EP0390025B1 - Sewing thread made from polyetherketone - Google Patents

Abstract

The invention relates to sewing thread made from a polyether ketone, prepared from multifilament yarn having a filament linear density of from 1.0 to 10 dtex, a breaking extension of 3 to 30% and a boil shrinkage of less than 10%.

Description

The invention relates to sewing thread made from at least one multifilament thread, the twisted individual filaments of which consist of a thermoplastic material.

When sewing technical materials such as tarpaulins, seat covers, glass fabrics, but also leather and plastic, yarns based on polyesters are usually used.

However, such sewing threads have the disadvantage that they melt even at relatively low temperatures, so that they can only be processed with high-speed sewing machines, in particular with automatic sewing machines, where the sewing threads can become very hot when the sewing speed changes abruptly if they have special equipment to have. In addition, polyester fibers are not sufficiently resistant to hydrolysis and solvents for many applications.

Sewing threads made from aromatic polyamide (Kevlar®) have a higher temperature resistance. However, their production is quite complex; in addition, their mechanical properties are determined by the manufacturing process (solution spinning), so that they are variable only within narrow limits and cannot be adapted to changing requirements. In addition, they are very difficult to dye. Such sewing threads have therefore not become very important in practice.

It is known that melted polyether ketones can be spun into fibers and then stretched. A suitable spinning process is e.g. in EP-A-202 082. The multifilament yarns obtained have a wide range of properties. For example, the individual titer is between 2.8 and 100 denier (corresponding to 2.5 to 90 dtex) and the elongation at break can be 15 to 200%. However, there is no statement that sewing threads can be produced from such fibers and which multifilament threads are particularly well suited for this.

The invention was based on the task of developing sewing threads based on thermoplastic which have tear strength, elongation at break and dyeability equal to polyester and are also hydrolysis and solvent resistant and allow high sewing speeds even with modern sewing machines.

According to the invention, this object is achieved in that the thermoplastic is a polyether ketone and the multifilament yarn has a single filament titer (according to DIN 53 830) of 1.0 to 10 dtex, an elongation at break (according to DIN 53 815) of 3 to 30% and a boiling shrinkage ( according to DIN 53 866) of less than 10%.

The sewing threads according to the invention have good mechanical properties, such as tensile strength, modulus of elasticity and elongation at break, and low shrinkage, and also excellent resistance to acids, alkalis and solvents. The good heat resistance, which allows high sewing speeds, is particularly advantageous.

Suitable thermoplastics are polyether ketones, preferably high molecular weight polymers with a relative viscosity, measured 0.5% in 96% sulfuric acid at 25 ° C. of more than 1.0, preferably more than 1.3.

Geeignet sind auch Copolymere, bei denen bis zu 50 % der -CO-Gruppen durch -SO₂-Gruppen oder der

durch

ersetzt sind.Preferred polyether ketones are those with the structural units

Copolymers are also suitable in which up to 50% of the -CO groups by -SO₂ groups or

by

are replaced.

It has been shown that multifilament yarns are particularly suitable for the production of sewing threads which have a single filament titer (according to DIN 53 830) between 1.0 and 10, in particular between 1.5 and 6 dtex and their elongation at break (according to DIN 53 815) 3 to 30%, in particular 5 to 20%. The tensile strength of the yarn (according to DIN 53 815) should preferably be between 4 and 10 cN / dtex. Their shrinkage, measured in boiling water according to DIN 53 866, should be less than 10%, preferably less than 2%. The heat shrinkage at 180 ° C. should preferably be below 20%, in particular below 8%.

The multifilament yarns preferably consist of 10 to 1000, in particular 20 to 300 individual filaments. The multifilament yarns are preferably drawn immediately after the spinning process, the drawing ratio advantageously being between 1.5 and 5. However, the multifilaments can also be brought to the required high strengths and low elongation at break values in a rapid spinning process using high winding speeds.

The sewing threads according to the invention are produced in the usual way from these multifilament threads. The multifilament yarn is twisted, whereby if a single multifilament yarn (single twist) is used, the twist (according to DIN 53 832) should be between α = 30 and 100, preferably between α = 40 and 80 in Z-wire. In principle, such a twisted multifilament thread can already be used as a sewing thread. However, at least 2, preferably 2 to 4 multifilament yarns are preferably twisted to form a sewing thread, the twist for the pre-twist between α _vor = 60 and 110, and the twist for the twist turned counter to the pre-twist should lie between α _aus = 80 and 120. The direction of rotation S / Z is preferred for pre-twisting and untwisting. The ratio of α to α _{from front} is expediently chosen so that the finished sewing yarn is balanced and curl-free.

wobei T/m die Drehungen pro m bedeutet.The twist (according to DIN 53 832) is defined by the equation

where T / m means the turns per m.

The sewing threads according to the invention can receive the usual processing preparations during the spinning process, for example lubricants such as mineral oils, ester oils and alkylene oxide adducts; Emulsifiers such as soaps and ionic or non-ionic surfactants; also antistatic agents such as phosphoric acid esters of ethoxylated fatty alcohols and ethoxylated fatty acid derivatives. They can also be subsequently equipped with paraffins, paraffin waxes or silicone waxes to improve the sliding properties.

A particular advantage of using polyether ketone fibers is that the sewing threads can also be processed without heat equipment.

Examples A. Manufacture of multifilament yarns

und einer relativen Lösungsviskosität von 1,478, gemessen in einer Lösung von 0,5 g Polymer in 100 ml 96 % H₂SO₄ bei 25°C, wurde kontinuierlich einer Schmelzspinnapparatur zugeführt und aufgeschmolzen. Die Schmelzspinnapparatur bestand aus einem Einwellenextruder mit 3 el. beheizbaren Heizzonen, einer elektrisch beheizten Spinndüse mit 30 Löchern vom Durchmesser 0,4 mm, Spinnpumpe (Zahnradtyp), Nacherhitzerzone, Blasschacht und Aufspulvorrichtung.
Die Heizzonen des Extruders und des Spinnkopfes wurden auf eine Temperatur eingestellt, daß die Schmelze eine Temperatur von 415°C erhielt. Der Durchsatz betrug 1,6 kg/Std. Die Fäden passierten einen elektrisch beheizten Nacherhitzer und einen mit Luft betriebenen Anblasschacht. Sie wurden mit einer Aufspulgeschwindigkeit von 850 m/min abgezogen und anschließend im Verhältnis 1:3,0 verstreckt, wobei die Einzugsgalette der Streckvorrichtung auf eine Temperatur von 130°C und die Heizplatte im Streckfeld auf 250°C erhitzt wurde. Die Fäden hatten folgende Eigenschaften: Gesamttiter 109/30 dtex Einzeltiter 3,6 dtex Reißfestigkeit 5,4 cN/dtex Bruchdehnung 11,4 % Kochschrumpf 0,5 % Heißluftschrumpf 3,5 % E-Modul 45,1 cN/dtex
2. Ein Polyetherketon mit den wiederkehrenden Einheiten

und einer relativen Lösungsviskosität von 1,98 wurde in der in Beispiel 1 beschriebenen Apparatur versponnen. Die Temperatur der Schmelze betrug 375°C, die Spinndüse hatte 30 Löcher von jeweils 0,3 mm Durchmesser und die Spulgeschwindigkeit betrug 700 m/min bei einem Durchsatz von 1,2 kg/h. Die gesponnenen Fäden wurden anschließend im Verhältnis 1:2,9 bei Temperaturen von 160 bzw. 210°C heißverstreckt und hatten danach folgende Eigenschaften: Gesamttiter 110/30 dtex Einzeltiter 3,7 dtex Reißfestigkeit 5,9 cN/dtex Bruchdehnung 14,0 % E-Modul . 68,0 cN/dtex Kochschrumpf 2,0 % Heißluftschrumpf (180°C) 5,0 %
1. A polyether ketone with the repeating units

and a relative solution viscosity of 1.478, measured in a solution of 0.5 g polymer in 100 ml 96% H₂SO₄ at 25 ° C, was continuously fed to a melt spinning apparatus and melted. The melt spinning apparatus consisted of a single-shaft extruder with 3 el. Heated heating zones, an electrically heated spinneret with 30 holes with a diameter of 0.4 mm, spinning pump (gear type), post-heating zone, blow chute and winding device.
The heating zones of the extruder and the spinning head were set to a temperature such that the melt reached a temperature of 415 ° C. The throughput was 1.6 kg / h. The threads passed through an electrically heated reheater and an air-operated blowing shaft. They were drawn off at a winding speed of 850 m / min and then stretched in a ratio of 1: 3.0, the feed godet of the stretching device being heated to a temperature of 130 ° C. and the heating plate in the stretching field being heated to 250 ° C. The threads had the following properties: Total titer 109/30 dtex Single titer 3.6 dtex Tensile strength 5.4 cN / dtex Elongation at break 11.4% Boiling shrink 0.5% Hot air shrinkage 3.5% E-module 45.1 cN / dtex
2. A polyether ketone with the repeating units

and a relative solution viscosity of 1.98 was spun in the apparatus described in Example 1. The temperature of the melt was 375 ° C, the spinneret had 30 holes each 0.3 mm in diameter and the winding speed was 700 m / min at a throughput of 1.2 kg / h. The spun threads were then hot drawn in a ratio of 1: 2.9 at temperatures of 160 or 210 ° C and then had the following properties: Total titer 110/30 dtex Single titer 3.7 dtex Tensile strength 5.9 cN / dtex Elongation at break 14.0% E-module . 68.0 cN / dtex Boiling shrink 2.0% Hot air shrink (180 ° C) 5.0%

B. Production of sewing threads

A multifilament yarn according to example A2 is wound in parallel on a high-speed winding machine on disc spools. To produce a triple filament thread, 3 of these disc spools are plugged onto the upper level of a thread-twisting-machine and first provided with a pre-wire in the S direction. In the further course of the thread, the 3 twisted multifilament yarns are folded and twisted three times in the Z direction by means of a ring spindle. For the present example, 700 turns per meter S were selected, corresponding to a pre-wire of α _before = 76. 530 turns per meter 3 Z, corresponding to α _out = 100, were selected for the subsequent unwrapping.

From the filament thread thus produced, dyeing bobbins are then produced on a precision winding machine. Depending on the thermal properties of the polyether ketones, the sewing thread can be dyed using the customary dyeing processes, but at an elevated temperature in the range from 180 ° to 200 ° C.

The thermal properties of this colored sewing thread are exceptionally good due to the high melting point of 334 ° C for polyether ketone and a maximum temperature for continuous loading of 250 ° C. This would make it possible to dispense with special sewing thread equipment. For reasons of better sliding properties when pulling through the thread guide elements of the sewing machine and when pulling into the material, we recommend additional equipment. In this case, silicone-containing waxes or emulsions are applied to the dyed sewing thread via a net roller or other known finishing methods for sewing threads, e.g. Equipment used in the dyeing machine.

The sewing thread produced by this method has excellent sewing properties compared to conventional sewing thread. It was found in a sewing test that the sewing thread according to the invention has twice the length of the seam until breakage compared to polyester filament threads. The significantly better thermal and sewing properties are complemented by excellent hydrolysis resistance and resistance to chemicals, e.g. Hydrochloric acid, sulfuric acid, nitric acid, potassium hydroxide solution and trichlorethylene.

Claims (6)

1. A sewing yarn comprising at least one multifilament yarn whose twisted individual filaments are made of a thermoplastic polymer, wherein the thermoplastic is a polyether ketone and the multifilament yarn has an individual filament linear density (as defined in German Standard Specification DIN 53 830) of from 1.0 to 10 dtex, an elongation at break (as defined in German Standard Specification DIN 53 815) of from 3 to 30% and a boil shrinkage (as defined in German Standard Specification DIN 53 866) of less than 10%.
2. A sewing yarn as claimed in claim 1, wherein the polyether ketone is a high molecular weight polymer having a relative viscosity, measured at 0.5% strength in 96% strength sulfuric acid at 25°C, of more than 1.0, preferably more than 1.3.
3. A sewing yarn as claimed in claim 1, wherein the polyether ketone contains at least 50% of the structural units

   
4. A sewing yarn as claimed in claim 1, wherein the multifilament yarn comprises from 10 to 1000, preferably from 20 to 300, individual filaments.
5. A sewing yarn as claimed in claim 1, comprising a single multifilament yarn where the twist factor for the mutually twisted-together individual filaments (as defined in German Standard Specification DIN 53 832) is within the range α = 30-100.
6. A sewing yarn as claimed in claim 1, comprising at least two multifilament yarns where the twist factor for the preliminary twist of the individual multifilament yarns (as defined in German Standard Specification DIN 53 832) is within the range α_pre = 60-110 and the twist factor for the folding twist of the mutually folded-together multifilament yarns (as defined in German Standard Specification DIN 53 832) is within the range α_fold = 80-120, and the directions of the preliminary twist and the folding twist are mutually opposite.