DE2023526A1 - Process for the production of low-shrinkage polyester threads - Google Patents

Description

FARBrtSBICE HOECHST AG. formerly Master Lucxus & Brüning File number: _ HOE 7o / F ö76

r ψ

Date: May 12, 1970 - Dr.v.F./Ga

"Ancestors ^ ur production of low-shrink polyester threads"

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The invention relates to a method for producing from high molecular weight linear polyesters of high-strength threads with low elongation and shrinkage values after the spin-draw process.

The production of high-strength, low-stretch polyester threads is described many times. Practically every drawing process which allows a high-strength polyester thread to be heated leads to low-stretch threads, but the high tendency to shrink when heated demonstrate. Such threads can be produced, for example, in that the threads wound into bobbins after the spinning process unwound and then stretched with the application of heat. This stretching can take place in one or more stages; Heat can be applied by heated rods, plates, rollers, liquids or gases.

There are also known methods in which the thread directly from the spinneret to take-off elements and from there to further stretching is fed. With these spin-drawing processes, the thread speeds are usually several times higher than with the first-mentioned method, since for economic reasons the spinning speed should not be too low. Here too the stretching takes place via heat transfer media, whereby often "heated, driven rollers (godets) are used. The threads obtained after working this procedure are due to. Due to their low elasticity, they are well suited for ropes and cordage, but would shrink at higher temperatures and therefore for many other technical articles may be unsuitable. *

Also known is a method for producing tire cord, threads made of polyethylene terephthalate, according to which the melt

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spun thread without intermediate storage over heated godets in two stages is drawn, the temperatures of the second drawing godets be kept in the range of 180 ° to 225 ° C. Such threads have elongations at break, as they are for use as Insert can be used in car tires; whose tendency to shrink is but too big for that. One is therefore forced by a Nachfoigaxfe

single or multi-stage thermal treatment at temperatures up to to thermoset the thread at 22o C »

The production of low-shrinkage polyester threads is also known. The simplest and oldest method is to allow the shrinkable threads to shrink freely, discontinuously or continuously, at or above a temperature to which they will later be exposed. However, this treatment is always associated with a strong increase in elongation at break and a decrease in specific strength. Be in a manner fully shrunk threads or articles made products at room temperature stretched and then relaxed again, enters a permanent elongation a "makes it impossible to thus produced low-shrinkage threads a dimensionally stable in use technical products _o eg a lashing, V-belts or make a conveyor belt.

In order to counteract the undesirably high increase in elongation when shrinking, special procedures are used for theraofixing. For example, a bekaaatea method is used to produce a thread with high shrinkage in several stages at high Temperatures post-treated, with elongations and reductions on top of each other follow. The temperatures used are for polyethylene terephthalate at a maximum of 232 ° C. The listed thread speeds are 137-594 m / min, the dwell time in which the thread is exposed to the fusing temperature and shrunk is two Seconds. .

In another method, the heat-setting of a shrinkable thread is carried out in a fluidized bed formed from small solid particles, with relaxation at temperatures in the range from 251 ° to 264 ° C. for a setting time of 1 ... to 12 seconds

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BATH

and a thread speed of 5Go m / min is used. Furthermore, a method for producing high-strength polyester threads with low shrinkage and elongation at break between 12% and 20% is described. A spun thread is stretched over heated godets and shrunk onto heated godets. The stressed surface temperatures of the drawing godets are between 1
150 m / min.

between 15o to 23o ° C, the Fadengesehwindxgkeiten are up to

Furthermore, a method is known according to which the threads after multi-stage stretching under a tension of 3 p / tex are wound up. Threads produced in this way show a number of excellent ones textile properties, but the shrinkage values are unsatisfactorily high for many purposes.

The threads produced by this process must therefore be in a separate step according to other known methods, for example be thermoset in a fluidized bed.

The following steps are therefore necessary to produce high-strength polyester threads with low thermal shrinkage and low elongation necessary: spinning - drawing - heat setting (shrinking).

The known process for the production of from high molecular weight linear polyesters existing threads with low elongation and shrinkage values have the disadvantage that an interruption of the Process is required at one or two points between these three manufacturing stages. The thread speeds are with the known thermosetting process with a maximum of 600 m / rain relatively low; If the stretching is combined with the heat setting as described above, the result is even lower ones Speeds. The processes described so far do not allow spinning, drawing and heat setting to be carried out continuously in this way combine that, on the one hand, a high production speed is achieved and, on the other hand, low-stretch and low-shrinkage, high-strength threads are obtained will.

The method according to the invention is intended to be used in one operation and high-strength threads with high thread running speeds

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high molecular weight, linear polyesters after the spin-drawing process to manufacture. The resulting threads have low elongation and shrinkage values.

According to the invention, based on the known methods, these objects are achieved in that, after drawing, the threads o, o2 until o.5 see. via godets with surface temperatures of 23o to 28o ° C and then relaxed under a tension of 0.2 to Io p / tex.

Surprisingly, those produced by this process show Threads have a low one despite the extremely short shrinking times Thermal shrinkage and low elongation at break. The inventive Process can be carried out at winding speeds which are two to six times higher than those previously known Process for making such threads.

According to the process according to the invention, high-strength polyester threads with low thermal shrinkage and low elongation at break are produced from linear polyesters. These linear polyesters are made from dicarboxylic acids and glycols. As dicarboxylic acid, for example, terephthalic acid, isophthalic acid, 4,4'-diphenyldicarboxylic acid, 2,5-dimethylterephthalic, 5-sulfo-isophthalic acid, bis (p-carboxy-phenoxy) -ethane, naphthalenedicarboxylic acid (1.3), - (1.4) , - (1.5), - (2.6), hexahydroterephthalic acid, cyclobutanedicarboxylic acid, adipic acid, suberic acid, sebacic acid, decanedicarboxylic acid and sulfonyl-4,4-dibenzoic acid or their ester-forming derivatives or mixtures thereof, use as diols, for example, aliphatic diols such as xthylene glycol, 1.2 ), Butanediol (1.4), 2,2-dimethylpropanediol (1.3), cycloaliphatic diols such as cyclobutanediol (1.2) and cyclobutanediol (1.3) and 1,4-dimethylolcyclohexane and aromatic-aliphatic diols such as 1.3- and 1.4-xylylene glycol or bis- ( 4.4'-hydroxyphenyl) dimethy! Methane, 1.3 _r and 1.4-bis-hydroxyethoxybenzene or mixtures thereof.

Polyäthylenterephthalat.Bei is preferably used as the polyester In polyester production, up to 1 percent by weight, based on the polymer, of branching components can also be used be, for example trimellitic acid, trimesic acid, pyromellitic

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acid, 5-hydroxyisophthalic acid or pentaerythritol, trimethylolethane- (1.1.1), Trimethylolpropane- (1.1.1), 1.1.4.4-tetramethylolcyclohexane, 2.2.6.6-Tetramethylol-cyclohexanol- (l) or their Polyester-forming derivatives.

The usual additives, such as matting agents, UV stabilizers and the like, are also incorporated into the polyester. The polyester are produced according to the usual processes and spun into threads from the usual systems using the melt spinning process. That Spinning, stretching, fixing and winding are therefore carried out continuously in one operation. .

The attached figure explains the method according to the invention. After the polyester melt has been pressed out of the spinneret S, the thread is cooled in the usual way on a preparation roller P provided with a spin finish and then repeated several times a pair of godets 1, which · a surface temperature of 80 ° τ 12o ° C from Aveist, looped. With the help of this pair of godets on the one hand, the take-off speed is determined, which can be between 200 and 800 m / min; on the other hand, the thread is warmed up to the drawing temperature. The thread is now the pair of godets 2, which has a surface temperature of 12o ° to 22o ° C and a circumferential speed 3.5 to 5.5 times higher has a pair of godets 1. (The stretching already relies on the last wraps of godet pair 1 and is already essentially finished before the thread hits godet pair 2.) After looping around the pair of godets 2 one or more times the thread on a pair of godets-3, which surface temperatures between 23o ° and 28o ° C and its peripheral speed 4.5 to 7 times larger than that of the pair of godets 1. Although the polyethylene terephthalate threads melt at temperatures above 26o ° C, With the applied method, the surface temperature can be 26o C and above, because because of the short contact time between threads and godets, the former obviously does not match the temperatures of the Reach godets, post-drawing takes place between godet pairs 2 and 3, (i.e. the thread already has essentially the circumferential speed, des Pair of godets 3.). The pair of godets 3 is now one or more times

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wrapped around in order to obtain contact _{times of the thread from o t} o2 to o.5 see with the godet surface, the thread then under a tension of o _? 2 to Io p / tex (based on the final titer) a further pair of godets 4, which is unheated, and then fed to a conventional winding. It is also possible not to loop around the pair of godets 2 completely, but rather to guide the thread only over a single rotating godet "whose surface temperature is 12o-220 ° C, with a quarter" to half a loop. The rotating single godet can also be replaced by a plate heated to 12o -22o ° C.

The thread can also go directly from the pair of godets 1 to the pair of godets 3, the thread being heated to 175 to 45o C by a flow of hot steam before it reaches the pair of godets 3 can be. It is also possible to run the thread directly after godet pair 3 with a tension of 0.2 to 5 p / tex one to supply conventional winding, but it is advantageously ensured that it is previously blown with air, sprayed with Preparation or the like is cooled. The winding speeds can vary depending on the take-off speed and draw ratio between 1200 and 35oo m / min.

The threads touch the pair of godets 3, which is heated to 23o-28o ° C, for 0.02 to 0.5 seconds. If the temperature of the pair of godets 3 is lowered to below 23o ° C., in order to still obtain threads with the desired properties, the relaxation tensions would have to be so small that the process would no longer be operationally reliable. The threads would then run very restlessly and over one another on the godets, which would result in thread breaks. Temperatures above 280 ° C. are also not recommended for the pair of godets 3, since at these temperatures softening of the polyester threads is to be expected even at the running speeds used according to the invention. The threads touch the heated godets 3 for 0.02 to 0.5 sec, depending on the number of loops around the godet pair 3. After contact times of more than ₅ O 5 see the resulting Fädea no longer have the desired properties, in particular "could at high temperatures of the pair of godets 3 is not the desired Festigkeiten- be achieved more; '

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The dwell time on the godets depends on allPV used Temperature of the godet surface, the surface properties of the Galette, the titer of the thread to be produced and the surface properties this thread off. The lower limit of the dwell time is can therefore be used at high temperatures and low titers »also in processes in which, due to the nature of the surface the godet and the threads there is such a high friction between the thread and godet that it is possible with a looping only to avoid a slippage of the thread. With high titers, smooth threads and godets and also with particularly strong ones It is tension differences before and after the pair of fixler godets 3 necessary to apply the range of the upper limit of the dwell time .. From the heated godet pair 3, the threads are under a tension j from ο, 2 to Io p / tex (based on the final titer) on the unheated Pair of godets 4 out. Then a normal winding closes at. The tension between the pair of fixing godets 3 and the pair of discharge godets 4 or the winding depends on the one hand on which heat setting or which residual shrinkage of the fixed Thread is sought, on the other hand of the applied surface temperature of the fixing godets. The lower limit of the voltage results arise from the technical difficulties that arise when at high speed the thread is looped too loosely around the godet, because then the formation of laps on the godet increases Malfunctions. On the other hand, if the relaxation tensions are increased via Io p / tex, based on the final denier of the threads, the Threads no longer have the low shrinkage according to the invention. At the top The range of the specified voltages will be used, for example, if only partial fixation is required. This is the case, for example, if the threads or threads or fabrics made from them, subsequently in a known manner with a rubber latex, a resorcinol-formaldehyde precondensate and a blocked isocyanate to enable adhesion to rubber. To cure this With the adhesive film, the threads or fabrics are exposed to even higher temperatures, and the polyester is also subsequently fixed can. In such processes, such tensions are often applied to the threads or tissue that prevent them from relaxing an undesirable increase in elongation at break occurs. When using originally unfixed threads, the residual shrinkage would be the

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armored fabric or threads would then be too high and cause difficulties in the subsequent vulcanization. On the other hand, can If the shrinkage of the finished thread is kept constant, the higher the surface temperature, the higher the tension the fixing godet is. Such options are described in more detail in the examples.

It is surprising that it succeeds in doing the same in such a short time To achieve heat setting, as can be obtained by the previously known methods only after relatively long residence times is. As is well known (see Ludewig "About the Shrinkage Ratios of polyester fibers and silks ", fiber research and textile technology 11 (196o), pages 15-21), a final heat stabilization occurs (Fixation) only after prolonged exposure to higher temperatures. In the case of discontinuous fixations, fixation times are between 3o and 6o minutes (including heating-up time) the rule. Even with continuous Fixing processes, such as those described in British patent specification 1,142,636, use fixing times between 1 and 12 seconds, although the heat transfer occurs in the fluidized bed is particularly good and very high temperatures are used.

In the claimed process, depending on the fixing temperature used, applied fixing tension, previous degree of stretching and the specific viscosity of the polyester threads with more or less steep force-elongation diagram and more or less low shrinkage values. Through the selection and interaction of Fixing temperature and voltage can be optimal settings regarding Find stretch and shrink properties.

example 1

Polyethylene terephthalate with a specific viscosity of I, o6o (measured on a 1% by weight solution in a mixture of phenol / tetrachloroethane in a weight ratio of 3: 2 at 20 ° C.) it is melted in an extruder and at a rate of 220 g / min through a nozzle spun with 2oo holes. After cooling in a chute, the capillary bundle is provided with a spin preparation. Afterward the thread arrives at the take-off godet pair 1 "which has a circumferential speed of 35o m / min and a surface temperature of 9o C. and is embraced eight times. From here the thread arrives at the pair of godets heated to 15o C at a peripheral speed of 157o m / min and is also wrapped around eight times, with one

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Stretching of 1: 4.5 takes place- In the further course the thread is on the - godet pair 3 with a peripheral speed of 2Ϊ7ο m / min and a surface temperature of 25o C under sub-looping. The godets have a diameter of 23o mm, which means with 8 wraps of 18o ° C for each godet a total · contact length of 5.8 m results. According to the surface velocity the galette of 2170 m / min results in a Contact time of 0.16 seconds. Run under a tension of 2 p / tex the threads onto another pair of godets with a circumferential speed of 2080 bins, which is unheated and is wrapped around six times and come from there under a winding tension of 12ο ρ a winding head.

The thread tension was made with devices like those in the Koch-Satlow "Große's Textile Lexicon, ", page 36o (Deutsche Verlags-Anstalt Stuttgart, 1965), are described, measured.

The threads obtained in this way have a specific viscosity of 0.95, a titer of 100 dtex, a specific breaking strength of 74 p / tex, an elongation at break of 14.5 %, an elongation

ο of lo.3% at 6 kp load and a shrinkage of 4.2 % at 16o C. This measurement is carried out in such a way that a piece of thread of exactly Io m is exposed to a temperature of 16o C for 10 minutes in a circulating air drying cabinet. After hanging out for 16 hours at room temperature, the final measurement is carried out. The loo-fold length difference; based on the original length, represents the shrinkage.

Threads with these properties meet the requirement for low Shrinkage with low elongation and are used, for example, for the production of fabrics for conveyor belts.

In the comparative experiment, a discontinuous process is described, according to which threads with such properties could be produced up to now,

Comparative experiment :

Polyethylene terephthalate with a specific viscosity of I, o6o is melted in an extruder and spun at a rate of 220 g / min through a nozzle with 200 bores. After cooling down The capillary bundle is spun in a chute Mistake. Then the thread, as in the example 1 described, stretched, with the difference that the godet

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couple 3 has a peripheral speed of 2170 m / min and an Obex * ~ surface temperature of only 125 ° C. From here it is wound up under a tension of 3 p / tex. This is a mode of operation as described in USP 3,400,194. The threads produced in this way have a specific breaking strength of 74 p / tex, an elongation at break of 1.6%, an elongation of 7.9 % under a load of 6 kp and a shrinkage of 16.6 % at 160.degree. Such threads are suitable for their ^one particularly low elongation very well for the production of ropes and cordage, but are unsuitable because of their high thermal shrinkage for the production of all products, high in their preparation temperatures required (eg during vulcanization) or higher during their use Exposed to temperatures (e.g. hot goods, car tires, etc.). For use in such articles, the threads must subsequently heat-set or made shrinking poor ^ made below as it may v / ground for "B _o.

According to the British patent 1 142 636, the threads are heat-set in a fluidized bed at a temperature of 252 ° C in such a way that the entry speed of the thread is 600 m / min, the exit speed approx. 58o m / srain (-Relascation of 3%) and the residence time in the hot fluidized bed is approx. 3 seconds. The thread obtained had one. Titer, of XI35 dtex, a breaking strength of 70 p / tex, an elongation at break of 14.2%, an elongation of 0.1% with a load of 6 kp and a thermal shrinkage of 4.6 % at 160 ° C.

The threads produced discontinuously in this way have practically the same textile properties as those in Example 1 described.

The comparative example shows the technical progress made by the claimed method is achieved compared to the conventional method through its fully continuous operation, in particular the surprising fact that with a dwell time different from 0.16 to 3 seconds, the same fixing effect can be achieved,

Example 2

Polyethylene terephthalate is made according to the procedure of the US patent

© AD

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2,829,153 continuously, starting from ethylene glycol
and dimethyl terephthalate to a specific viscosity of 1.32
condensed, the melt fed to a spinning pump and after
Filtration spun over sand through a 200-hole nozzle.

The threads are reheated below the nozzle by a device as described in British patent 1 006 136 so that the thread bundle has a tension of 0.04 p / dtex (based on the denier of the undrawn
Thread). The titer of the undrawn thread is 6,800 dtex. After moistening with a preparation, the thread is laid after the in
Example 1 described method stretched, the temperatures of the pair of godets 3 and the tensions between the pair of godets 3 and 4, as indicated in Table 1, are varied.

1125 16 oo 152o T a b e 1 1 e 1 18o 21 ο 4o ferweil-
since on
ialetten-
) aar 3 (SeC) ¹ Tensions
(p / tex)
between
lalettenpasr
Ϊ and 4 Ver
search 1125 16oo 145o Surface temperature
temperature ( ⁰ C)
of pair of galettes ι
12 3 4 ISo 21o 4o o, 16 5.2 A. 1125 16 oo 138o loo 18o 21o 4o o, 16 2.8 B. 1125 16oo 155o loo 18o 24o 5o o, 16 1.1 C. Peripheral speed
(m / min)
of pair of godets
1 2 3 4 1125 16 oo 153o loo 18o 25o 55 o, 16 5.4 D. 25o 1125 16oo 155o loo 18o 26o 58 o, 16 6.8 E. 25o 1125 16oo 155o loo 18o 25o 55 o, 16 7.2 F. 25o 1125 16oo 155o loo 18o 25o 55 0.08 7.1 G 25o loo o, o4 7.2 H 25o loo 25o 25o 25o '

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T rush 2

Ver
search Breaking strength
kp p / tex 78.9 Titer '
dtex Elongation at break
% Shrinkage at 16o ° C
% A. 8.8 74.4 1115 12.6 13.6 B. 8.7 68.7 117o - 15.4 9, X C. 8.5 81.7 124o 2o, 7 7.2 D. 8.9 So, ο Io9o 12.8 7.3 E. 8.8 78.7 lloo 12.8 7.1 F. 8.7 79.3 Ilo5 13.1 7, ο G 8.8 78.2 lllo 12.7 7.2 H 8.7 1115 13, ο 7.4

Table 2 shows the most important textile technological data for the threads obtained after the tests in Table 1. From it it can be seen that at a surface temperature of the pair of godets 3 of 21o C a shrinkage of 7.2% is only achieved when the tension between godet pairs 3 and 4 is greatly reduced, i.e. a relaxation of 13.8% is allowed after stretching (experiment C). The elongation at break then rises to a very high level Values and the specific strength decrease extremely sharply because of the strong increase in titer. If, on the other hand, you work according to the claim of the invention (experiments D - H), a thread is obtained directly, which has the shrinkage and elongation properties required for a polyester tire cord.

Example 3 ;

Polyethylene terephthalate chips with a specific viscosity of 0.85 are melted in an extruder and spun at a rate of 86 g / min through a nozzle with 50 bores. After cooling in the chute, the thread bundle is fed with a spin finish to the pair of godets 1, which has a circumferential speed of 600 m / min and a surface temperature of 90 ° C. and is looped 6 times. From here, the thread arrives at the pair of galettes 2 with a surface temperature of 180 ° C and a circumferential speed of 21oo m / m and wraps around it. In the further

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The thread is fed to the godet pair 3, which has surface temperatures between 23o C and 28o C and a peripheral speed of 3,000 m / min and wrapped around 3 to 12 times and then under tensions of 0.4-3 p / tex with renewed moistening is fed with a preparation of the winding.

The various process parameters are shown in Table 3, the textlien Values of the threads thus obtained are recorded in Table 4.

T a b e 1 1 e

Ver
search Peripheral speed
m / min
of pair of godets
3 4 279o surfaces
temperature
⁰ C of Gal
chain pair 3 Dwell time
on godets
couple 3 (see) Tension between
Galetian
ten pair 3 u.
4 (p / tex) A. 3ooo 281o 23 ο o, 18 o, 4 B. 3ooo 285o 245 o, 18 o, 8 C. 3ooo 291o 26o o, 18 1.2 D. 3ooo 285o 28o o, 12 1.4 'Ε 3ooo 285o 26o o, 12 1.2 F. 3ooo 26o o, o45 1.2

Tabel

attempt

Breaking strength kp p / tex

Titer dtex

Elongation at break

Shrinkage at 16o C

A.
B.
C.
D.
Έ
F.

1.72 1.83 l, 8o 1.75 4.82 1.79

59.3 64.3 63.2 59.4 62.7 62.8

29o 285 285 295 29o 285

17.1 16.2 15.4 15.8 16, ο 16.8

2.5 2.3 2.4 2, o 2.2 2.4

The example shows, on the one hand, that the heat setting during spinning drawing can be carried out in the relatively large temperature range between 23o ° and 28o C and in each case to threads with approximately leads to the same properties if the relaxation stress is adjusted accordingly changed. A fall below the 23o C limit is for procedural reasons not possible, otherwise chip

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openings would have to be applied to the thread that are very small; the threads would then be very restless and stacked on the godets run, which quickly leads to thread breaks.

Claims (1)

PATENT CLAIM Process for the production of high-strength threads consisting of high molecular weight linear polyesters with low elongation and Shrinkage values according to the spin-draw process, characterized in that that the threads immediately after drawing o, o2 - o, 5 see Guided over godets with surface temperatures of 23o to 28o ° C and then under a tension of 0.2 to Io p / tex be relaxed. 109848/1642 Blank page