DE1934644A1 - Process for the heat treatment of polyester threads - Google Patents

Description

Folder 22025 - Pr.K / He
Case Z / F "21206

IMPERIAL CHEMICAL INDUSTRIES LT Do London »Great Britain

Process for the heat treatment of polyester threads Priority s 80 July 1968 = Great Britain

The invention relates to an improved heat treatment process for the manufacture of filaments from a linear aromatic polyester. The term "linear aromatic polyesters" means melt-spinnable polyesters, mixed polyesters or polyester blends in which at least 90 % of the units are derived from the same aromatic carboxylic acid and the same diol. The expression "threads made of aromatic» polyester "means not only threads in which this aromatic polyester is the single melt-spinnable component, but also multi-component threads which contain at least 50% of such an aromatic polyester»

After melt spinning, such threads are drawn in order to increase their tensile strength and their modulus and their elongation at break and to reduce shrinkage = However, these properties also depend on the subsequent heat treatments ab »The module can be increased by

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that hot stretching is carried out under high tension, and a reduction in shrinkage can be achieved by carrying out hot relaxation in the de-energized state. A compromise between the increased modulus and the decreased shrinkage can be made by a controlled heat treatment between the following two Achieve extremes: for example, heating at constant length or relaxing with little tension and a small reduction in length ο It is also known to combine hot tendon and hot reaming. However, hot stretching is essentially just a continuation of the stretching process, which one or more stages can be made »Below the expression ^! "Heat treatment occurring after stretching" here is one in which no further stretching is undertaken.

It has now been found that if a certain heat treatment, which takes place after stretching, is switched between a stretching process and a hot relaxation process, which is suitable for reducing the thread-ear dump to a desired low value, the Desired low shrinkage in combination with a lower decrease in the module or even an increase in the module can be achieved ο Furthermore, productivity can be increased, since a smaller overall reduction in the thread length is necessary after stretching »to achieve this lower shrinkage« If dsr Module after a «- between = connected process is sufficiently far obarnalfo ds-s Moöuls, which would be obtained in a relaxation process in the absence of such an interim process, then sin such a swischengesahalfeevas process results in a higher module tiaoh cUeseßi relaxation process, the expediency is in de ? Follow such awisohengeschaitete after drawing heat treatment taking place as a "fixation" means "The allowed Vej ri" igar "ng the thread length fo ^ I of such Flxierungsstufs we rl as"pros;? Enfcuale contract-1 on "" bezeichnetρ which also zero s-ain can. Dia percentage

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reduction of the length in a subsequent relaxation stage is referred to as "percentage relaxation",

Oexnäß the invention, a multi-stage is suggested "esterfäden _t after stretching success forming heat treatment process fllr aromatic poly wherein a is * · heat treatment step switched between before a relaxation step at least, wherein said intermediate heat treatment step, the temperature is not less than the previous Verstreclctemperatur and subsequent Relajcetionstemperetur, the voltage is litfher than the voltage of these subsequent Relaxationssfcufe and the prosentuale contraction is not greater than J>% and not less than nul3. is, ■

There are dwell times in the fixation and relaxation stages preferred, the ns at least 0.01 seconds and up to go to a value that is still expedient.

It is preferred that the proxtmtui la contraction be substantially

is less than the relaxation percentage. A two-stage heat treatment after stretching is also preferred, in which the contraction is zero or nalvs » au is zero.

When applied to the manufacture of a thread yarn v; ird at least a small amount of stress in the relaxation stage Continuous stretching is also preferred, Pixierungs »and Helaxationsverfahren preferred -

In the application to df.e production of staple fibers, a method is preferred wherein _r is performed, the relaxation step at a voltage which is substantially zero.

In the Anwandung on polyethylene terephthalate is preferred to use a Plxierungstemperatür above 200 ⁰ C -and in particular above 220 ⁰ C sov-ie a Relajcationstemperatur of at least 200 ° C to verw

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It has been found that for streoicte polyethylene terephthalate threads the proportional decrease in the module, which is caused by a single-stage «heat treatment lying behind the stretching Stress is caused roughly by the following expression can be represented:

1.47 - 0.009T + 0.000035T ² + 0.55 logt + 0.066R - 0.009R ² - 0.0393 + S (0.012R - 0.066 logt - O, OOO77T) I.

where T represents the temperature In ⁰ C, t represents the tent in minutes, S represents the tensile strength of the drawn threads before the heat treatment and R represents the percentage reduction in the thread length.

According to the invention, a two-stage heat treatment process for threads, which contain at least 95 % ethylene terephthalate units, is proposed after the stretching, in which process the temperature T, the time t and the percentage contraction R in the first stage are such that the value of the The above expression Z is less than 50 % of that value if T, t and R assume the values of the temperature, the time and the percentage relaxation in the second stage, with at least a certain stress being present in each stage, the temperatures between 100 and 250 ^° C., the contraction and relaxation each make up less than 8% , and the treatment times are between approximately 0.001 and 0.05 min.

If the tension in one relaxation stage is zero, then it is determined that in the absence of a fixation call such a relaxation step causes a proportional decrease in the modulus, which is approximated by the expression s

ψ "'- 0.75 - O, OO25T _r II

can be represented.

According to the invention, a two-stage, post-stretching heat treatment process

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proposed for threads containing at least 95 % ethylene terephthalate, in which process the temperature T, the time t and the percentage contraction R iln of the first stage are such that the value of expression I is less than 50 % of the value of expression II, wherein Tr 1st, the temperature of the second stage, in which the voltage is substantially zero, said temperature is between 100 and 250 ⁰ C, the '.prozentuale contraction is less than 8 #, the fixing time is between about 0.001 and 0.05 min and the free relaxation time is more than 0.05 min.

The modules referred to above were determined by stretching a thread at a rate of 10 % elongation per minute and by determining the tension at an elongation of 5 °

In the above drawing process, which can be integrated with melt spinning, any known device can be used or measures are used, such as brake pins, heated rollers, heated plates, immersion in liquids, Treatment by blasting or bathing with a fillable Medium, treatment with turbulent jets or asymmetrical treatments «The heat setting can be integrated with the stretching or carried out separately» It can be regulated by either a {control « adjusted tension or a controlled change in length that may be zero, and it may involve heating the filaments by known means, e.g. Contact with heated solids; "Liquids or Damping or absorption of radiant energy. The relaxation can be carried out continuously with the fixation or separately from it, it can be controlled in that one controlled length reduction or one controlled Voltage, which can be zero, is applied, and it can, just like the fix! Include some measure.

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It will be appreciated that when practicing the present invention the choice of temperatures, contractions and relaxations depends on many factors as well as the properties. the betrayed threads, the nature of the device used, " and the particular combination of properties desired in the heat treated filaments. The invention is illustrated by the following examples «The Examples are not to be understood in a restrictive sense »

Example I.

Melt-spun filaments of polyethylene terephthalate with a viscosity number of 0.62 and a birefringence of β χ 10 "were drawn in steam at atmospheric pressure to a linear density of 4 denier. They then had the average properties given in line 1 of Table I. . After a relaxation! at a voltage of zero and at 200 ° C, thereby '/ on subsequent shrinkage zero to achieve at 200 ⁰ C, were the new properties as Video- indicated in line 2 of table I. However, if this drawn thread was heat-treated according to the invention in two stages, the first stage in a fixation at constant length and at 200 ⁰ C and the second stage in a relaxation at a tension of zero and at 200 ⁰ C, then the resulting the strands of the improved Eigenschafttn are in Zeil "3 indicated by table I. the Vorechruupfung was old less reduction in modulus and tensile strength durchgefüh rt,

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Ί ·

Table I.

Temp, d «. after
Stretch pre
absorbed heat
treatment 2 = relaxa
tion at
. one
tension
v, zero r-
Thread properties at
20O ⁰ C Tear featlg
kelt in
g / den at
200 ⁰ C Hot
strain at
200 ⁰ O shrinkage
at 200 ^° C
in % 1. Fixie
tion at
constant
length 200 ⁰ C tension
In g each
the at
looser
strain 1.5
0.2 ' at
25 ° C 2.5
2 at 25th
50 22nd
0 1.
2. 200 at
25 ° C 0.75 5.0
4.8 2.8 11th
40 50 0 E.g, 200 200 4.8
1.2 1.8 5.2 2.8 24 25th . 0 E.g.
II 250 2.0 5.% 16 2.9

Example II

The verstreakten threads of Example Σ were wttrraefixiert at a constant Längfc und'bei 250 ⁰ G, is followed by a relaxation offered zero voltage and Castle t at 200 ⁰ C to · = Treated on DIECA catfish finished filaments had the "parent improved properties which are shown on line 4 of Table I - The higher modulus yarns, measured at tension below 10% elongation, were found to have improved elastic backbone properties.

Three samples of the drawn filaments of Example 1 were gemiiß the invention warraebehandelt _f by at a constant LI? ige i'nd at different temperatures, namely 200 ° C, 21'λ ° (; and fe? 0 ° Q, heat fixed umt then at

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a tension of zero and at 200 ⁰ C were relaxed. The resulting threads had a shrinkage of all zero at 2Q0 ° C, but the increase of the titer between the stretched and heat-treated filaments were only 12.2 #, 4 # 8 * or c t 4.7% compared to 22% in a one-step , post-stretching relaxation process. If, therefore, it is desired, at a given spinning speed and a given draw ratio, a thread with a certain denier without a free relaxation

ο *

200 G, then the introduction of a fixation stage at constant length and at 230 ° C increases the spinning productivity per spinning hole by about 16 %.

Example IV

"/ Stretched threads of polyethylene terephthalate with a viscosity number · of 0.62 and a shrinkage of 8 % _t which needed a tension of 5 * 5 g / den to stretch them by 5 $, were subjected to a two-stage treatment according to the invention, As shown in Table II, "For the purpose of comparison, the results of this treatment were compared to two comparative tests. The first was a one-stage heat treatment that included relaxation only / and the second was a two-stage heat treatment _for one more than 3 # reduction in length was allowed in the first stage »

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»" 9 ^a -

Table XI

vT ar roeb snanc ^ XUhg 4 £ empera =
door in
⁰ C Relaxation tension
in
g / den FadeneXgenenscharten shrinkage
at 100 ^° C
in % Stretching "
te threads Fixation - Tempera- =
tur ₀ in
C. -Tension
up to 5 %
strain
in g / deii 8th example
IV Contract I <
on in % 180 ° 0 5.5 0 comparison
1
comparison
2 180 100 0
0 3.5 0.
0 2 100
100 2.3
. 1.8 6th

These results show that the heat treatment of Example IV nauh a relaxation for removing a shrinkage at 100 ⁰ G a higher modulus resulted _s than simply a = stage © Relaxafcionsverfahren and that "above sea level to reduce the length in the first stage β% Isar “The module _{e was} not increased as in the case of the single-stage relaxation but was further reduced by ^{3 ο}

Example V

A 500 to ~ 0ara consisting of 24 Polyäthylenterephthalatfäden with a Viskositätssahl of 0.69 / was passed over a Vorspannungsvolle around a feed roll, which was erhitst to 100 ⁰ C * with a sufficient arc of contact, to ensure a satisfactory heat transfer and a negligible slip. " From the feed roll, the yarn was long stn 15.2 on the surface of a, erhitsten on 2Io ° C PXWr guided around 2, and then identical to two, heated to 220 ⁰ C ,, Veratreekrollen The applied draw ratio was 4j, 8 and the drawing speed 438.9 m / min. The pair of stretching rollers were close together in a ver °

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ι closed box angeordnetj weΙαhem in air with a \ temperature of 200 ⁰ C was circulated. The yarn was looped around this pair of pods eight times to ensure satisfactory heat transfer and minimal slippage 'and then passed out of the box and around another roller of the same diameter, but which ran J5% slower than the two heated rollers' . After sufficient bow contact around the end roll to ensure adequate cooling and minimal slippage, j the yarn was wound onto a bobbin _B

; Most of the stretching during the stretching process took place near the sheet contact with the feed roll, and the stretching was completed by stretching further over the platen. The Verstreckrollen met the following three funct ion s * applying the drawing tension to the previous Verstreckverfahren3 performing a \ heat fixation treatment at a constant length during: eight revolutions of the yarn around the same; and feeding the heated yarn to the subsequent relaxation process.

The physical properties of this yarn are given in Table III * where they match the properties of a complete the same drawn yarn are compared which had been wound on a bobbin without being subjected to the two-stage treatment according to the invention,

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properties

Table III

Example V yarn

Comparison thread * stretched but not heat treated

Titer (den) 107 105 Tensile strength (g / den) 8.24 8.08 Elongation at break {%) 10.6 10.5 Initial modulus (g / den) 129 136 Shrinkage in boiling 2.4 7 * 1 Shrinkage in air at
175 ° C 6.0 · 13.4. j Shrinking force in boiling
Water (g / den) 0.22 0.46 Shrinkage force in air at
175 ° C (g / den) 0.29 0 _Γ 62
i
1

In this example, the heat treatment was chosen so that the shrinkage and shrinkage force were reduced by more than a factor of 2, while the tear strength and elongation at break were increased slightly . This was achieved at the expense of only a 5 $ decrease in the particularly high initial modulus .

It is clear that those heat treated according to the invention! Threads either alone or in admixture with other synthetic or natural fibers in the case of a large number of Textile products can be used, such as sewing threads, Gorde, knitted fabrics and woven fabrics *

A particular example of such an improved product is example VI.

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• 12 · -
Example VI

A sewing thread was made from the heat-treated polyester thread of Example V made using cotton a conventional technique to make a core spun thread. As can be seen from Table IV, the suture had an improved combination of properties compared to a thread similar to that used in Example V for comparison non-heat-treated polyester yarn was made »

Tabel IV 422 Comparative *
sewing thread Properties Improved
Sewing thread 7.75 435 linear density den 7.78 11.02 Twisting in detail,
Turns / cm S 1.78 7.83 Twisting in the strand,
Turns / cm Z 4.21 ■ 1.48 Breaking load, kg 15.8 3.43 Tear strength, g / den 2.69 18.8 Elongation at tear, % 31.3 2.64 Loop maturity stiff, g / den 0.63 24.7 Initial modulus, g / den at
100 % elongation 1 * 96 0.62 Yield stress, %
(yield stress) 85.1 3.00 Flow deformation, %
(yield strain) 0.9 86.0 elastic regression
5 Ji elongation, % 2.6 1.0 Shrinkage in hot air of
US ⁰ Ci W 0.01 5.0 Shrinkage in hot air of 0.02 ο, οι Shrinkage force in hot air
of i% SrC * g / den 0.03 Schruspficraft in hot air

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Claims (1)

PATENT APPLICATION H E Multi-stage, post-stretching heat treatment process for aromatic polyester threads, characterized in that at least one intermediate heat treatment stage is switched on before a relaxation stage _e at which intermediate heat treatment stage the temperature is not lower than the previous stretching temperature and the subsequent relaxation temperature, the tension is higher than the tension of this Relaxation level, and the permitted reduction in thread length not greater than "3 % and not less than zero 1st. 2 ο method according to claim 1, characterized in that that the heat treatment is carried out in two stages. 3ο method according to claim 1, characterized in that that the relaxation stage is off = at a voltage of zero will lead ο 4ο method according to claim 2, characterized in that that the relaxation stage is off = at a voltage of zero will lead » 5. The method according to any one of claims 1 to 4, characterized characterized that the aromatic polyester is derived from terephthalic acid and ethylene glycol » 6. The method according to claim 5 j, characterized in that the heat treatment temperature is ^{at least 200 0 C,} '/ Ό Method according to claim 5 * characterized in that the heat treatment temperature is at least 230 ⁰ G, BAD ORiGfNAL 009809/1640 8. Two-stage, after stretching, heat treatment process for threads »which contain at least 95 Jf ethylene terephthalate units, characterized in that the temperature T in ⁰ C, the time t in min and the percentage permitted reduction in the thread length R in the first stage are such that the value of the expression: 1.47 - 0.009 T + 0.00Q035 £ ² + 0.35 logt + 0.066R - 0.009 R ² - 0.039s + S (O, Q12R - 0.066 logt - Q, OOO77T) is less than 50 % of its value when T, t and R are the values of time, temperature and the allowed decrease in thread length in the second stage in which at least there is a low voltage, the Terape "temperatures between 100 and 250 C are _5, the contraction and relaxation respectively are less than 8% and bE ~ treatment times of between about 0.001 and 0.05 min are" 9. Two-stage, after stretching heat treatment process for threads containing at least 95 % ethylene = terephthalate units, characterized in that the temperature T in ⁰ C, the time t in minutes and the percentage permitted reduction in the thread length R in the first stage such are that the value of the expression: 1.47-0.0OST + OOOOO35T ² + 0.35 logt + O, O66R - 0.009R ² - 0.039s * S (0.012R - 0.066 logt - O, OOO77T} less than 50 % of the value of the expression: 0.75 - 0.0025 dr where Tr is the temperature of the second stage in which the tension is essentially zero, these temperatures being between 100 and 250 ⁰ C, the prosentual contraction being less than 8 #, the fixation time between approximately 0.001 and 0, 05 min and the relaxation time is more than 0.05 min. ^λ ' 10. The method according to any one of claims 8 or 9, characterized. in the temperature in the first stage DAFL min ~ is least 200 ⁰ C. BATH ORIGINAL 009809/1640 11. The method of NaOH in any of claims 8 or 9, "characterized in that the temperature in the first stage is at least 230 ⁰ C. 12. The method according to any one of claims 1 to 11, characterized characterized that the fixation nod the relaxation in one continuous processes are integrated. MTENTANWXtTE .Η. FINCKE. 0IR.-INO. H. DtFL-ING. & STAEGK 009809/1640