Monofilaments having high abrasion resistance and dimensional stability and low slide friction, textile fabrics composed thereof and use thereof

Abstract

Monofilaments having high abrasion resistance and dimensional stability and low slide friction, textile fabrics composed thereof and use thereof Disclosed is a polyester monofilament comprising a) 60 to 85 wt.-% of a polyester raw material selected from the group of polyethylene terephthalate, of polyethylene naphthalate, of to polyethylene terephathalate modified with dicarboxylic acid, of polyethylene naphthalate modified with dicarboxylic acid, or of combinations thereof, b) 14.4 to 30 wt.-% of a thermoplastic elastomeric block copolymer, c) 0.05 to 10 wt.-% of a polycarbonate, and d) 0.1 to 10 wt.-% of a carbodiimide stabilizer, wherein the quantities are based on the total amount of the monofilament. The disclosed monofilaments can be preferably used for the manufacture of paper machine clothing and are distinguished by high hydrolytic stability, abrasion resistance and dimensional stability as well as by a very low slide friction.

Claims

1. A polyester monofilament containing a) 60 to 85 wt. % of a polyester raw material selected from the group of polyethylene terephthalate, of polyethylene terephathalate modified with dicarboxylic acid, or combinations thereof, b) 14.4 to 30 wt. % of a thermoplastic elastomeric block copolymer selected from thermoplastic polyurethane elastomers and thermoplastic polyester elastomers, c) 0.05 to 10 wt. % of a polycarbonate, and d) 0.1 to 10 wt. % of a carbodiimide stabilizer, wherein the quantities are based on the total amount of the monofilament, wherein the monofilament exhibits improved abrasion resistance as compared to the same polyester monofilament having components a) and b) in the recited amounts prepared without both polycarbonate and carbodiimide stabilizers in the recited amounts.

2. The polyester monofilament according to claim 1, wherein component a) is a polyethylene terephthalate.

3. The polyester monofilament according to claim 1, wherein component a) is a polyethylene terephthalate modified with dicarboxylic acid.

4. The polyester monofilament according to claim 3, wherein the polyethylene terephtalate modified with aromatic dicarboxylic acid is a polyethylene terephthalate modified with isophthalic acid or a polyethylene terephthalate modified with phthalic acid.

5. The polyester monofilament according to claim 3, wherein the polyethylene terephtalate modified with aliphatic dicarboxylic acid is a polyethylene terephthalate modified with adipic acid or a polyethylene terephthalate modified with sebacic acid.

6. The polyester monofilament according to claim 1, wherein component b) is a thermoplastic polyester elastomer.

7. The polyester monofilament according to claim 1, wherein the monofilament exhibits improved abrasion resistance of at least 48% as compared to the same polyester monofilament having components a) and b) in the recited amounts prepared without both polycarbonate and carbodiimide stabilizers in the recited amounts when tested as the back weft of a multilayer forming fabric.

8. The polyester monofilament according to claim 1, wherein component c) is a polycarbonate that is derived from bisphenols.

9. The polyester monofilament according to claim 1, wherein component d) is a polymeric carbodiimide.

10. The polyester monofilament according to claim 1, wherein the monofilament contains besides components a) to d) in addition 0.001 to 10 wt. % of common additives e), selected from antioxidants, UV-stabilizers, fillers, pigments, biocides, additives for increasing the electrical conductivity, additives for increasing the abrasion resistance, friction reducing additives, avivages, processing aids, plasticizers, lubricants, matting agents, viscosity modifiers, crystallization promoters or combinations of two or more of these additives.

11. The polyester monofilament according to claim 1, wherein this contains component a) in an amount from 70 to 80 wt. %, component b) in an amount from 20 to 25 wt. %, component c) in an amount from 0.5 to 3 wt. % and component d) in an amount from 0.3 to 4.5 wt. %.

12. The polyester monofilament according to claim 1, wherein the monofilament comprises 70.5-79.1 wt. % of PET modified with 10 to 15 wt. % of isophthalic acid, 20-25 wt. % thermoplastic polyester elastomer, 0.5-2.5 wt. % of polycarbonate and 0.4-4.5 wt. % of polymeric carbodiimide.

13. A textile fabric comprising threads according to claim 1.

14. In paper manufacture, a method of of using the polyester monofilament according to claim 1, comprising incorporating the polyester filament into a paper machine clothing and utilizing the paper machine clothing used in a sheet formation section and/or in a dryer section of a paper machine.

15. The textile fabric according to claim 13, selected from a web, a knitted fabric, a mesh fabric or a laid fabric.

16. The polyester monofilament according to claim 1, wherein component b) is a thermoplastic polyester blockcopolymer elastomer-comprising blocks of polybutylene terephthalate and blocks of polyethylene glycol terephthalate.

17. The polyester monofilament according to claim 1, wherein component c) is a polycarbonate that is derived from Bisphenol A.

18. The polyester monofilament according to claim 3, wherein component a) is a polyethylene terephthalate modified with aromatic dicarboxylic acid or a polyethylene terephthalate modified with aliphatic dicarboxylic acid.

19. The polyester monofilament according to claim 18, wherein component b) is a thermoplastic polyester elastomer.

20. A paper machine clothing, a conveyor belt or a filtration screen which comprises a polyester monofilament containing a) 60 to 85 wt. % of a polyester raw material selected from the group of polyethylene terephthalate, of polyethylene terephathalate modified with dicarboxylic acid, or combinations thereof, b) 14.4 to 30 wt. % of a thermoplastic elastomeric block copolymer selected from thermoplastic polyurethane elastomers and thermoplastic polyester elastomers, c) 0.05 to 10 wt. % of a polycarbonate, and d) 0.1 to 10 wt. % of a carbodiimide stabilizer, wherein the quantities are based on the total amount of the monofilament, wherein the monofilament exhibits improved abrasion resistance as compared to the same polyester monofilament having components a) and b) in the recited amounts prepared without both polycarbonate and carbodiimide stabilizers in the recited amounts.

21. A paper machine clothing, a conveyor belt or a filtration screen according to claim 20, which is a multilayer web including back weft monofilament containing a) 60 to 85 wt. % of a polyester raw material selected from the group of polyethylene terephthalate, of polyethylene terephathalate modified with dicarboxylic acid, or combinations thereof, b) 14.4 to 30 wt. % of a thermoplastic elastomeric block copolymer selected from thermoplastic polyurethane elastomers and thermoplastic polyester elastomers, c) 0.05 to 10 wt. % of a polycarbonate, and d) 0.1 to 10 wt. % of a carbodiimide stabilizer, wherein the quantities are based on the total amount of the monofilament, wherein the monofilament exhibits improved abrasion resistance as compared to the same polyester monofilament having components a) and b) in the recited amounts prepared without both polycarbonate and carbodiimide stabilizers in the recited amounts.

22. A paper machine clothing, a conveyor belt or a filtration screen according to claim 21, which is a multilayer web including back weft monofilament in which in the back weft monofilament consists of polyester monofilament containing a) 60 to 85 wt. % of a polyester raw material selected from the group of polyethylene terephthalate, of polyethylene terephathalate modified with dicarboxylic acid, or combinations thereof, b) 14.4 to 30 wt. % of a thermoplastic elastomeric block copolymer selected from thermoplastic polyurethane elastomers and thermoplastic polyester elastomers, c) 0.05 to 10 wt. % of a polycarbonate, and d) 0.1 to 10 wt. % of a carbodiimide stabilizer, wherein the quantities are based on the total amount of the monofilament, wherein the monofilament exhibits improved abrasion resistance as compared to the same polyester monofilament having components a) and b) in the recited amounts prepared without both polycarbonate and carbodiimide stabilizers in the recited amounts and wherein the multilayer fabric exhibits improved abrasion resistance of at least 48% as compared to the same fabric with back weft monofilament consisting of polyester monofilament having components a) and b) in the recited amounts prepared without both polycarbonate and carbodiimide stabilizers in the recited amounts when tested as the back weft of the multilayer fabric.

Description

DETAILED DESCRIPTION

(1) The combination of components a), b), c) and d) used according to the invention awards to the threads in addition to an excellent abrasion resistance good textile technological properties, in particular a very low slide friction and a high dimensional stability combined with an excellent hydrolysis restistance. Especially the very good values for the abrasion resistance and for the low slide resistance were not to be expected for the skilled artisan.

(2) The selection of components a) to d) is carried out by the skilled artisan on an individual basis. So, components a) to d) must be selected in a manner, that their processing can be performed at temperatures in which none of the components is subject to a significant decomposition.

(3) In addition to the above described components a) to d) the polyester monofilament of the invention may contain additional and common additives e). The amount of such components e) is typically 0.001 to 10 wt.-%, based on the total amount of the monofilament.

(4) Examples of common additives e) are antioxidants, UV stabilizers, fillers, pigments, biocides, additives to increase the electrical conductivity, additives for improved abrasion resistance, friction reducing additives, avivages, processing aids, plasticizers, lubricants, matting agents, viscosity modification agents, cristallization accelerators or combinations of two or more of them.

(5) The components a), b), c), d) and e) needed for the production of the threads of the invention are known per se, some are commercially available or can be made by known procedures.

(6) The yarn count of the monofilaments of the invention can vary widely. Examples of this are 50 to 45,000 dtex, especially 100 to 4,000 dtex.

(7) The cross-sectional shape of the monofilaments of the invention can be arbitrary, such as round, oval or n-square, where n is greater than or equal to 3.

(8) The monofilaments of the invention can be produced according to known procedures.

(9) A typical manufacturing process includes the measures: i) mixing of components a), b), c) and d) or of component a) and a masterbatch containing components b), c) and d) in an extruder, ii) extruding the mixture containing components a), b), c) and d) through a spinneret, iii) detracting of the formed monofilament iv) optionally stretching and/or relaxing of the monofilament, and v) winding of the monofilament.

(10) One or more of the components b), c) and d) can be used in the form of a master batch. So, in particular the carbodiimide can be well dosed as a master batch in polyester and mixed into the components of a), b) and c). Also, component b) can be preferably mixed into the components a), c) and d) in the form of a master batch.

(11) The monofilaments of the invention are one or several times stretched during their formation.

(12) Especially preferred as component a) for the production of monofilaments is a polyester raw-material produced by solid phase condensation.

(13) After melting and pressing of the polymer melt through a spinneret, the hot polymer thread is cooled down, preferably in a water bath, and is then stretched one or several times, is optionally fixed and rewound, as it is known from the prior of art for the aforesaid melt-spun polyesters.

(14) Preferably the monofilaments of the invention are used for the production of textile fabric constructions, in particular of fabrics, spiral cloth, laid fabrics or knittings. These textile fabric constructions are preferably used in screens.

(15) The invention therefore relates also to a textile fabric containing the monofilaments described above, especially a textile fabric in the form of a fabric, knitting, knitted fabric, mesh fabric or laid fabric.

(16) The monofilaments of the invention can be used in all industrial fields. Preferably they are used in applications, where increased wear and high mechanical stress in hot, humid environments is to be expected. Examples of this are the use in screen fabrics and filter cloths for gas and liquid filters, in drying belts, for example, for the production of food or in particular of paper.

(17) The invention also relates to the use of the above described polyester monofilaments as paper machine clothing, in conveyor belts and as filtration screens.

(18) Preferably the above described polyester monofilaments are employed as paper machine clothing in the sheet formation part and/or in the dryer section of the paper machine.

(19) The present invention is described in more detail by the following examples. These examples serve only to explain the invention and are not to be regarded as a constriction.

EXAMPLES 1-3

(20) Starting raw material was a polyethylene terephthalate modified in the polycondensation with 12 wt.-% of isophthalic acid and with 88 wt.-% terephthalic acid (PET-type 153 from Invista Resins & Fibres GmbH, Hattersheim). To 75.5 wt.-% of the raw material 20.0 wt.-% of a polyester elastomer (TPE-E type E3918 from Heraflex), 4.0 wt.-% of dicarbodiimide (stabilizer KE 9464 from Rheinchemie) and 0.5 wt.-% of polycarbonate (Makrolon 2458 from Bayer) were dosed gravimetrical immediately before the extruder.

(21) The polymeric mixture was molten in the extruder at 250 C. to 270 C., pressed by a gear pump into a spinning pack and then spun into a water bath of 68 C. This was followed by a multiple stretching under heat with thermosetting and then with winding of the monofilaments.

(22) The monofilaments of examples 2 and 3 were produced analogous to example 1.

(23) Composition and the textile values of the obtained monofilaments are specified in table 1 below. The machine data for the production of the monofilament of example 3 are indicated in table 2 below.

(24) TABLE-US-00001 TABLE 1 monofil monofil monofil example 1 example 2 example 3 diameter (mm) 0.352 0.350 0.350 PET-type 153 (wt.-%) 75.5 70.5 75.2 TPE-E type E3918 20.0 25.0 20.0 (wt.-%) stabilizer KE 9464 (wt.-%) 4.0 4.0 4.0 Makrolon 2458 (wt.-%) 0.5 0.5 0.8 yarn count (dtex) 1238 1248 1237 spec. tenacity (cN/tex) 19.5 17.8 20.7 elongation at break (%) 76.1 115.6 65.9 reference extension at 47.0 93.6 33.3 15 cN/tex (%) reference extension at 20 79.8 60.5 cN/tex (%) thermoshrinkage 6.25 6.8 5.66 160 C./30 (%) thermoshrinkage 12.8 13.9 10.4 180 C./30 (%) secant modulus (GPa) 4.8 4.3 5.3 Young-modulus (kg/mm.sup.2) 489.5 438.9 546.0 knot strength (cN/tex) n.b. n.b. n.b. loop strength (cN/tex) n.b. n.b. n.b. max. shrinking force 164/24.91 70/16.7 173/33.3 ( C./cN) shrinkage at 180 C. (%) 3.67 1.1 4.8 spec. viscosity in 1163 1159 n.b. dichloroacetic acid

(25) TABLE-US-00002 TABLE 2 Machine data for the monofil of example 3 stock temperature extruder 245-256 C. stock temperature spinning pack 253 C. pressure at spinning pack 8.8 MPa water temperatures spinning bath 68 C. stretching bath 1 90 C. stretching bath 2 90 C. air temperature fixing channel 225 C. stretching ratios stretching unit 4:stretching unit 1 3.869:1 stretching unit 4:stretching unit 2 1.0714:1 stretching unit 4:stretching unit 3 0.938:1 velocity stretching unit 4 150.1 m/min

COMPARISON EXAMPLES OF V1 TO V8 AND EXAMPLES 4 to 6

Testing of Abrasion Resistance

(26) Monofilaments were prepared analogous as described in example 1. Composition and quantities of components used in the production, as well as the abrasion values determined for these monofilaments are listed in the following table 3. Polymer throughput and stretching were chosen in a manner, so that monofilaments with a diameter of 0.25 mm were obtained.

(27) These monofilaments have been tested as 100% in the back weft of multi-layer forming webs of identical construction. The abrasion test was performed in 2000 in an analyzer Einlehner AT 2000. The following test conditions have been used:

(28) suspension used: 1% CaCO.sub.3 (Omya HC40BG) in 99% water not tempered, at the beginning of the test about 25 C.

(29) friction body: Al.sub.2O.sub.3

(30) wrap angle: 180

(31) run length: 25,000 m

(32) prestretching weight: 2000 g

(33) fabric strip width: 25 mm

(34) The decrease of the web thickness in m is indicated as abrasion.

(35) TABLE-US-00003 TABLE 3 poly polymeric car- carbo- exam- polyester.sup.1) TPE-E bonate diimide abrasion ple (wt.-%) (wt.-%) (wt.-%) (wt.-%) (m) remarks V1 100 102 100% PET as comparision V2 75 25 106 V3 74.5 25 0.5 96 influence of V4 74.2 25 0.8 90 polycarbonate V5 73.8 25 1.2 86 V6 73 25 2 95 influence of V7 71 25 4 87 carbodiimide V8 69 25 6 85 4 70.5 25 0.5 4 44 influence of 5 70.2 25 0.8 4 42 the combi- 6 73.8 25 1.2 4 41 nation of poly- carbonate and carbodiimide .sup.1)polyethylene terephthalate PET was used in comparative example V1; polyester of the PET type 153 was used in the other comparative examples and in the examples in table 3.

(36) The marked improvement in abrasion resistance by using the monofilaments of the invention is surprising. For the variants of the multi-layer forming fabrics according to the invention 41 to 44 m abrasion were detected compared to 85 to 96 m abrasion by using monofilaments stabilized only by polycarbonate or only by carbodiimide or 102 to 106 m abrasion by using monofilaments consisting only of polyester.