EP0748402B1 - Process for producing a polyester weft yarn for tyre fabric - Google Patents

Description

The invention relates to a process for continuous Manufacture of a multifilament, stretchable weft yarn Polyester POY filaments for tire cord fabric, as well as a weft yarn produced by the process.

Is under a polyester POY (partially oriented yarn) a from 2800 to about 4200 m / min by melt spinning from Understand polyester-made yarn.

Process for the production of weft yarns for tire cord fabrics, which has a rough, non-slip surface have and the high thermal and mechanical Loads during tire production are sufficient known. In addition to the processes for the production of coated Weft threads are also processes for the production of uncoated polyester wefts known. Both known method, the sliding resistance is either by winding with natural fibers or by twisting a thread made of polyester POY and subsequent heat treatment (EP-A-0 223 301). A wrap yarn leads to an unacceptable on air jet machines Fiber flight. A twisted, stretchable weft yarn is in at least two production stages technically complex would produce an additional swirling add another step to complex procedures. The possibility of one carried out in the winding area Whirling is called in the prior art, however, a process for technical action is not specified. The combination of twisting / twisting is in itself senseless because a poorer method of achieving one Thread closure combined with a better and thus the first step of the process becomes superfluous. A reversal of steps, i.e. Twisting / swirling does not make sense since a twisted and therefore largely closed Thread bundle can only be swirled insufficiently.

If the swirling is done alone, it usually takes place before winding, d. H. after completing all other process steps take place. In the present case, swirling shrunken POY, this leads Process to an inhomogeneous yarn with many protruding Filament sheets that ensure a perfect bobbin drain hinder.

The object of the invention is a technically simple and economical process for producing a highly stretchable Polyester weft yarn for tire cord fabric for To make available.

Another task is to use a weft yarn with a to provide high elongation, even after an extreme thermal load is preserved. At the same time, the yarn should have a very low thermal shrinkage and the longest possible run length per Have unit of weight.

According to the invention, this object is achieved in that the polyester POY filament with an initial titer of swirled dtex 170-260 with a compressed gas and immediately afterwards with a lead of 40-80% 230-240 ° C is shrunk.

The titre range from 170-260 dtex, especially 170-210 dtex, preferably 170-190 dtex, has proven to be special proven to be advantageous since titer over 260 dtex from weaving technology Reasons for tire cord are poorly suited and require too much force at 80% elongation. In corduroy the threads must lie as flat as possible so that the chain / weft crossing points are not undesirable Surveys occur during dip treatment be coated unevenly. With a titer below The tear strength RK is too low and the reversibility limit is 170 dtex insufficient. It has gone further than Proven to be a heat treatment immediately after swirling, whereby at Temperatures below 230 ° C an insufficient shrink release and above 240 ° C already damage the Polymer enters. At the same time there is an advance of 40-80%, especially from 50-70% appropriate.

It is also appropriate to swirl in a swirl nozzle, especially in a closed swirl nozzle at 0.5-3, especially at 1-2 bar to make. In an open swirl nozzle is at the low thread tension (only the outlet tension) and the applied pressure a safe swirl not always guaranteed as the filaments come out of the nozzle can be blown. At a pressure below 0.5 bar insufficient thread closure is achieved. At a Pressure above 3 bar the thread closure is not improved, however, damage to the Filaments on.

Heat shrinkage is convenient at 220-235, in particular at 230-235 ° C for a minimum of 0.2 seconds, preferably in a convection heater carried out. This has the advantage of a reversibility limit greater than 3 cN / tex results and a sufficient Roughness or sliding resistance is guaranteed.

Experience has shown that high stretch weft yarns made of shrunk polyester POY at a subsequent one thermal stress such as cord fabric when impregnating be subjected to elongation. This Elongation can lead to uneven cord fabrics, which can cause difficulties in further processing. In such cases, it is advisable to add the weft manufacturing in a further, in particular integrated process step directly after the Shrinking at a temperature of 100-200 ° C, especially 110-170 ° C by 1-5% and then wind up.

The weft yarn according to the invention is sufficient at the same time following conditions: the surface of the weft is rough and slip resistant, the tear resistance Ft> 7cN / tex, Elongation Dt 170-270%, and the thermal shrinkage TS (at 160 ° C) in Range + 2% - minus 2%.

It is useful if the number of knots is more than 25 knots / m is. The fibril bandage is less than 25 knots / m not sufficiently compact, causing run-off problems and dipdepots can arise.

After a tension-free heat treatment at 235 ° C, for 2 minutes, the weft has a residual stretch of at least 110% and a thread elongation of less than 5%.

The invention will be described in more detail using examples become.

example 1

Starting from a polyester POY melt spun at 3100 m / min dtex 170f72 is between a gate and a first delivery plant with 2 bar in a closed Swirl nozzle (2x1.2 mm) swirled and immediately then with an advance of 60% at 230 ° C shrunk and then at room temperature or Stretched 160 ° C.

Example 1 shows the properties of the yarn according to the invention after shrinking without and with 5% post-stretching. Examples 2-4 relate to the production conditions according to the invention without post-stretching. Master thread: dtex 170 f72 Swirl: 2 bar
Lead: 60% Post-stretch variant. without setting zone - with setting zone cold 5% with setting zone 160 ° C 5% Titre dtex 266 253 259 RK cN 181 183 189 Ft cN / tex 6.8 7.2 7.3 Dt% 242.6 229 232.8 TS 160% -1.7 .35 1.8 TS 190% -2.7 -.7 1.5 After thermal test treatment 235 ° C, 2 min Delay variant without setting zone - with setting zone cold 5% with setting zone 160 ° C 5% RK cN 209 215 207 Ft cN / tex 7.9 8.5 8.0 Dt% 156.5 157 149.7 Elongation% -4.7 -2.75 -.45

Example 2

Polyester-POY master thread: dtex 190f36
Swirl pressure: 1bar Advance% 20th 40 60 80 100 Titre dtex 239.10 280.80 321.60 359.90 399.40 RK cN 270.66 273.22 296.52 321.03 343.88 Ft cN / tex 11.32 9.73 9.22 8.92 8.61 Dt% 145.60 186.50 231.00 261.20 292.30 TS 160% 0.20 -1.20 -1.80 -1.60 0.00 TS 190% -0.70 -2.70 -3.40 -3.60 -1.30 Titer increase% 20.30 41.25 61.8 81.03 101.90 Reverse. Limit cN / tex 5.1 4.4 4.0 3.7 3.72 after 2 min at 240 C. Titre dtex 239.10 280.80 - 359.90 399.40 RK cN 267.55 273.22 - 309.87 330.30 res. RK% 98.85 100.00 - 96.52 96.05 Ft cN / tex 11.19 9.73 - 8.61 8.27 Dt% 108.90 128.50 - 169.20 197.40 Change in length% -0.20 -3.80 - -4.80 -3.20 Reverse. Limit N 1.24 1.35 - 1.55 1.63

Example 3

Master thread: dtex 190f36 Swirl pressure: 2bar Advance 20th 40 60 80 100 Titre dtex 243.90 278.60 317.90 358.90 399.80 RK cN 215.61 239.87 293.10 321.93 343.43 Ft cN / tex 8.84 8.61 9.22 8.97 8.59 Dt% 124.40 172.30 225.50 259.70 288.50 TS 160% 0.30 -1.10 -1.50 -0.20 1.40 TS 190% -0.50 -2.70 -3.50 -2.50 -1.00 Titer increase% 22.70 40.14 59.90 80.50 101.10 Reverse. Limit cN / tex 4.8 4.4 3.9 3.6 3.4 after 2 min at 240 C. Titre dtex - 278.60 317.90 358.90 399.80 RK cN - 261.88 290.56 322.65 351.42 res. RK% - 109.18 99.13 100.22 102.33 Ft cN / tex - 9.40 9.14 8.99 8.79 Dt% - 116.50 147.20 179.40 215.40 Change in length% - -3.40 -4.70 -3.20 0.20 Reverse. Limit N - 1.35 1.51 1.61 1.69

Example 4

Polyester-POY master thread: dtex 260f48 intermingling pressure: 2bar Advance 20th 40 60 80 100 Titre dtex 333.70 377.30 426.80 478.30 532.90 RK cN 305.34 345.23 384.55 431.90 461.49 Ft cN / tex 9.15 9.15 9.01 9.03 8.66 Dt% 112.70 155.50 200.20 238.90 274.30 TS 160% -1.50 -3.20 -4.00 -3.20 -2.20 TS 190% -3.00 -5.60 -5.70 -5.50 -3.60 Titer increase% 27.40 44.00 62.90 82.60 103.30 Reverse. Limit cN / tex 4.6 4.2 3.8 3.5 3.1

The weft yarn according to the invention has, in addition to the single-stage the process whereby swirling, shrinking and Post-stretching continuously in one process step be carried out, especially a strong reduction the tendency to elongate after additional heat treatment 235 ° C, which makes it excellent suitability of a weft yarn for use in tire construction. It is surprising that the roughness, or the sliding resistance can be achieved without twisting or coating can. After the twisting incident, can be caused by a additional hot stretching the disadvantageous elongation be significantly reduced.

Claims (7)

1. Process for continuous production of a multifil extensible weft yarn from polyester POY filaments for tyre cord fabric, characterized in that the polyester POY filament having a starting linear density of 170-260 dtex is entangled using a compressed gas and immediately thereafter shrunk at 230-240°C using an overfeed of 40-80%.
2. Process according to Claim 1, characterized in that the entangling takes place in an entangling jet at a pressure of 0.5-3 bar.
3. Process according to Claim 1, characterized in that the heat shrinking is carried out at 220-235°C in a convection heater for at least 0.2 s.
4. Process according to Claim 1, characterized in that the weft yarn is continuously post-stretched by 1-5% at 100-220°C in a further integrated process step.
5. Polyester weft yarn produced by the process of Claims 1-4, characterized in that the weft yarn satisfies the following conditions simultaneously: that the surface of the weft yarn is rough and slippage-resistant, the strength > 7 cN/tex, elongation of 170-270% and has a thermal shrinkage (at 160°C) of + 2% - minus 2%.
6. Weft yarn according to Claim 5, characterized by a node count of at least 25 nodes/m.
7. Weft yarn according to Claim 5, characterized by a residual elongation of at least 110% following a tension-free heat treatment at 235°C for 2 minutes and by a lengthening of less than 5%.