-dicarboxylate.
Another proposal for the production of paper machine screens can be found in German patent application P-44 10 399.9. According to this proposal, the screens are to be woven from monofilaments spun from an abrasion-resistant polyester blend consisting of a blend of a thermoplastic polyester and a thermoplastic polyurethane. This patent application does not refer to the use of core / sheath monofilaments.

It has now surprisingly been found that it is possible to produce monofilaments which have a combination of further improved mechanical properties relevant to application, high stability against actinic radiation and high chemical stability, in particular hydrolysis stability, and which are therefore accessible to an expanded range of technical applications. These monofilaments essentially consist of polyesters - the term "polyester" in the sense of the present invention also includes copolyesters - and have a core / shell structure.

The present invention thus relates to monofilaments with a core / sheath structure with a core made of a thermoplastic polyester or copolyester and a sheath containing a thermoplastic polyester, which are characterized in that the polyester or copolyester of the core has a melting point of 165 to 290 ° C, preferably from 220 to 240 ° C, and
at least 70 mol%, based on the totality of all polyester assemblies, from assemblies that differ from aromatic Dicarboxylic acids and derived from aliphatic diols, and
to a maximum of 30 mol%, based on the totality of all polyester assemblies, from dicarboxylic acid assemblies which are different from the aromatic dicarboxylic acid assemblies which form the majority of the dicarboxylic acid assemblies, or from araliphatic dicarboxylic acids with one or more, preferably one or two condensed or uncondensed aromatic nuclei, or derived from cyclic or acyclic aliphatic dicarboxylic acids with a total of 4 to 12 carbon atoms, preferably 6 to 10 carbon atoms
and diol assemblies which are derived from aliphatic diols and are different from the diol assemblies which form the majority of the diol assemblies, or which are branched and / or longer-chain diols having 3 to 10, preferably 3 to 6 , Carbon atoms, or from cyclic diols, or from ether-containing diols, or, if present in small amounts, from polyglycol with a molecular weight of approx. 500 - 2000,
and the jacket consists of a polyester mixture of a thermoplastic polyester, the melting point of which is between 165 and 240 ° C., preferably 220 and 240 ° C., and a thermoplastic, elastomeric polyurethane and, if appropriate, customary non-polymeric additives.

The proportion of the sheath in the total cross-sectional area of the monofilament is 5 to 95%, preferably 10 to 60, in particular 15 to 35%, the proportion of the core 5 to 95%, preferably 40 to 90, in particular 65 to 85%.

• 35 bis 50 Mol-% Baugruppen der Formel -CO-A¹-CO-   (I)
• 0 bis 15 Mol-% Baugruppen der Formel -CO-A²-CO-   (II)
• 35 bis 50 Mol-% Baugruppen der Formel -O-D¹-O-   (III)
• 0 bis 15 Mol-% Baugruppen der Formel -O-D²-O-   (IV)
  und
• 0 bis 25 Mol.-% Baugruppen der Formel -O-A³-CO-   (V)
  worin
  • A¹ aromatische Reste mit 5 bis 12, vorzugsweise 6 bis 10 C-Atomen
  • A² von A¹ verschiedene aromatische Reste oder araliphatische Reste mit 5 bis 16, vorzugsweise 6 bis 12 C-Atomen oder cyclische oder acyclische aliphatische Reste mit 2 bis 10 Kohlenstoffatomen, vorzugsweise 4 bis 8 Kohlenstoffatomen,
  • A³ aromatische Reste mit 5 bis 12, vorzugsweise 6 bis 10 C-Atomen
  • D¹ Alkylen- oder Polymethylengruppen mit 2 bis 4 Kohlenstoffatomen oder Cycloalkan- oder Dimethylen-cycloalkangruppen mit 6 bis 10 C-Atomen,
  • D² von D¹ verschiedene Alkylen- oder Polymethylengruppen mit 3 bis 4 Kohlenstoffatomen oder Cycloalkan- oder Dimethylen-cycloalkangruppen mit 6 bis 10 C-Atomen oder geradkettige oder verzweigte Alkandiyl-Gruppen mit 4 bis 16, vorzugsweise 4 bis 8, C-Atomen oder Reste der Formel -(C₂H₄-O)_m-C₂H₄-, worin m eine ganze Zahl von 1 bis 40 bedeutet, wobei m = 1 oder 2 für Anteile bis zu 20 Mol.-% bevorzugt sind und Gruppen mit m = 10 bis 40 vorzugsweise nur in Anteilen von unter 5 Mol.-% vorhanden sind, bedeuten.

The polyester of the core, based on the totality of all polyester assemblies, preferably consists of

• 35 to 50 mol% of assemblies of the formula -CO-A ¹ -CO- (I)
• 0 to 15 mol% of assemblies of the formula -CO-A ² -CO- (II)
• 35 to 50 mol% of assemblies of the formula -OD ¹ -O- (III)
• 0 to 15 mol% of assemblies of the formula -OD ² -O- (IV)
  and
• 0 to 25 mol% of assemblies of the formula -OA ³ -CO- (V)
  wherein
  • A ¹ aromatic radicals having 5 to 12, preferably 6 to 10 carbon atoms
  • A ² different from A ¹ aromatic radicals or araliphatic radicals having 5 to 16, preferably 6 to 12 C atoms or cyclic or acyclic aliphatic radicals having 2 to 10 carbon atoms, preferably 4 to 8 carbon atoms,
  • A ³ aromatic radicals with 5 to 12, preferably 6 to 10 carbon atoms
  • D ¹ alkylene or polymethylene groups with 2 to 4 carbon atoms or cycloalkane or dimethylene-cycloalkane groups with 6 to 10 C atoms,
  • D ² D ¹ different from alkylene or polymethylene groups with 3 to 4 carbon atoms or cycloalkane or dimethylene cycloalkane groups with 6 to 10 carbon atoms or straight-chain or branched alkanediyl groups with 4 to 16, preferably 4 to 8, carbon atoms or Residues of the formula - (C ₂ H ₄ -O) _m -C ₂ H ₄ -, in which m is an integer from 1 to 40, where m = 1 or 2 are preferred for proportions up to 20 mol% and groups with m = 10 to 40 are preferably present only in proportions of less than 5 mol%.

In a preferred core polyester, the symbols A ¹ in the assemblies I and III denote 1,4-phenylene and D ¹ ethylene, and in this polyester the assemblies I and III preferably make up at least 85 mol%, in particular at least 90 mol%. % of all assemblies.
In a further preferred core polyester in the assemblies I and III of the polyester of the core A ^{1 is} 2,6-naphthylene and D ^{1 is} ethylene, and in this polyester too the assemblies I and III preferably make up at least 85 mol%, in particular at least 90 mol% of all assemblies.

und Biphenyl-1,4-diyl der Formel VII

und D¹ Ethylen, wobei wiederum besonders bevorzugt solche sind, in denen die Baugruppen I und III mindestens 85 Mol.-%, insbesondere mindestens 90 Mol.-%, aller Baugruppen ausmachen.
Weiterhin ist es dabei besonders vorteilhaft, wenn die für A¹ stehenden Gruppen 2,6-Naphthylen und Biphenyl-1,4-diyl im Molverhälnis von maximal 3:1, vorzugsweise im Molverhältnis zwischen 6:4 und 4:6 vorhanden sind.In a further preferred embodiment of the present invention in the assemblies I and III of the core polyester, the symbols A ^{1 represent} 2,6-naphthylene of the formula VI

and biphenyl-1,4-diyl of formula VII

and D ¹ ethylene, again particularly preferred being those in which the assemblies I and III make up at least 85 mol%, in particular at least 90 mol%, of all assemblies.
Furthermore, it is particularly advantageous if the standing for A ¹ groups 2,6-naphthylene and biphenyl-1,4-diyl in the mole ratio of maximum 3: 1, preferably in a molar ratio between 6: there are 6: 4 and 4. FIG.

Core polyesters are also preferred in which the symbols A ¹ in the assemblies I and III mean 1,4-phenylene and D ¹ 1,4-bismethylene-cyclohexane, and in particular those in which the assemblies I and III have at least 85 mol. %, in particular at least 90 mol%, of all assemblies.

The polyester of the core expediently has a specific viscosity of 0.55 to 1.6, preferably 0.58 to 1.5, measured in a 1% strength by weight solution of the polyester in dichloroacetic acid at 25 ° C.

The polyesters of different chemical compositions can have different specific viscosities with the same average molecular weight and / or with the same spinnability and / or filament strength. For example, the specific viscosities of polyesters, which are essentially based on polyethylene naphthalate and which provide good filaments, are in the range from 0.55 to 0.8. For polyethylene terephthalate and its copolyesters the range is from 0.7 to 1.0, for poly (1,4-bismethylolcyclohexane) terephthalate and its modifications the range is from 1.15 to 1.5, for polybutylene terephthalate and its modifications the range is from 1.1 to 1.3 particularly useful. “Its modifications” are understood to mean those polyesters which, in addition to the main components mentioned, contain up to 15 mol% of the above-mentioned modifying components in the molecule.

The polymer material of the polyester mixture of the jacket consists of 1 to 99% by weight, preferably 30 to 90% by weight, in particular 50 to 80% by weight, of the thermoplastic polyester and 1 to 99% by weight, preferably 10 to 70 wt .-%, in particular 20 to 50 wt .-% of the thermoplastic polyurethane.
It is surprising here that very small additions of the elastomeric, thermoplastic polyurethane bring about significant improvements in the application properties. It is therefore often sufficient to work with the smallest additional amounts in the range given above. This results in a price advantage for the monofilament according to the invention, since the elastomer additives are relatively expensive materials.
In addition, of course, the addition of elastomer is measured in the context of the above quantities according to the requirements of the individual application.

The polyester of the polyester mixture of the jacket preferably has a glass point in the range from 60 to 120 ° C., in particular from 70 to 85 ° C., a crystallization point in the range from 135 to 155 ° C., in particular from 140 to 150 ° C., and a melting point in Range from 165 ° C to 240 ° C, especially from 220 to 240 ° C.

The polyester of the polyester mixture of the sheath expediently has a melt viscosity, measured at 245 ± 2 ° C. and a shear rate of 200 ± 5 s ^-1 from 445 to 482 Pa · s, preferably from 455 to 475 Pa · s, in particular from 460 to 468 Pa · s and at the same temperature and a shear rate of 1200 ± 5 s ^-1 from 245 to 282 Pa · s, preferably from 250 to 272, in particular from 255 to 270 Pa · s.

The polyester of the polyester mixture of the sheath consists of at least 70 mol%, based on the totality of all polyester assemblies, of assemblies which are derived from aromatic dicarboxylic acids and aliphatic diols, and a maximum of 30 mol%, based on the totality of all polyester assemblies, from dicarboxylic acid components which differ from the aromatic dicarboxylic acid components which form the majority of the dicarboxylic acid components, or from araliphatic dicarboxylic acids with one or more, preferably one or two condensed or uncondensed aromatic nuclei, or from cyclic ones or acyclic aliphatic dicarboxylic acids with a total of 4 to 12 carbon atoms, preferably 6 to 10 carbon atoms
and diol assemblies which are derived from aliphatic diols and are different from the diol assemblies which form the majority of the diol assemblies, or which are branched and / or longer-chain diols having 3 to 10, preferably 3 to 6 , Carbon atoms, or from cyclic diols, or from ether-containing diols, or, if present in small amounts, from polyglycol with a molecular weight of about 500-2000.

• 35 bis 50 Mol-% Baugruppen der Formel -CO-A¹-CO-   (I)
• 0 bis 15 Mol-% Baugruppen der Formel -CO-A²-CO-   (II)
• 35 bis 50 Mol-% Baugruppen der Formel -O-D¹-O-   (III)
• 0 bis 15 Mol-% Baugruppen der Formel -O-D²-O-   (IV)
  und
• 0 bis 25 Mol.-% Baugruppen der Formel -O-A³-CO-   (V)
  aufgebaut ist, worin
  • A¹ aromatische Reste mit 5 bis 12, vorzugsweise 6 bis 10 C-Atomen
  • A² von A¹ verschiedene aromatische Reste oder araliphatische Reste mit 5 bis 16, vorzugsweise 6 bis 12 C-Atomen oder cyclische oder acyclische aliphatische Reste mit 2 bis 10 Kohlenstoffatomen, vorzugsweise 4 bis 8 Kohlenstoffatomen,
  • A³ aromatische Reste mit 5 bis 12, vorzugsweise 6 bis 10 C-Atomen,
  • D¹ Alkylen- oder Polymethylengruppen mit 2 bis 4 Kohlenstoffatomen oder Cycloalkan- oder Dimethylen-cycloaikangruppen mit 6 bis 10 C-Atomen,
  • D² von D¹ verschiedene Alkylen- oder Polymethylengruppen mit 3 bis 4 Kohlenstoffatomen oder Cycloalkan- oder Dimethylen-cycloalkangruppen mit 6 bis 10 C-Atomen oder geradkettige oder verzweigte Alkandiyl-Gruppen mit 4 bis 16, vorzugsweise 4 bis 8, C-Atomen oder Reste der Formel -(C₂H₄-O)_m-C₂H₄-, worin m eine ganze Zahl von 1 bis 40 bedeutet, wobei m = 1 oder 2 für Anteile bis zu 20 Mol.-% bevorzugt sind und Gruppen mit m = 10 bis 40 vorzugsweise nur in Anteilen von unter 5 Mol.-% vorhanden sind, bedeuten.

The polyester preferably consists of the polyester mixture of the jacket, based on the entirety of all polyester assemblies

• 35 to 50 mol% of assemblies of the formula -CO-A ¹ -CO- (I)
• 0 to 15 mol% of assemblies of the formula -CO-A ² -CO- (II)
• 35 to 50 mol% of assemblies of the formula -OD ¹ -O- (III)
• 0 to 15 mol% of assemblies of the formula -OD ² -O- (IV)
  and
• 0 to 25 mol% of assemblies of the formula -OA ³ -CO- (V)
  is built up in what
  • A ¹ aromatic radicals having 5 to 12, preferably 6 to 10 carbon atoms
  • A ² different from A ¹ aromatic radicals or araliphatic radicals having 5 to 16, preferably 6 to 12 C atoms or cyclic or acyclic aliphatic radicals having 2 to 10 carbon atoms, preferably 4 to 8 carbon atoms,
  • A ³ aromatic radicals having 5 to 12, preferably 6 to 10, carbon atoms,
  • D ¹ alkylene or polymethylene groups with 2 to 4 carbon atoms or cycloalkane or dimethylene-cycloaikane groups with 6 to 10 C atoms,
  • D ² D ¹ different from alkylene or polymethylene groups with 3 to 4 carbon atoms or cycloalkane or dimethylene cycloalkane groups with 6 to 10 carbon atoms or straight-chain or branched alkanediyl groups with 4 to 16, preferably 4 to 8, carbon atoms or Residues of the formula - (C ₂ H ₄ -O) _m -C ₂ H ₄ -, in which m is an integer from 1 to 40, where m = 1 or 2 are preferred for proportions up to 20 mol% and groups with m = 10 to 40 are preferably present only in proportions of less than 5 mol%.

It is particularly preferred that in assemblies I and III of the polyester of the polyester mixture of the jacket A ^{1 is} 1,4-phenylene and 1,3-phenylene and D ^{1 is} ethylene, the molar ratio of 1,4- and 1,3- Phenylene is chosen so that the polyester has a melting point in the range of 220 to 240 ° C.

It is further preferred if the polyester contained in the polyester mixture of the jacket also has a specific viscosity of 0.55 to 1.6, preferably 0.58 to 1.5, measured in a 1% by weight solution of the polyester in Dichloroacetic acid at 25 ° C, and / or if both the polyester of the core and the polyester contained in the polyester mixture of the jacket has a melting point between 220 to 240 ° C.

It is also particularly important with regard to core / shell adhesion preferred that the polyester of the core and the polyester of the polyester mixture of the jacket have the same chemical composition.

For the chemical stability, in particular against hydrolysis, of the monofilaments according to the invention, it is particularly advantageous if the polyester of the core and the polyester of the polyester mixture of the sheath do not contain more than 60 meq / kg, preferably less than 30 meq / kg, blocked carboxyl groups and less than 5 mVal / kg, preferably less than 2 mVal / kg, in particular less than 1.5 mVal / kg, has free carboxyl end groups.
The polyester of the core and the polyester of the polyester mixture of the jacket therefore preferably have end-capped carboxyl groups, for example by reaction with mono-, bis- and / or polycarbodiimides.
In a further embodiment, which is preferred with regard to a hydrolysis stability that also lasts for longer periods, the polyester of the core and the polyester of the polyester mixture of the jacket have a maximum of 200 ppm, preferably a maximum of 50 ppm, in particular 0 to 20 ppm, mono- and / or biscarbodiimides and 0.02 to 0.6% by weight, preferably 0.05 to 0.5% by weight, of free polycarbodiimide with an average molecular weight of 2,000 to 15,000, preferably of 5,000 to 10,000. Suitable carbodiimide-based hydrolysis stabilizers are, for example, the ®Stabaxol types from Bayer AG.

The core / sheath monofilaments according to the invention, which consist of the polyesters described above, in particular of polyethylene terephthalate, are not easy to ignite.

worin R Alkylen oder Polymethylen mit 2 bis 6 C-Atomen oder Phenyl und R¹ Alkyl mit 1 bis 6 C-Atomen, Aryl oder Aralkyl bedeutet, einkondensiert enthalten.
Vorzugsweise bedeuten in der Formel VIII R Ethylen und R¹ Methyl, Ethyl, Phenyl, oder o-, m- oder p-Methyl-phenyl, insbesondere Methyl.
Die Baugruppen der Formel VIII sind zweckmäßigerweise in der Polyesterkette zu bis zu 15 Mol%, vorzugsweise zu 1 bis 10 Mol%, enthalten.
Ein zur Einführung einer Gruppe der Formel VIII geeignetes Mittel ist das Handelsprodukt ®Phospholan der Fa. Hoechst AG.Flame retardancy can be increased by using flame retardant modified polyesters. Such flame-retardant modified polyesters are known. They contain additives of halogen compounds, in particular bromine compounds, or, which is particularly advantageous, they contain phosphorus compounds which are incorporated in the polyester chain are condensed. Particularly preferred, flame-retardant pile goods according to the invention contain, in the back and / or pile, yarns made of polyesters which in the chain contain assemblies of the formula VIII

wherein R is alkylene or polymethylene with 2 to 6 carbon atoms or phenyl and R ^{1 is} alkyl with 1 to 6 carbon atoms, aryl or aralkyl, contained in condensed form.
In the formula VIII, R preferably denotes ethylene and R ¹ denotes methyl, ethyl, phenyl, or o-, m- or p-methylphenyl, in particular methyl.
The components of the formula VIII are expediently contained in the polyester chain up to 15 mol%, preferably 1 to 10 mol%.
A suitable means for introducing a group of formula VIII is the commercial product ®Phospholan from Hoechst AG.

Depending on the desired properties, the aromatic rings of the polyester of the core and of the polyester of the polyester mixture of the shell can be unsubstituted or can carry one or two non-reactive substituents. Suitable substituents are halogen atoms, preferably fluorine or chlorine, lower alkyl groups with up to 4 carbon atoms, such as. As methyl, ethyl, n-butyl isobutyl or tertiary butyl, preferably methyl, lower alkoxy groups with up to 4 carbon atoms, such as. B. methoxy, ethoxy or butoxy, preferably methoxy, or the sulfo group -SO ₃ H.

The elastomeric polyurethane of the polyester mixture of the jacket preferably has
a shear modulus which has a value in the temperature range from 20 to 60 ° C. of 8 to 80 MPa, preferably of 20 to 50 MPa,
a mechanical loss factor tan (δ), which is in the temperature range of 20 to 60 ° C has a value of 0.8 * 10 ^-2 to 1.2 * 10 ^-1 ,
a Shore hardness A, measured according to DIN 53505, from 82 to 100,
a Shore hardness D, measured according to DIN 53505, from 30 to 60
a tensile strength, measured according to DIN 53504, of 32 to 42 MPa
an elongation at break, measured according to DIN 53504, from 420 to 520%
and an impact strength, measured according to DIN 53515, from 32 to 45%.

   worin

• R¹ ein zweibindiger, aromatischer oder araliphatischer Rest mit 6 bis 18 C-Atomen mit einem ggf. substituierten aromatischen Ring oder mit zwei kondensierten oder nicht kondensierten, ggf. substituierten aromatischen Ringen ist,
• R² eine Polyetherbaugruppe der Formel X ist,
  
  worin
• X³ für Wasserstoff oder Methyl steht, und m eine Zahl von 10 bis 100, vorzugsweise von 10 bis 30 ist oder R² der Rest des Polytetrahydrofurans oder, vorzugsweise eine Baugruppe der Formel XI
  
• worin R³ geradkettiges oder ggf. verzweigtes Alkan-diyl oder Oxy-alkan-diyl mit 2 bis 8, vorzugsweise 2 bis 6 C-Atomen, wie z.B. Ethylen, Propan-1,3-diyl, Butan-1,4-diyl, Hexan-1,6-diyl, 2-Ethylhexan-1,6-diyl, 2,2-Dimethylpropan-1,3-diyl oder die von Di-ethylenglycol oder Triethylenglycol sich ableitenden zweiwertigen Oxaalkan-diyl-Reste,
• R⁴ Alkan-diyl mit 2 bis 6, vorzugsweise 2 bis 4 C-Atomen, Cycloalkan-diyl wie Cyclohexan-1,4 oder 1,3-diyl oder ein zweibindiger aromatischer Rest mit 6 bis 12 C-Atomen, vorzugsweise 6 bis 10 C-Atomen, insbesondere 1,3- oder 1,4-Phenylen,
• p eine Zahl ist die so gewählt ist, daß die Polyesterbaugruppe der Formel (XI) ein Molgewicht von 1000 bis 2000 hat (p = 5 bis 12, vorzugsweise 8 bis 11)
• und q entweder 0 oder 1 bedeutet.

The elastomeric polyurethane of the polyester mixture of the jacket preferably corresponds to the idealized formula IX,

wherein

• R ^{1 is} a double-bonded, aromatic or araliphatic radical having 6 to 18 carbon atoms with an optionally substituted aromatic ring or with two condensed or uncondensed, optionally substituted aromatic rings,
• R ^{2 is} a polyether assembly of the formula X,
  
  wherein
• X ^{3 represents} hydrogen or methyl, and m is a number from 10 to 100, preferably from 10 to 30 or R ^{2 is} the rest of the polytetrahydrofuran or, preferably an assembly of the formula XI
  
• wherein R ³ straight-chain or optionally branched alkane-diyl or oxy-alkane-diyl with 2 to 8, preferably 2 to 6 carbon atoms, such as ethylene, propane-1,3-diyl, butane-1,4-diyl, hexane-1,6-diyl, 2-ethylhexane-1,6-diyl , 2,2-dimethylpropane-1,3-diyl or the divalent oxaalkane-diyl radicals derived from diethylene glycol or triethylene glycol,
• R ⁴ alkane-diyl with 2 to 6, preferably 2 to 4 carbon atoms, cycloalkane-diyl such as cyclohexane-1,4 or 1,3-diyl or a divalent aromatic radical with 6 to 12 carbon atoms, preferably 6 to 10 Carbon atoms, in particular 1,3- or 1,4-phenylene,
• p is a number which is chosen such that the polyester assembly of the formula (XI) has a molecular weight of 1000 to 2000 (p = 5 to 12, preferably 8 to 11)
• and q means either 0 or 1.

• worin R¹ Phenylen, Naphthylen, oder eine Baugruppe der Formeln XII oder XIII ist,
  
• die ggf. Substituenten tragen können,
• worin X¹ ein zweibindiger aliphatischer Rest mit 1 bis 3 C-Atomen und X² eine direkte Bindung, ein zweibindiger aliphatischer Rest mit 1 bis 3 C-Atomen, -CO-, -SO₂- oder -NH-CO-NH- ist.

Alternatively, the elastomeric polyurethane of the polyester mixture of the jacket preferably corresponds to the idealized formula IX,

• wherein R ^{1 is} phenylene, naphthylene, or an assembly of the formulas XII or XIII,
  
• who may have substituents,
• wherein X ^{1 is} a divalent aliphatic radical with 1 to 3 C atoms and X ^{2 is} a direct bond, a divalent aliphatic radical with 1 to 3 C atoms, -CO-, -SO ₂ - or -NH-CO-NH- .

In a further alternative, the elastomeric polyurethane of the polyester mixture of the jacket preferably corresponds to the idealized formula VI, in which R ^{1 is} an assembly of the formula XIV.

The aromatic rings contained in an elastomeric polyurethane of the polyester mixture of the jacket, which corresponds to the idealized formula IX, can be unsubstituted to modify the polyurethane properties or can carry one or two substituents from the group -SO ₃ H or -CH ₃ .
A commercially available polyurethane which is suitable for the production of the polyester mixture of the sheath of the core / sheath monofilaments according to the invention is, for example, the product from Bayer AG available under the name ®Desmopan.

The monofilaments according to the invention expediently have a titer of 1 to 24400 dtex (in the case of a round cross section corresponding to filament diameters of 10 to 1500 μm) and a round, elliptical or n-angular cross-sectional shape, the ratio of the major axis to the minor axis being up to 10 in the case of an elliptical shape : 1 and n ≧ 4, preferably 4 to 8.

The core / sheath monofilaments according to the invention preferably also have the following features, which can be present individually or in combination: an initial modulus at 25 ° C. of more than 10, preferably more than 12 N / tex, a fineness-related maximum tensile force of more than 18 cN / tex , preferably from 20 to 45 cN / tex,
a dry heat shrinkage, measured at 180 ° C of over 0.5%, preferably from 1 to 25%.
The initial module in the sense of this invention is understood to mean the slope of the secant of the force-strain diagram between the points of 0.3% and 0.5% strain. Particularly characteristic initial moduli are in the range from 15 to 25 N / tex.

The maximum tensile force stretch is usually in the range of over 7%, preferably from 8 to 18%.

In addition to the copolyester described above, the monofilaments according to the invention may also contain small amounts of admixtures and additives of a non-polymeric nature, such as, for. B. catalyst residues, modification additives, fillers, matting agents, pigments, dyes, stabilizers, such as UV absorbers, antioxidants, hydrolysis, light and temperature stabilizers and / or processing aids, plasticizers or lubricants. These additives are usually present in a concentration of at most 10% by weight, preferably 0.01-5% by weight, in particular 0.1-2% by weight. The catalyst residues can be, for example, antimony trioxide or tetraalkoxy titanates. Processing aids or lubricants which can be used are siloxanes, in particular polymeric dialkyl- or diarylsiloxanes, salts and waxes and longer-chain organic carboxylic acids, that is to say those with more than 6 carbon atoms, aliphatic, aromatic and / or perfluorinated esters and ethers in amounts of up to 1% by weight become. The monofilaments can also contain inorganic or organic pigments or matting agents, such as. B. organic dye pigments or titanium dioxide, or carbon black as a color or conductivity additive. As stabilizers, for example, phosphorus compounds such. B. phosphoric acid esters, and in addition, if necessary, viscosity modifiers and substances for modifying the crystallite melting point or the glass transition temperature or those which influence the crystallization kinetics or the degree of crystallization can be used. As a viscosity modifier, for example, polyhydric carboxylic acids or their esters, such as trimesic or trimellitic acid, or polyhydric alcohols, such as. B. diethylene glycol, triethylene glycol, glycerin or pentaerytrite. These compounds are either added to the finished polymers in a small amount or, preferably, added as copolymerization constituents in the desired amount in the preparation of the polymers.

Special advantages for the technical application result if the polyester of the core and / or the polyester mixture of the sheath are colored differently.
The different coloring can be achieved in that the polyester of the core and / or the polyester mixture of the jacket contain different dyes or in that either the polyester of the core or the polyester mixture of the jacket
contain up to 5% by weight of one dye and the other filament component is natural in color.
The dye in the core and / or in the jacket of the monofilaments is expediently a dye or pigment soluble in polyester.
The different coloring of the core and sheath of the monofilaments according to the invention ensures that the monofilaments become discolored with a certain degree of wear.

Another object of the present invention is a process for producing the core / sheath monofilaments according to the invention described above, the thermoplastic polyester for the core and a polyester mixture for the sheath being melted separately in an extruder, and at melt temperatures of 185 to 320 ° C, preferably from 210 to 270 ° C, with a spinning delay of 1: 1.5 to 1: 5, preferably 1: 2 to 1: 3, spun, cooled in a spinning bath and wound up or drawn off, the spun thread thus produced is then subjected to post-drawing in the total drawing ratio of 1: 4 to 1: 8, and then heat setting at temperatures of 160 to 250 ° C, with constant length or with approval of 2 to 30% shrinkage.

In this process, a polyester or copolyester is used for the core, which has a melting point of 165 to 290 ° C, preferably from 220 to 240 ° C, and
at least 70 mol%, based on the totality of all Polyester assemblies, from assemblies derived from aromatic dicarboxylic acids and from aliphatic diols, and
to a maximum of 30 mol%, based on the totality of all polyester assemblies, from dicarboxylic acid assemblies which are different from the aromatic dicarboxylic acid assemblies which form the majority of the dicarboxylic acid assemblies, or from araliphatic dicarboxylic acids with one or more, preferably one or two condensed or uncondensed aromatic nuclei, or derived from cyclic or acyclic aliphatic dicarboxylic acids with a total of 4 to 12 carbon atoms, preferably 6 to 10 carbon atoms
and diol assemblies which are derived from aliphatic diols and are different from the diol assemblies which form the majority of the diol assemblies, or which are branched and / or longer-chain diols having 3 to 10, preferably 3 to 6 , Carbon atoms, or from cyclic diols, or from ether-containing diols, or, if present in small amounts, from polyglycol with a molecular weight of about 500-2000.
For the production of the jacket, a polyester mixture is used, which consists of a thermoplastic polyester, the melting point of which is between 165 and 240 ° C., preferably 220 and 240 ° C., and a thermoplastic, elastomeric polyurethane and, if appropriate, customary non-polymeric additives.

Spinning can be carried out using a special spinneret provided with a central opening and one or more peripheral jacket openings for the production of core / sheath filaments. The melts for core and shell are then filtered in a spin pack, the thermoplastic polyester is fed to the core opening and the abrasion-resistant polyester mixture to the shell opening of a spinneret for the production of core / shell monofilaments. In another, very advantageous embodiment of the method according to the invention, the core polyester is fed to the center and the polyester mixture for the jacket of the monofilament to the periphery of a spin pack and spun through a simple spinning opening. This technology has been described in detail in EP-A-0 434 448. It leads to core / shell monofilaments with particularly good core / shell adhesion.

Advantageously, the polymer components for the jacket - which may contain non-polymeric constituents present - are combined with one another in the desired quantity ratio immediately before the extruder inlet and the homogenization is carried out in the inlet and mixing area of the extruder screw.
To produce particularly hydrolysis-stable core / sheath monofilaments according to the invention, the polyesters of the core and the polyester mixture of the sheath are spun 1.0 to 1.2 times the amount which is equivalent to the amount of free carboxyl end groups contained therein, in mono -, Bis- and / or polycarbodiimides added.
It is of particular advantage for long-term stability if the polyesters of the core and the polyester mixture of the sheath, prior to spinning, contain an amount of at most 0.6% by weight of a mono- and / or biscarbodiimide and at least 0.05% by weight of one Polycarbodiimids added.

With this measure too, it is expedient for the mono-, bis- and / or polycarbodiimides to be added immediately before spinning, so that the contact time of molten polyester and carbodiimide additives is less than 5, preferably less than 3, minutes.
Spinning is preferably carried out at a melting temperature in the range from 210 to 250 ° C. and the monofilaments are drawn off at a spinning take-off speed of 5 to 30 m per minute.

The spinning temperature and the spinning delay, which can be determined by setting the injection speed and the spinning take-off speed, and the drawing conditions are chosen so that the monofilaments according to the invention have the following parameters:
An initial module at 25 ° C of greater than 10, preferably greater than 12 N / tex,
a fineness-related maximum tensile force of over 18, preferably from 20 to 45 cN / tex,
a maximum tensile elongation of more than 7, preferably from 8 to 18%, a dry heat shrinkage at 180 ° C. of> 0.5, preferably 1 to 25%.

The exact definition of the composition and spinning parameters to achieve a certain combination of monofilament properties can be routinely carried out by determining the dependence of the monofilament property under consideration on the composition of the polyester and on the spinning parameters mentioned.

The polyesters and copolyesters are produced by polycondensation of the corresponding dicarboxylic acid and diol components, it being expedient first to polycondense in the melt to an average IV value and then to condense further in the solid phase to the desired final viscosity. Dicarboxylic acid and diol components should expediently be present in approximately the same molar ratios. However, if it is expedient, for example to influence the reaction kinetics, one of the two components, preferably the diol, can also be used in excess. The excess of diol is then distilled off in the course of the polycondensation. The polycondensation is carried out by customary methods, for example by starting from 50 mol% of the corresponding dicarboxylic acids and / or dicarboxylic acid dialkyl esters, such as the carboxylic acid dimethyl or diethyl ester, and ≧ 50 mol% of the diol, which may initially be in In the presence of a transesterification catalyst, the mixture is heated to about 200 ° C. until sufficient methyl or ethyl alcohol has been distilled off, a low molecular weight oligo- or polyester being formed. This low molecular weight ester is then polycondensed in a molten state to a higher molecular weight polyester at a reaction temperature of approx. 240-290 ° C. in the presence of a polycondensation catalyst. This polycondensation is up to an IV of about 0.5 to 0.8 dl / g led. Catalysts which can be used here are the catalysts conventionally used for polycondensation, such as Lewis acids and bases, polyphosphoric acid, antimony trioxide, titanium tetraalkoxides, germanium tetraethoxide, organophosphates, organophosphites and mixtures thereof, a mixture of triphenyl phosphates and antimony trioxide being preferred, for example.
If the introduction of assemblies of the formula VIII is desired, up to 15 mol% of a carboxyphosphinic acid derivative, for example ®phospholane from Hoechst AG, is added to the polycondensation mixture.
As a rule, the polycondensation in the melt takes less than 10 hours, preferably 2-3 hours.
For the subsequent solid-phase polycondensation, the low molecular weight ester produced in the first stage is finely pulverized or pelletized and the temperature in the range from 220 to 270 ° C. is such that the polyester powder or the polyester pellets never agglomerate or sinter together or even melt. After the solid-phase polycondensation, which is carried out to the desired value of the specific viscosity, the high-molecular copolyester is melt-spun in a manner known per se to give the monofilaments according to the invention.

The copolyester is dried immediately before spinning, preferably by heating in a dry atmosphere or in a vacuum.

The core / sheath monofilaments according to the invention are used with particular advantage for or in the manufacture of textile fabrics with high mechanical and chemical resistance.

Such a technical use of the core / sheath monofilaments according to the invention is the production of paper machine screens.
One object of the present invention is therefore the use of the core / sheath monofilaments according to the invention for or in the manufacture of paper machine screens and paper machine screens, which predominantly, ie to at least 65 wt .-%, consist of the monofilaments described above, namely both paper machine wire (forming wire) and paper machine dryer fabrics.
A forming wire according to the invention in the paper machine generally has a one- to three-layer structure and has a basis weight of 100 to 800, preferably 200 to 600 g / m ² . As a rule, core / sheath monofilaments according to the invention with a diameter of 0.08 to 0.45 mm, preferably 0.13 to 0.30 mm, are used.
Core / sheath monofilaments according to the invention with a diameter of 0.20 to 1.00 mm, preferably of 0.40 to 0.8 mm, are generally used for the production of the paper machine dryer fabrics.
The monofilaments are woven on conventional wide weaving machines with the machine parameters that are also common for weaving polyethylene terephthalate to form the paper machine screens.
For example, good screenings are obtained by weaving monofilaments with a diameter of 0.17 mm in the warp with 0.2 mm oversize and 0.22 mm undershoots. The fabric has very good dimensional stability and excellent abrasion resistance.
The fabric obtained is generally post-treated on a suitably dimensioned heat setting device in order to set the specific sieving properties desired in the individual case.

The paper machine fabric produced in this way from monofilaments according to the invention has better dimensional stability in the warp and weft directions compared to a material produced from conventional polyethylene terephthalate monofilaments and thereby causes a smoother running in the paper machine, which benefits the quality of the paper produced.

A special embodiment of the paper machine screens are the so-called spiral screens. These screens consist of a variety of Monofilament spirals (coils) arranged axially parallel to one another, whose spiral spacing (pitch of the spiral) corresponds to at least twice the thickness of the monofilament, the spacing of the spirals lying next to one another being dimensioned such that the spirals interlock. A plug wire ("wire" in this context means a polyester monofilament) is inserted into the cavity formed by the helix of the two interlocking spirals, whereby the adjacent spirals are connected to one another. A so-called cored wire can also be inserted into the cavity remaining in the center of each spiral.

Because of their advantageous combination of good mechanical properties, in particular the very good abrasion resistance and high chemical stability, the core / sheath monofilaments according to the invention can also be used for or in the production of such spiral screens.
Another object of the present invention is therefore the use of the core / sheath monofilaments according to the invention for or in the manufacture of spiral sieves and spiral sieves which consist predominantly, ie at least 65% by weight, of the monofilaments described above.
As a rule, core / sheath monofilaments with a diameter of 0.4 to 1.0 mm, preferably 0.5 to 0.8 mm, are used to produce the spirals. The plug wires of these screens are expediently produced from core / sheath monofilaments according to the invention with a diameter of 0.5 to 1.5 mm, preferably 0.6 to 1.2 mm.

Another object of the present invention is the use of the core / jacket monofilaments according to the invention described above for or in the production of screen printing fabrics and the screen printing fabrics thus obtained containing a proportion of the core / jacket monofilaments according to the invention which decisively determines their properties.

Such a screen printing fabric usually shows - depending on the Diameter of the woven monofilaments - a weight per unit area of 10 to 200, preferably 20 to 100 g / m ² . As a rule, core / sheath monofilaments according to the invention with a diameter of 10 to 100 μm (corresponding to approximately 1 to 110 dtex), preferably 10 to 80 μm (corresponding to approximately 1 to 70 dtex), in particular with a diameter from 20 to 55 µm (corresponding to approx. 5 to 35 dtex).
Particularly preferred for the production of the screen printing fabrics are core / sheath monofilaments according to the invention whose sheath and optionally also their core 0.1 to 2.0% by weight of a dye and 0.1 to 0.5% by weight of a UV -Absorbers and less than 0.3 wt .-% TiO ₂ contains.

The core / sheath monofilaments according to the invention are woven on the weaving machines customary today with the machine parameters common to the screen printing fabrics, even when weaving polyethylene terephthalate.

For example, a good screen printed product is obtained by weaving monofilaments with a diameter of 0.040 mm in warp and weft in plain or twill weave. Because of the high modulus of elasticity of the monofilaments according to the invention, the fabric has a clearly superior, very good dimensional stability and abrasion resistance over a conventional polyester sieve, and thus a longer service life even under high stress. In many cases, the fabric according to the invention can be used to replace screen-printed fabrics which are still made from metal wire today.

Mechanically and chemically outstandingly stable filter materials can also advantageously be produced from core / sheath monofilaments according to the invention. Another object of the present invention is therefore the use of the core / sheath monofilaments according to the invention for or in the manufacture of filter materials and the filter materials thus obtained with a proportion of the core / sheath monofilaments according to the invention which significantly influences their properties.

Furthermore, the core / sheath monofilaments according to the invention can also advantageously be used to produce mechanically and chemically outstandingly stable, highly resilient and dimensionally stable conveyor belts or reinforcing inserts for conveyor belts. Another object of the present invention is therefore the use of the core / jacket monofilaments according to the invention for or in the production of conveyor belts and the conveyor belts thus obtained with a proportion of the core / jacket monofilaments according to the invention which significantly influences their properties.

example 1

420 g of dimethyl terephthalate, 47 g of dimethyl isophthalate, 367 g of ethylene glycol and 0.7 g of manganese acetate tetrahydrate are introduced into a 1 liter three-necked flask equipped with a nitrogen inlet and outlet, a thermometer, a descending condenser and a mechanical stirrer. The mixture was heated to 220 ° C. for 2.5 hours, during which methanol distilled off. Then 0.675 g triphenyl phosphate and 0.226 g antimony trioxide were added as a polycondensation catalyst. The mixture was then heated to 270 ° C. with stirring, vacuum was applied and the temperature was raised to 290 ° C. and the batch was held at this temperature for 2.5 hours. The polyester thus obtained has an average molecular weight of medium size; it serves as an intermediate for the production of a high molecular weight polyester by solid phase condensation.
For this purpose, the polyester is pulverized so that it passes through a 20 mesh sieve.
The powder is then further polycondensed under reduced pressure at 220 ° C. in the solid phase for 24 hours until it reaches an average molecular weight which has a specific viscosity (V _S ) of 1.37, measured in a 1% strength by weight solution in Dichloroacetic acid at 25 ° C. The polyester thus obtained has a carboxyl end group concentration of 13 meq / kg.

An even more flame-retardant polyester can be obtained in an analogous manner if 5% by weight of 2-carboxyethyl-methylphosphinic anhydride is added to the mixture after the elimination of methanol (®Phospholan from Hoechst AG) is added and the rest of the procedure is as described above.

Example 2

• A) 700 g eines nach dem Vorbild des Beispiels 1 hergestellten isophthalsäuremodifizierten Polyethylenterephthalats (V_S = 1,37) wurden granuliert und über Nacht im Vakuum getrocknet und mit 300 g eines ebenfalls im Vakuum getrockneten handelsüblichen elastomeren Polyurethans (®Desmopan VPKA 8392 der Firma Bayer AG) gründlich gemischt.
• B) 300 g eines gemäß Beispiel 1 hergestellten isophthalsäuremodifizierten Polyethylenterephthalats (V_S = 1,37) wurden über Nacht im Vakuum getrocknet.

Für die folgende Herstellung von Kern/Mantel-Monofilamenten wurde eine Spinneinrichtung eingesetzt, wie sie in der EP-A-0 434 448 beschrieben ist. Bei dieser Einrichtung weist jede Spinnöffnung einen zentral über der Austrittsöffnung angeordneten Zulauf für die Kernschmelze und einen kreisförmig um die Spinnbohrung herumführenden Zulaufschlitz für die Mantelschmelze auf. Auf diese Weise wird der zentrale Strom des Kernmaterials mit der allseitig herangeführten Schmelze der Mantelmischung umgeben.

• A) 700 g of an isophthalic acid-modified polyethylene terephthalate (V _S = 1.37) prepared according to the example of Example 1 were granulated and dried in a vacuum overnight and with 300 g of a commercially available elastomeric polyurethane (®Desmopan VPKA 8392 from Bayer, also dried in a vacuum) AG) mixed thoroughly.
• B) 300 g of an isophthalic acid-modified polyethylene terephthalate (V _S = 1.37) prepared according to Example 1 were dried in a vacuum overnight.

A spinning device as described in EP-A-0 434 448 was used for the following production of core / sheath monofilaments. In this device, each spinning opening has an inlet for the core melt arranged centrally above the outlet opening and an inlet slot for the shell melt which runs in a circle around the spinning bore. In this way, the central stream of the core material is surrounded by the melt of the jacket mixture which is brought in from all sides.

The polyester mixture prepared according to section A of this example is melted in an extruder at 240 ° C., and the melt is pressed into a spin pack by means of a metering pump. After filtration in the spin pack, the melt of the mixture is fed to the peripheral jacket feeds of the aforementioned spinnerets for the production of core / jacket monofilaments. In a separate strand consisting of extruder, metering pump and spin pack, the polyester dried according to Section B of this example is melted, filtered and fed to the central core feeds of the spinnerets.
The melt streams were in a weight ratio of 25 wt .-% jacket mixture and 75 wt .-% core polyester at a melt temperature of 240 ° C and a total throughput of 20 g / min per spinning orifice through spinning orifices with a diameter of 0.7 mm , corresponding to a Spinning delay of 2.0, extruded and quenched in a water bath. The take-off speed was 12.5 m / min.
The core / sheath monofilaments obtained are then continuously drawn in two stages at 190 ° C. in the first stage and 175 ° C. in the second stage, the drawing ratio being 1: 6.0 in the first stage and 1: 1.13 in the second stage and fixed in a 4 m long channel at 215 ° C.

Example 3

A polyester of the same composition was spun in the manner described in Example 2, but with 0.29% by weight of N, N'-di-p-tolylcarbodiimide and 0, in each case in the mixing area of the extruders, based on the respective throughput. 2% by weight of 1,5-dimethylbenzene-2,4-polycarbodiimide were metered in.

The properties of the core / sheath monofilaments obtained in this way correspond to those of those produced in Example 2, but the resistance to hydrolysis is significantly increased.

Claims (45)

Monofilaments with a core / sheath structure with a core made of a thermoplastic polyester or copolyester and a sheath containing a thermoplastic polyester, characterized in that the polyester or copolyester of the core has a melting point of 165 to 290 ° C, preferably 220 to 240 ° C , and has at least 70 mol%, based on the totality of all polyester assemblies, from assemblies derived from aromatic dicarboxylic acids and from aliphatic diols, and at most 30 mol%, based on the totality of all polyester assemblies, from carboxylic acid assemblies , which are different from the aromatic dicarboxylic acid units which form the majority of the dicarboxylic acid units, or from araliphatic dicarboxylic acids with one or more, preferably one or two condensed or uncondensed aromatic nuclei, or from cyclic or acyclic aliphatic dicarboxylic acids with a total of 4 to 12 carbon atoms , preferably 6 to 10 carbon atoms
and diol assemblies which are derived from aliphatic diols and are different from the diol assemblies which form the majority of the diol assemblies, or which are branched and / or longer-chain diols having 3 to 10, preferably 3 to 6 , Carbon atoms, or from cyclic diols, or from ether-containing diols, or, if present in small amounts, from polyglycol with a molecular weight of approx. 500 - 2000,
and the jacket consists of a polyester mixture of a thermoplastic polyester, the melting point of which is between 165 and 240 ° C., preferably 220 and 240 ° C., and a thermoplastic, elastomeric polyurethane and, if appropriate, customary non-polymeric additives. Monofilaments with a core / sheath structure according to claim 1, characterized in that the proportion of the sheath in the total cross-sectional area of the monofilament is 5 to 95%, preferably 10 to 60, the proportion of the core 5 to 95%, preferably 40 to 90. Monofilaments with a core / sheath structure according to at least one of claims 1 and 2, characterized in that the polyester of the core, based on the totality of all polyester assemblies 35 to 50 mol% of assemblies of the formula -CO-A ¹ -CO- (I) 0 to 15 mol% of assemblies of the formula -CO-A ² -CO- (II) 35 to 50 mol% of assemblies of the formula -OD ¹ -O- (III) 0 to 15 mol% of assemblies of the formula -OD ² -O- (IV)
and 0 to 25 mol% of assemblies of the formula -OA ³ -CO- (V)
is built up in what A ¹ aromatic radicals having 5 to 12, preferably 6 to 10 carbon atoms A ² different from A ¹ aromatic radicals or araliphatic radicals having 5 to 16, preferably 6 to 12 C atoms or cyclic or acyclic aliphatic radicals having 2 to 10 carbon atoms, preferably 4 to 8 carbon atoms, A ³ aromatic radicals with 5 to 12, preferably 6 to 10 carbon atoms D ¹ alkylene or polymethylene groups with 2 to 4 carbon atoms or cycloalkane or dimethylene-cycloalkane groups with 6 to 10 C atoms, D ² D ¹ different from alkylene or polymethylene groups with 3 to 4 carbon atoms or cycloalkane or dimethylene cycloalkane groups with 6 to 10 carbon atoms or straight-chain or branched alkanediyl groups with 4 to 16, preferably 4 to 8, carbon atoms or radicals of the Formula - (C ₂ H ₄ -O) _m -C ₂ H ₄ -, in which m is an integer from 1 to 40, where m = 1 or 2 are preferred for proportions up to 20 mol% and groups with m = 10 to 40 preferably only are present in proportions of less than 5 mol%. Monofilaments with a core / sheath structure according to at least one of claims 1 to 3, characterized in that in the assemblies of the polyester of the core A ^{1 is} 1,4-phenylene and D ^{1 is} ethylene and that in this polyester the assemblies I and III Make up at least 85 mol%, in particular at least 90 mol%, of all assemblies. Monofilaments with a core / sheath structure according to at least one of claims 1 to 4, characterized in that in the assemblies of the polyester of the core A ^{1 is} 2,6-naphthylene and D ^{1 is} ethylene and that in this polyester the assemblies I and III Make up at least 85 mol%, in particular at least 90 mol%, of all assemblies. Monofilaments with a core / sheath structure according to at least one of claims 1 to 5, characterized in that in the structural groups of the polyester of the core A ^{1 is} 2,6-naphthylene and biphenyl-1,4-diyl and D ^{1 is} ethylene and that preferably In this polyester, the assemblies I and III make up at least 85 mol%, in particular at least 90 mol%, of all assemblies. Monofilaments of core / sheath construction according to at least one of claims 1 to 6, characterized in that the for Group A ¹ 2,6-naphthylene and biphenyl-1,4-diyl in the mole ratio of maximum 3: 1, preferably in a molar ratio are between 6: 4 and 4: 6. Monofilaments with a core / sheath structure according to at least one of Claims 1 to 7, characterized in that A ¹ 1,4-phenylene and D ¹ 1,4-bismethylene-cyclohexane in the component groups of the polyester of the core means and that preferably in this polyester the assemblies I and III make up at least 85 mol%, in particular at least 90 mol%, of all assemblies. Monofilaments with a core / sheath structure according to at least one of Claims 1 to 8, characterized in that the polyester of the core has a specific viscosity of 0.55 to 1.6, preferably 0.58 to 1.5, measured in a first wt .-% solution of the polyester in dichloroacetic acid at 25 ° C, has. Monofilaments with a core / sheath structure according to at least one of Claims 1 to 9, characterized in that the polymer material of the polyester mixture of the sheath is 1 to 99% by weight, preferably 30 to 90% by weight, in particular 50 to 80 % By weight of the thermoplastic polyester and
1 to 99% by weight, preferably 10 to 70% by weight, in particular
consists of 20 to 50 wt .-% of the thermoplastic polyurethane. Monofilaments with a core / sheath structure according to at least one of Claims 1 to 10, characterized in that the polyester of the polyester mixture of the sheath comprises at least 70 mol%, based on the totality of all polyester assemblies, from assemblies which differ from aromatic dicarboxylic acids and derive from aliphatic diols, and up to a maximum of 30 mol%, based on the totality of all polyester assemblies, from dicarboxylic acid assemblies which are different from the aromatic dicarboxylic acid assemblies which form the majority of the dicarboxylic acid assemblies, or from araliphatic dicarboxylic acids with one or more, preferably one or two condensed or uncondensed aromatic nuclei, or derived from cyclic or acyclic aliphatic dicarboxylic acids with a total of 4 to 12 carbon atoms, preferably 6 to 10 carbon atoms,
and diol assemblies which are derived from aliphatic diols and are different from the diol assemblies which form the majority of the diol assemblies, or which are branched and / or longer-chain diols having 3 to 10, preferably 3 to 6 , Carbon atoms, or from cyclic diols, or from ether-containing diols, or, if present in small amounts, from polyglycol with a molecular weight of about 500-2000. Monofilaments with a core / sheath structure according to at least one of claims 1 to 11, characterized in that the polyester of the polyester mixture of the sheath, based on the totality of all polyester assemblies 35 to 50 mol% of assemblies of the formula -CO-A ¹ -CO- (I) 0 to 15 mol% of assemblies of the formula -CO-A ² -CO- (II) 35 to 50 mol% of assemblies of the formula -OD ¹ -O- (III) 0 to 15 mol% of assemblies of the formula -OD ² -O- (IV)
and 0 to 25 mol% of assemblies of the formula -OA ³ -CO- (V)
is built up in what A ¹ aromatic radicals having 5 to 12, preferably 6 to 10 carbon atoms A ² different from A ¹ aromatic radicals or araliphatic radicals having 5 to 16, preferably 6 to 12 C atoms or cyclic or acyclic aliphatic radicals having 2 to 10 carbon atoms, preferably 4 to 8 carbon atoms, A ³ aromatic radicals having 5 to 12, preferably 6 to 10, carbon atoms, D ¹ alkylene or polymethylene groups with 2 to 4 carbon atoms or cycloalkane or dimethylene-cycloalkane groups with 6 to 10 C atoms, D ² D ¹ different from alkylene or polymethylene groups with 3 to 4 carbon atoms or cycloalkane or dimethylene cycloalkane groups with 6 to 10 carbon atoms or straight-chain or branched alkanediyl groups with 4 to 16, preferably 4 to 8, carbon atoms or radicals of the formula - (C ₂ H ₄ -O) _m -C ₂ H ₄ -, in which m is an integer from 1 to 40, where m = 1 or 2 are preferred for proportions up to 20 mol% and Groups with m = 10 to 40 are preferably present only in proportions of less than 5 mol%. Monofilaments with a core / sheath structure according to at least one of claims 1 to 12, characterized in that in the assemblies of the polyester of the polyester mixture of the sheath A ^{1 is} 1,4-phenylene and 1,3-phenylene and D ^{1 is} ethylene, the molar ratio of 1,4- and 1,3-phenylene is chosen so that the polyester has a melting point in the range from 220 to 240 ° C., and that in this polyester the assemblies I and III are preferably at least 85 mol%, in particular at least Make up 90 mol% of all assemblies. Monofilaments with a core / sheath structure according to at least one of claims 1 to 13, characterized in that the polyester contained in the polyester mixture of the sheath has a specific viscosity from 0.55 to 1.6, preferably from 0.58 to 1.5, measured in a 1 wt .-% solution of the polyester in dichloroacetic acid at 25 ° C. Monofilaments with a core / sheath structure according to at least one of claims 1 to 14, characterized in that both the polyester of the core and the polyester contained in the polyester mixture of the sheath have a melting point between 220 and 240 ° C. Monofilaments with a core / sheath structure according to at least one of claims 1 to 15, characterized in that the polyester of the core and the polyester of the polyester mixture of the sheath have the same chemical composition. Monofilaments with a core / sheath structure according to at least one of the Claims 1 to 16, characterized in that the polyester of the core and the polyester of the polyester mixture of the sheath not more than 60 meq / kg, preferably less than 30 meq / kg, blocked carboxyl end groups and less than 5 meq / kg, preferably less than 2 mVal / kg, in particular less than 1.5 mVal / kg, has free carboxyl end groups. Monofilaments with a core / sheath structure according to at least one of Claims 1 to 17, characterized in that the polyester of the core and the polyester of the polyester mixture of the sheath have carboxyl end groups blocked by reaction with mono-, bis- and / or polycarbodiimides. Monofilaments with a core / sheath structure according to at least one of claims 1 to 18, characterized in that the polyester subassemblies of the formula VIII,

wherein R is alkylene or polymethylene with 2 to 6 carbon atoms or phenyl, preferably ethylene, and R ^{1 is} alkyl with 1 to 6 carbon atoms, aryl or aralkyl, preferably methyl, contains condensed. Monofilaments with a core / sheath structure according to at least one of Claims 1 to 19, characterized in that the elastomeric polyurethane of the polyester mixture of the sheath has a shear modulus which has a value of 8 to 80 MPa, preferably of, in the temperature range from 20 to 60 ° C 20 to 50 MPa, has a mechanical loss factor tan (δ) which has a value of 0.8x10 ^-2 to in the temperature range from 20 to 60 ° C 1.2x10 ^-1 ,
a Shore hardness A, measured according to DIN 53505, from 82 to 100, a Shore hardness D, measured according to DIN 53505, from 30 to 60 a tensile strength, measured according to DIN 53504, from 32 to 42 MPa an elongation at break, measured according to DIN 53504, from 420 to 520% and an impact resistance, measured according to DIN 53515, from 32 to 45%. Monofilaments with a core / sheath structure according to at least one of claims 1 to 20, characterized in that the elastomeric polyurethane of the polyester mixture of the sheath corresponds to the idealized formula IX,

wherein R ^{1 is} a double-bonded, aromatic or araliphatic radical having 6 to 18 carbon atoms with an optionally substituted aromatic ring or with two condensed or uncondensed, optionally substituted aromatic rings, R ^{2 is} a polyether assembly of the formula X,

wherein X ^{3 represents} hydrogen or methyl, and m is a number from 10 to 100, preferably from 10 to 30 or R ^{2 is} the rest of the polytetrahydrofuran or, preferably an assembly of formula XI

in which R ³ straight-chain or optionally branched alkane-diyl or oxy-alkane-diyl having 2 to 8, preferably 2 to 6, carbon atoms, such as, for example, ethylene, propane-1,3-diyl, butane-1,4-diyl, Hexane-1,6-diyl, 2-ethylhexane-1,6-diyl, 2,2-dimethylpropane-1,3-diyl or the divalent oxaalkane-diyl radicals derived from diethylene glycol or triethylene glycol, R ⁴ alkane-diyl with 2 to 6, preferably 2 to 4 carbon atoms, cycloalkane-diyl such as cyclohexane-1,4 or 1,3-diyl or a divalent aromatic radical with 6 to 12 carbon atoms, preferably 6 to 10 Carbon atoms, in particular 1,3- or 1,4-phenylene, p is a number which is chosen such that the polyester assembly of the formula (XI) has a molecular weight of 1000 to 2000 (p = 5 to 12, preferably 8 to 11) and q means either 0 or 1. Monofilaments with a core / sheath structure according to at least one of Claims 1 to 21, characterized in that they have a titer of 1 to 24400 dtex (in the case of a round cross section corresponding to filament diameters of 10 to 1500 µm) and a round, elliptical or n-angular cross-sectional shape have, with an elliptical shape the ratio of large axis to small axis is up to 10: 1 and n n 4, preferably 4 to 8. Monofilaments with a core / sheath structure according to at least one of Claims 1 to 22, characterized in that they have an initial modulus at 25 ° C of over 10, preferably over 12 N / tex and / or a fineness-related maximum tensile force of over 18 cN / tex , preferably from 20 to 45 cN / tex and / or a dry heat shrinkage, measured at 180 ° C. of over 0.5%, preferably from 1 to 25%. Monofilaments with a core / sheath structure according to at least one of Claims 1 to 23, characterized in that the polyester of the core and / or the polyester mixture of the sheath comprises up to 10% by weight of non-polymeric substances, such as modification additives, fillers, matting agents, pigments , Dyes, stabilizers, such as UV absorbers, antioxidants, hydrolysis, light and temperature stabilizers and / or processing aids. Monofilaments with a core / sheath structure according to at least one of claims 1 to 24, characterized in that the polyester of the core and / or the polyester mixture of the sheath are colored differently. Monofilaments with a core / sheath structure according to at least one of claims 1 to 25, characterized in that the polyester of the core and / or the polyester mixture of the sheath contain different dyes. Monofilaments with a core / sheath structure according to at least one of claims 1 to 26, characterized in that either the polyester of the core or the polyester mixture of the sheath contain up to 5% by weight of a dye and the other filament component is natural in color. A process for producing the core / sheath monofilaments of claim 1, characterized in that a spinnable thermoplastic polyester for the core, as defined in claim 1, and a polyester mixture for the sheath, as defined in claim 1, in each melted separately in an extruder, and spun at melt temperatures of 185 to 320 ° C with a spinning delay of 1: 1.5 to 1: 5, preferably 1: 2 to 1: 3, cooled in a spinning bath and wound or drawn off, the the spun thread thus produced is then subjected to post-drawing in a total drawing ratio of 1: 4 to 1: 8, and then heat-set at temperatures of 160 to 250 ° C., with a constant length or with approval of 2 to 30% shrinkage. A method according to claim 28, characterized in that the polyesters of the core and the polyester mixture of the sheath, before spinning, 1.0 to 1.2 times the amount, which is equivalent to the amount of free carboxyl end groups contained therein, of mono-, Bis- and / or polycarbodiimides are added. A method according to at least one of claims 28 and 29, characterized in that the polyesters of the core and the polyester mixture of the sheath prior to spinning an amount of at most 0.6 wt .-% of a mono- and / or biscarbodiimide and at least 0.05 wt .-% % of a polycarbodiimide is added. Process according to at least one of claims 28 to 30, characterized in that polyesters are used which contain components of the formula VIII. Process according to at least one of Claims 28 to 31, characterized in that spinning is carried out at a melting temperature in the range from 210 to 250 ° C. Process according to at least one of claims 28 to 32, characterized in that the monofilaments are drawn off at a spinning take-off speed of 5 to 30 m per minute will. Use of the monofilaments of claim 1 for or in the manufacture of textile fabrics with high mechanical and chemical resistance. Use of the monofilaments of claim 1 for or in the manufacture of paper machine screens. Use of the monofilaments of claim 1 for or in the manufacture of spiral screens. Use of the monofilaments of claim 1 for or in the manufacture of screen printing fabrics. Use of the monofilaments of claim 1 for the manufacture of technical filter fabrics. Use of the monofilaments of claim 1 for or in the production of conveyor belts. Textile fabric with high mechanical and chemical resistance, characterized in that it contains or consists of core / sheath monofilaments of claim 1. Paper machine screen, characterized in that it contains or consists of core / sheath monofilaments of claim 1. Spiral sieve, characterized in that it contains or consists of core / sheath monofilaments of claim 1. Screen printing fabric, characterized in that it contains core / sheath monofilaments of claim 1 contains or consists thereof. Technical filter fabric, characterized in that it contains or consists of core / sheath monofilaments of claim 1. Conveyor belt, characterized in that it contains or consists of core / sheath monofilaments of claim 1.