EP0735166B1 - 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 manufactured from it technical products, in particular paper machine screens, fabrics for the Screen printing and for technical filter materials. The invention Core / sheath monofilaments have a polyester core and a sheath a mixture of a thermoplastic polyester and a thermoplastic elastomeric polyurethane.

Monofilaments for technical applications are in most cases Use subject to high mechanical loads. Add to that in many cases thermal and chemical and chemical stress other environmental influences for which the material is adequate Must oppose resistance. With all these loads, the material good dimensional stability and constant force-stretch properties over long periods of use.

An example of technical applications where a combination of high mechanical, thermal and chemical stress is present Use of monofilaments in paper machine screens, especially in so-called fourdrinier. This use also requires a monofilament material high initial modulus and high tear strength, a good knot and Loop resistance and high abrasion resistance to the high To withstand stress and a sufficient service life of the sieve guarantee. In the dryer section of the paper machine next to these Parameters also require a high hydrolysis resistance of the monofilament.

Similar high demands are placed on the monofilament material at Use in screen printing fabrics that are under constant stress from the under squeegee working under high pressure, watery due to hydrolytic attack Dough dyes and under the influence of highly actinic light sources for a long time Should have downtimes. In doing so, the screen printing fabric will be special high demands are placed on the dimensional stability, so the production precise multi-color printing is possible.

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 a 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 sheathed 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 use very polyester fibers different mechanical and textile properties to manufacture. In particular, it is possible through variations in spinning and Stretching and relaxation conditions made of polyethylene terephthalate Manufacture monofilaments covering a wide range of technical Cover relevant monofilament properties.

Efforts to obtain a monofilament material that is also suitable for Paper machine screens require high dimensional stability, abrasion resistance and hydrolysis resistance with high resistance to actinic light required for the production of screen printing fabrics to unite, however, have 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, since too rapid crystallization leads to early embrittlement of the monofilaments during the manufacturing process, with the result that they tear off before adequate 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 use monofilaments manufacture a combination of further improved mechanical application-relevant properties, high stability against actinic radiation and have high chemical stability, in particular hydrolysis stability, and which are therefore accessible to an expanded range of technical applications. These monofilaments consist essentially of polyesters - the The term "polyester" in the sense of the present invention also includes copolyester comprises - 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 which are 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 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, and the proportion of the jacket the total cross-sectional area of the monofilament is 5-95% and that of the core is 5-95% and the polyester mixture of the jacket consists of 1-99% by weight of the thermoplastic polyester and 1-99% by weight of the thermoplastic polyurethane.

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

35 bis 50 Mol-% Baugruppen der Formel -CO-A¹-CO-

0 bis 15 Mol-% Baugruppen der Formel -CO-A²-CO-

35 bis 50 Mol-% Baugruppen der Formel -O-D¹-O-

0 bis 15 Mol-% Baugruppen der Formel -O-D²-O-

und

0 bis 25 Mol.-% Baugruppen der Formel -O-A³-CO-

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-

0 to 15 mol% of assemblies of the formula -CO-A ² -CO-

35 to 50 mol% of assemblies of the formula -OD ¹ -O-

0 to 15 mol% of assemblies of the formula -OD ² -O-

and

0 to 25 mol% of assemblies of the formula -OA ³ -CO-

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, the symbols A ¹ in the assemblies I and III of the core polyester mean 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 from 0.55 to 1.6, preferably from 0.58 to 1.5, measured in a 1% by weight Solution of the polyester in dichloroacetic acid at 25 ° C.

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

The polymer material of the polyester mixture of the jacket preferably consists of 30 to 90% by weight, in particular 50 to 80% by weight, of the thermoplastic polyester and preferably 10 to 70% by weight, in particular 20 to 50% by weight made of 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 one Glass point in the range from 60 to 120 ° C, in particular from 70 to 85 ° C, one Crystallization point in the range from 135 to 155 ° C, in particular from 140 to 150 ° C, and a melting point in the 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 which 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 quantities, from polyglycol with a molecular weight of about 500-2000.

35 bis 50 Mol-% Baugruppen der Formel CO-A¹-CO-

0 bis 15 Mol-% Baugruppen der Formel -CO-A²-CO-

35 bis 50 Mol-% Baugruppen der Formel -O-D¹-O-

0 bis 15 Mol-% Baugruppen der Formel -O-D²-O-

und

0 bis 25 Mol.-% Baugruppen der Formel -O-A³-CO-

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-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 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-

0 to 15 mol% of assemblies of the formula -CO-A ² -CO-

35 to 50 mol% of assemblies of the formula -OD ¹ -O-

0 to 15 mol% of assemblies of the formula -OD ² -O-

and

0 to 25 mol% of assemblies of the formula -OA ³ -CO-

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 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 in the polyester mixture of Sheath contained polyester a specific viscosity of 0.55 to 1.6, preferably from 0.58 to 1.5, measured in a 1% by weight solution of the Has polyester in dichloroacetic acid at 25 ° C, and / or if both Polyester of the core as well as the polyester that is in the polyester blend of Sheath is included, 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 blend 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 from the above described polyesters, in particular made of polyethylene terephthalate, are not easily inflamed.

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 additions of halogen compounds, in particular bromine compounds, or, which is particularly advantageous, they contain phosphorus compounds which are condensed into the polyester chain. 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.

einen Schermodul auf, der im Temperaturbereich von 20 bis 60°C einen Wert von 8 bis 80 MPa, vorzugsweise von 20 bis 50 MPa, hat,

einen mechanischen Verlustfaktor tan(δ), der im Temperaturbereich von 20 bis 60°C einen Wert von 0,8*10^-2 bis 1,2*10^-1 hat,

eine Shore-Härte A, gemessen nach DIN 53505, von 82 bis 100,

eine Shore-Härte D, gemessen nach DIN 53505, von 30 bis 60

eine Zugfestigkeit, gemessen nach DIN 53504, von 32 bis 42 MPa

eine Bruchdehnung, gemessen nach DIN 53504, von 420 bis 520 %

und eine Schlagzähigkeit, gemessen nach DIN 53515 von 32 bis 45 %.

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 has a value of 0.8 * 10 ^-2 to 1.2 * 10 ^-1 in the temperature range from 20 to 60 ° C,

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

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 so 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 from 1 to 24400 dtex (with a round cross-section accordingly Filament diameters from 10 to 1500 µm) and a round, elliptical or polygonal Cross-sectional shape, with elliptical shape the ratio of large Axis too small axis is up to 10: 1 and n ≥ 4, preferably 4 to 8, is.

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 strength is usually in the range of over 7%, preferably from 8 to 18%.

The monofilaments of the invention can be other than that described above Copolyester still does not contain small amounts of additives and additives polymeric in nature, such as. B. catalyst residues, Modifying additives, fillers, matting agents, pigments, dyes, Stabilizers, such as UV absorbers, antioxidants, hydrolysis, light and Temperature stabilizers and / or processing aids, plasticizers or Lubricant. Usually these additives are at a maximum concentration 10% by weight, preferably 0.01-5% by weight, in particular 0.1-2% by weight available. The catalyst residues can be, for example Act antimony trioxide or tetraalkoxy titanates. As a processing aid or lubricants can be siloxanes, especially polymeric dialkyl or Diarylsiloxanes, salts and waxes and longer-chain organic carboxylic acids, these are those with more than 6 carbon atoms, aliphatic, aromatic and / or perfluorinated esters and ethers are used in amounts of up to 1% by weight become. The monofilaments can also be inorganic or organic Contain 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 moreover, if necessary, also viscosity modifiers and substances to modify the Crystallite melting point or the glass transition temperature or those which the Crystallization kinetics, or influence the degree of crystallization, used become. For example, viscosity modifiers are used polyvalent 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 finished polymers mixed in a small amount or, preferably, as Copolymerization components in the manufacture of the polymers in the desired Quantity added.

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 method for Production of the core / sheath monofilaments according to the invention described above, the thermoplastic polyester for the core and a Polyester mixture for the jacket separated in an extruder melted, 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 out, cooled in a spinning bath and the wound filament is then wound or drawn off post-drawing in the total drawing ratio of 1: 4 to 1: 8 subjected, and then at temperatures of 160 to 250 ° C, at constant length or heat-set with approval of 2 to 30% shrinkage becomes.

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 which are 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.

The spinning can be done by a special, for the production of core / sheath filaments with central opening and one or more peripheral Spinneret provided with jacket openings. The melts for core and The jackets are then filtered in a spin pack, the thermoplastic Polyester of the core opening, the abrasion-resistant polyester mixture of the jacket opening fed to a spinneret for the production of core / sheath monofilaments. In another, very advantageous embodiment of the invention The core polyester process and the polyester blend for the jacket of the monofilament is fed to the periphery of a spin pack and spun through a simple spinning opening. This technology is have been described in detail in EP-A-0 434 448. It leads to core / sheath 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 for Achieving a specific combination of monofilament properties can routinely by determining the dependency of those under consideration Monofilament property from the composition of the polyester and 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, 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 to a higher molecular weight polyester in a molten state at a reaction temperature of approximately 240-290 ° C. in the presence of a polycondensation catalyst. This polycondensation is carried out up to an IV of about 0.5 to 0.8 dl / g. 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 modules 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 up to the desired value of the specific viscosity, the high molecular weight copolyester is melt-spun in a manner known per se to give the monofilaments according to the invention.

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

The core / sheath monofilaments according to the invention are particularly useful 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 at least 65% by weight, consist of the monofilaments described above, namely both paper machine Fourdrinier wire (forming wire) as well as paper machine dry wire.
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.

That produced in this way from monofilaments according to the invention Paper machine fabric has compared to a conventional one Polyethylene terephthalate monofilaments made a better material Dimensional stability in warp and weft direction and thereby causes a smoother running in the paper machine what the quality of the paper produced benefits.

A special embodiment of the paper machine screens are so-called spiral sieves. These screens consist of a variety of monofilament spirals (coils) arranged parallel to one another, whose spiral spacing (slope of the spiral) is at least twice the thickness of the Corresponds to monofilaments, with the spacing of the adjacent Spirals are dimensioned so that the helix interlock. In the through the The spiral of the two interdigitated spirals becomes a Plug wire ("wire" in this context means a polyester monofilament) inserted, creating the adjacent spirals with each other get connected. In those remaining at the center of each spiral A so-called cored wire can also be inserted into the cavity.

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 Core / sheath monofilaments according to the invention described above for or in the production of screen printing fabrics and the so obtained Screen printing fabric containing one of their properties is decisive determining proportion of the core / sheath monofilaments according to the invention.

Such a screen printing fabric generally has - 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 based on today usual weaving machines with the also when weaving Polyethylene terephthalate machine parameters to the Screen printed fabrics woven.

For example, good screen printed goods are obtained by weaving Monofilament with 0.040 mm diameter in warp and weft in canvas or Twill weave. The fabric has a high elastic modulus monofilaments of the invention a conventional polyester screens clearly superior, very good dimensional stability and abrasion resistance, and thus a longer service life even under high loads. In many cases can be replaced by the fabric according to the invention screen-printed fabric, which are still made of metal wire today.

Core / sheath monofilaments according to the invention can also be used with advantage mechanically and chemically superior stable filter materials become. Another object of the present invention is therefore Use of the core / sheath monofilaments according to the invention for or at the production of filter materials and the filter materials thus obtained a portion of the core / sheath monofilaments according to the invention.

Furthermore, from the core / sheath monofilaments according to the invention also with advantage mechanically and chemically outstanding stable, heavy-duty and dimensionally stable conveyor belts or reinforcing inserts for conveyor belts getting produced. Another object of the present invention is hence the use of the core / sheath monofilaments according to the invention or in the production of conveyor belts and the conveyor belts thus obtained with a proportion of the core / sheath monofilaments according to the invention.

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-resistant polyester can be obtained in an analogous manner if the approach after the elimination of methanol 5 wt .-% 2-carboxyethyl-methylphosphinic anhydride (®Phospholan from Hoechst AG) is added and the rest of the work continues 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 a along the lines of Example 1 produced isophthalsäuremodifizierten polyethylene terephthalate (V _S = 1.37) were granulated and dried in vacuo overnight with 300 g of a likewise vacuum-dried commercially available elastomeric polyurethane (®Desmopan VPKA 8392 from Bayer 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 the 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, respectively 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

In the manner described in Example 2, a polyester was the same Composition spun, but in the mixing area of the extruder in each case - based on the respective throughput - 0.29% by weight of N, N'-di-p-tolylcarbodiimide and 0.2% by weight of 1,5-dimethylbenzene-2,4-polycarbodiimide added.

The properties of the core / sheath monofilaments obtained in this way correspond those of those produced in Example 2, however, the resistance to hydrolysis is clear elevated.

Claims (45)

1. Monofilaments having a core/sheath structure with a core of a thermoplastic polyester or copolyester and a sheath containing a thermoplastics polyester,
   characterised in that the polyester or copolyester of the core has a melting point of 165 to 290°C and preferably 220 to 240°C and consists up to at least 70 mol% in relation to the totality of all polyester constituents, of constituents derived from aromatic dicarboxylic acids and aliphatic diols and up to a maximum 30 mol% in relation to the totality of all polyester constituents, of dicarboxylic acid constituents which are different from the aromatic dicarboxylic acid constituents which form the predominant part of the dicarboxylic acid constituents, or are derived from araliphatic dicarboxylic acids with one or a plurality of, preferably one or two condensed or non-condensed aromatic cores, or from cyclic or acyclic aliphatic dicarboxylic acids with altogether 4 to 12 C-atoms and preferably 6 to 12 C-atoms and from diol constituents derived from aliphatic diols and different from the diol constituents which form the predominant part of the diol constituents or which are derived from branched and/or longer-chain diols with 3 to 10 and preferably 3 to 6 C-atoms or from cyclic diols or from diols containing ether groups or, where present in minimal amount, from polyglycol with a molecular weight of approx. 500 to 2,000, and the sheath 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 possibly conventional non-polymeric additives, and the proportion of sheath to the entire cross-sectional area of the monofilament amounting to 5 to 95% and that of the core 5 to 95% and the polyester mixture of the sheath representing up to 1 to 99% by weight of the thermoplastic polyester and 1 to 99% of the thermoplastic polyurethane.
2. Monofilaments having a core/sheath structure according to claim 1, characterised in that the sheath portion of the total cross-sectional area of the monofilament amounts to 10 to 60% while the core portion amounts to 40 to 90%.
3. Monofilaments having a core/sheath structure according to at least one of claims 1 and 2, characterised in that the polyester of the core, in relation to the totality of all polyester constituents, is made up of

   35 to 50 mol% constituents to formula -CO-A¹-CO-

   0 to 15 mol% constituents to formula -CO-A²-CO-

   35 to 50 mol% constituents to formula -O-D¹-O-

   0 to 15 mol% constituents to formula -O-D²-O- and

   0 to 25 mol% constituents to formula -O-A³-CO-

   in which

   A¹ denotes aromatic radicals with 5 to 12 and preferably 6 to 10 C-atoms

   A² denotes aromatic radicals different from A¹ or araliphatic radicals with 5 to 16, preferably 6 to 12 C-atoms or cyclic or acyclic aliphatic radicals with 2 to 10 carbon atoms, preferably 4 to 8 carbon atoms

   A³ denotes aromatic radicals with 5 to 12 and preferably 6 to 10 C-atoms

   D¹ denotes alkylene or polymethylene groups with 2 to 4 carbon atoms or cycloalkane or dimethylene cycloalkane groups with 6 to 10 C-atoms

   D² denotes alkylene or polymethylene groups different from D¹ and having 3 to 4 carbon atoms or cycloalkane or dimethylene cycloalkane groups with 6 to 10 C-atoms or straight-chain or branched alkane diyl groups with 4 to 16 and preferably 4 to 8 C-atoms or radicals to formula -(C₂H₄-O)_m-C₂H₄-, in which m is a whole number from 1 to 40, whereby m = 1 or 2 for fractions up to 20 mol% and denoting groups in which m = 10 to 40 are preferably only present in fractions of less than 5 mol%.
4. Monofilaments having a core/sheath structure according to at least one of claims 1 to 3, characterised in that the constituents of the polyester of the core A¹ denotes 1,4-phenylene and D¹ denotes ethylene and in that preferably in this polyester the constituents I and III represent at least 85 mol% and in particular at least 90 mol% of all the constituents.
5. Monofilaments having a core/sheath structure according to at least one of claims 1 to 4, characterised in that in the constituents of the polyester of the core A¹ denotes 2,6-naphthalene and D¹ denotes ethylene and in that preferably in this polyester the constituents I and III represent at lest 85 mol% and in particular at least 90 mol% of all constituents.
6. Monofilaments having a core/sheath structure according to at least one of claims 1 to 5, characterised in that in the constituents of the polyester of the core A¹ denotes 2,6-naphthalene and biphenyl-1,4-diyl and D¹ denotes ethylene and in that preferably in this polyester the constituents 1 and III represent at least 85 mol% and in particular at least 90 mol% of all constituents.
7. Monofilaments having a core/sheath structure according to at least one of claims 1 to 6, characterised in that the groups 2,6-naphthalene and biphenyl-1,4-diyl standing for A' are present in the molar ratio of a maximum 3 : 1, preferably in a molar ratio of between 6 : 4 and 4 : 6.
8. Monofilaments having a core/sheath structure according to at least one of claims 1 to 7, characterised in that in the constituents of the polyester of the core A¹ denotes 1,4-phenylene and D¹ denotes 1,4-bismethylene-cyclohexane and in that preferably in this polyester the constituents I and III represent at least 85 mol% and in particular at least 90 mol% of all constituents.
9. Monofilaments having a core/sheath structure according to at least one of claims 1 to 8, characterised in that the polyester of the core has a specific viscosity of 0.55 to 1.6 and preferably 0.58 to 1.5 measured in a 1% by weight solution of the polyesters in dichloroacetic acid at 25°C.
10. Monofilaments having a core/sheath structure according to at least one of claims 1 to 9, characterised in that the polymer material of the polyester mixture of the sheath consists up to 30 to 90% by weight and in particular up to 50 to 80% by weight of the thermoplastic polyester and up to 10 to 70% by weight and in particular up to 20 to 50% by weight of the thermoplastic polyurethane.
11. Monofilaments having a core/sheath structure according to at least one of claims 1 to 10, characterised in that the polyester of the polyester mixture of the sheath is up to at least 70 mol% in relation to the totality of all polyester groups derived from constituents which are derived from aromatic dicarboxylic acids and from aliphatic diols and up to a maximum of 30 mol% in relation to the totality of all polyester constituents, from dicarboxylic acid constituents which differ from the aromatic dicarboxylic acid constituents which form the predominant part of the dicarboxylic acid constituents or are derived from araliphatic dicarboxylic acids with one or a plurality of and preferably one or two condensed or non-condensed aromatic nuclei or from cyclic or acyclic aliphatic dicarboxylic acids having altogether 4 to 12 C-atoms and preferably 6 to 10 C-atoms, and diol constituents which are derived from aliphatic diols and which are different from the diol constituents which form the predominant part of the diol constituents or which are derived from branched and/or longer chain diols with 3 to 10 and preferably 3 to 6 C-atoms or from cyclic diols or from diols which contain ether groups or, where present in a minimal amount, from polyglycol with a molecular weight of approx.500 to 2,000.
12. Monofilaments having a core/sheath structure according to at least one of claims 1 to 11, characterised in that the polyester of the polyester mixture of the sheath, in relation to the totality of all the polyester groups, is built up from

    35 to 50 mol% constituents to formula -CO-A¹-CO-

    0 to 15 mol% constituents to formula -CO-A²-CO-

    35 to 50 mol% constituents to formula -O-D¹-O-

    0 to 15 mol% constituents to formula -O-D²-O- and

    0 to 25 mol% constituents to formula -O-A³-CO-

    in which

    A¹ denotes aromatic radicals having 5 to 12 and preferably 6 to 10 C-atoms

    A² denotes aromatic radicals different from A¹ or araliphatic radicals with 5 to 16, preferably 6 to 12 C-atoms or cyclic or acyclic aliphatic radicals with 2 to 10 carbon atoms, preferably 4 to 8 carbon atoms

    A³ denotes aromatic radicals with 5 to 12 and preferably 6 to 10 C-atoms

    D¹ denotes alkylene or polymethylene groups with 2 to 4 carbon atoms or cycloalkane or dimethylene cycloalkane groups with 6 to 10 C-atoms

    D² denotes alkylene or polymethylene groups different from D¹ and having 3 to 4 carbon atoms or cycloalkane or dimethylene cycloalkane groups with 6 to 10 C-atoms or straight-chain or branched alkane diyl groups with 4 to 16 and preferably 4 to 8 C-atoms or radicals to formula -(C₂H₄-O)_m-C₂H₄-, in which m is a whole number from 1 to 40, whereby m = 1 or 2 for fractions up to 20 mol% and denoting groups in which m = 10 to 40 are preferably only present in fractions of less than 5 mol%.
13. Monofilaments having a core/sheath structure according to at least one of claims 1 to 12, characterised in that in the constituents of the polyester of the polyester mixture of the sheath A¹ denotes 1,4-phenylene and 1,3-phenylene and D¹ denotes ethylene, the molar ratio of 1,4- and 1,3-phenylene being so chosen that the polyester has a melting point in the range from 220 to 240°C and in that preferably in this polyester the constituents I and III represent at least 85 mol% and in particular at least 90 mol% of all the constituents.
14. Monofilaments having a core/sheath structure according to at least one of claims 1 to 13, characterised in that the polyester contained in the polyester mixture of the sheath has a specific viscosity of 0.55 to 1.6 and preferably 0.58 to 1.5, measured in a 1% by weight solution of the polyester in dichloroacetic acid at 25°C.
15. Monofilaments having a core/sheath structure according to at least one of claims 1 to 14, characterised in that both the polyester of the core and also the polyester contained in the polyester mixture of the sheath has a melting point between 220 and 240°C.
16. Monofilaments having a core sheath structure according to at least one of claims 1 to 15, characterised in that the polyester of the core and the polyester of the polyester mixture ofthe sheath have the same chemical composition.
17. Monofilaments having a core sheath structure according to at least one of claims 1 to ] 6, characterised in that the polyester of the core and the polyester of the polyester mixture of the sheath comprises no more than 60 mVal/kg, preferably less than 30 mVal/kg of capped carboxyl end groups and less than 5 mVal/kg and preferably less than 2 mVal/kg and in particular less than 1.5 mVal/kg free carboxyl end groups.
18. Monofilaments having a core/sheath structure according to at least one of claims 1 to 17, characterised in that the polyester of the core and the polyester of the polyester mixture of the sheath comprise carboxyl end groups capped by reaction with mono-, bis- and/or polycarbodiimides.
19. Monofilaments having a core/sheath structure according to at least one of claims 1 to 18, characterised in that the polyester contains condensed-in constituents to formula VIII

    

    in which R denotes alkylene or polymethylene with 2 to 6 C-atoms or phenyl, preferably ethylene, and R¹ denotes alkyl with 1 to 6 C-atoms, aryl or aralkyl, preferably methyl.
20. Monofilaments having a core/sheath structure according to at least one of claims 1 to 19, characterised in that the elastomeric polyurethane of the polyester mixture of the sheath has a shear modulus which in the temperature range from 20 to 60°C, has a value of 8 to 80 MPa, preferably 20 to 50 MPa, a mechanical loss factor tan(δ) which in the temperature range from 20 to 60°C has a value of 0.8 x 10^-2 to 1.2 x 10^-1, a Shore hardness A measured according to DIN 53 505 of 82 to 100, a Shore hardness D measured according to DIN 53505 of 30 to 60, a tensile strength measured to DIN 53 504 of 32 to 44 MPa, a breaking elongation value measured to DIN 53504 of 420 to 520% and an impact strength measured to DIN 53515 of 32 to 45%.
21. Monofilaments having a core/sheath structure according to at least one of claims 1 to 20, characterised in that the elastomeric polyurethane of the polyester mixture of the sheath corresponds to the idealised formula IX

    

    in which

    R¹ is a double-bond aromatic or araliphatic radical with 6 to 18 C-atoms with a possibly substituted aromatic ring or with two condensed or non-condensed possibly substituted aromatic rings,

    R² is a polyether constituent to formula X

    

    in which

    X³ stands for hydrogen or methyl and m is a number from 10 to 100 and preferably from 10 to 30 or R² is the radical of polytetrahydrofurane or preferably a constituent to formula XI

    

    in which R³ denotes straight chain or possibly branched alkyl diyl or oxyalkane diyl with 2 to 8 and preferably 2 to 6 C-atoms such as for example ethylene, propane-1,3-diyl, butane-1,4-diyl, hexane-1,6-diyl, 2-ethyl hexane-1,6-diyl, 2,2-dimethyl propane-1,3-diyl or the bivalent oxa-alkane diyl radicals derived from diethylene glycol or triethylene glycol, R⁴ denotes alkane diyl with 2 to 6 and preferably 2 to 4 C-atoms, cycloalkane diyl such as cyclohexane-1,4 or 1,3-diyl and a double bond aromatic radical with 6 to 12 C-atoms and preferably 6 to 10 C-atoms, particularly 1,3- or 1,4-phenylene,

    p is a number so chosen that the polyester constituent of formula Xl has a molecular weight of 1,000 to 2,000 (p = 5 to 12 and preferably 8 to 11, and

    q means either 0 or 1.
22. Monofilaments having a core/sheath structure according to at least one of claims 1 to 21, characterised in that it has a titer of 1 to 24400 dtex (for circular cross-section corresponding to filament diameters of 10 to 1500 µm) and a circular elliptical or n-agonal cross-sectional form, whereby with elliptical form the ratio of major axis to minor axis amounts to up to 10:1 and n is ≥4 and preferably 4 to 8.
23. Monofilaments having a core/sheath structure according to at least one of claims 1 to 22, characterised in that it has a starting modulus at 25°C of over 10, preferably of over 12 N/tex and/or a fineness-related maximum tensile strength of over 18 cN/tex, preferably 20 to 40 cN/tex and/or a dry heat shrinkage value, measured at 180°C, of over 0.5% and preferably 1 to 25%.
24. Monofilaments having a core/sheath structure according to at least one of claims 1 to 23, characterised in that the polyester of the core and/or the polyester mixture of the sheath contains up to 10% by weight of non-polymeric substances such as modifying additives, fillers, matting agents, pigments, dyes, stabilisers such as UV absorbers, anti-oxidants, hydrolysis, light and temperature stabilisers and/or processing aids.
25. Monofilaments having a core/sheath structure according to at least one of claims 1 to 24, characterised in that the polyester of the core and/or the polyester mixture of the sheath are differently coloured.
26. Monofilaments having a core/sheath structure according to at least one of claims 1 to 25, characterised in that the polyester ofthe core and/or the polyester mixture of the sheath contain different dyes.
27. Monofilaments having a core/sheath structure according to at least one of claims 1 to 26, characterised in that either the polyester of the core or the polyester mixture of the sheath contains up to 5% by weight of a dyestuff while the other filament constituent is naturally coloured.
28. A method of producing the core/sheath monofilaments of claim 1, characterised 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, are separately melted in an extruder and are spun out at fusion temperatures of 185 to 320°C with a spinning delay of 1 : 1.5 to 1 : 5 and preferably 1 : 2 to 1 : 3, cooled in a spinning bath, wound up or pulled off, the spun thread so produced then being subjected to a secondary stretching operation with a total stretching ratio of 1: 4 to 1 : 8 and then heat-set at temperatures of 160 to 250°C at a constant length and with an allowance of 2 to 30% shrinkage.
29. A method according to claim 28, characterised in that prior to the spinning stage, 1.0 to 1.2 times the amount of mono-, bis and/or polycarbodiimides equivalent to the amount of free carboxyl end groups contained in the polyesters of the core and polyester mixture of the sheath are added to these latter.
30. A method according to at least one of claims 28 and 29, characterised in that prior to spinning, an amount of not more than 0.6% by weight of a mono- and/or bicarbodiimide and at least 0.05% by weight of a polycarbodiimide are added to the polyesters of the core and to the polyester mixture of the sheath.
31. A method according to at least one of claims 28 to 30, characterised in that polyesters are used which contain the constituents to formula VIII.
32. A method according to at least one of claims 28 to 31, characterised in that spinning is conducted at a melting temperature in the range from 210 to 250°C.
33. A method according to at least one of claims 28 to 32, characterised in that the monofilaments are drawn off at a draw-off speed of 5 to 30 m/min.
34. Use of the monofilaments of claim 1 for or during the production of flat textile structures of high mechanical and chemical resistance.
35. Use of the monofilaments of claim 1 for or during the production of paper mesh filters.
36. Use of the monofilaments of claim 1 for or during the production of spiral filters.
37. Use of the monofilaments of claim 1 for or during the production of screen printing fabrics.
38. Use ofthe monofilaments of claim 1 for the production of industrial filter fabrics.
39. Use of the monofilaments of claim 1 for or during the production of conveyor belts.
40. A flat textile structure of high mechanical and chemical resistance, characterised in that it contains or consists of core/sheath monofilaments according to claim 1.
41. A paper mesh filter characterised in that it contains or consists of core/sheath monofilaments according to claim 1.
42. A spiral filter characterised in that it contains or consists of core/sheath monofilaments according to claim 1.
43. Screen printing fabric, characterised in that it contains or consists of core/sheath monofilaments according to claim 1.
44. Industrial filter fabric characterised, in that it contains or consists of core/sheath monofilaments according to claim 1.
45. A conveyor belt, characterised in that it contains or consists of core/sheath monofilaments according to claim 1.