DE1660294A1 - Process for improving the mechanical properties of highly elastic, segmented polyurethane threads - Google Patents

Description

FARBENFABRIKENBAYERAG 1660294

Dr BxploJ

September 1965 Reu / Hf

Process for improving the mechanical properties of highly elastic, segmented polyurethane threads

The invention relates to a method for improving the mechanical properties of highly elastic segmented Polyurethane threads through continuous thermal treatment of the threads at relatively high temperatures.

It is known that segmented polyurethane threads which have been produced by the TaS or dry spinning process may require a thermal aftertreatment so that they have certain physical properties.

Often, freshly spun elastomeric filaments of the spandex type are post-treated in hot water. On the other hand cheaper methods are known in which elastomeric filaments minutes and treated for up to 10 hours in hot air at temperatures between 100 ° and 150 ⁰ C in the discontinuous threads winding while keeping constant its length at least. 5 The purpose of such processes is to obtain a thread material that has the desired combination of elasticity, modulus, elongation at break and breaking strength. In general, jine

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high tensile strength with the highest possible elongation at break and optimal, elastic recovery capacity sought.

In the production of highly elastic elastomer threads, it has been shown that the known, discontinuous heat treatment of the thread material, especially on bobbins with a higher winding weight, very easily leads to different thread properties over the total thread length * The latter especially because the different thread layers take on the required temperature after very different times . ^{This means that the relation "treatment temperature / treatment time 11} " which applies to a certain constant thread tension is undefined. The outer thread layers, which are first brought to a higher temperature, assume correspondingly higher thread tensions, especially with material that is still shrinkable. This gives them a different thread characteristic than the inner thread layers Under certain conditions, even greater titre differences occur, which call into question a material that is flawless for processing.Another disadvantage of the initially increased thread tension of the outer thread layers is that strong pressure is exerted on the inner thread lengths of the lap the threads interlock strongly at their crossing points; that is, the round overall cross-section of the self-glued multifile is lost, which can lead to complaints when processing the material the

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ORIGINAL INSPECTED

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strong cohesive forces of the elastomer substance in strong Dimensions for bonding, so that especially with fine titers not only the overhead take-off, but also the rolling take-off of such laps is not flawless, namely not without noticeable and different stretching of the threads is.

A method has now been found for improving the mechanical properties of highly elastic, segmented polyurethane threads, in which the thermal aftertreatment of the segmented polyurethane threads can be carried out continuously and uniformly and in much shorter times than in known methods if the temperature is at least 180 ° and 10 ⁰ C below the glue point of the polyurethane thread works. The process of thermoplastic potting, which is accompanied by the reversible loosening of the hydrogen bonds in the hard segments, is triggered almost spontaneously at these temperatures, which are only slightly below the so-called sticking point and the substrate's own melting point. As a result, in contrast to known processes, there is the possibility of short-term and continuous thread treatment. Depending on the titer, type of preparation agent and selected temperature, dwell times of the thread in the heating zone between 2 seconds and approx. 2 minutes are required.

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The elastomer threads produced by the dry spinning process are in a metastable state when In particular, high spinning temperatures and high take-off speeds are used and therefore relatively high Thread tensions result during winding - If you treat this thread material in a relaxed state in hot water, so a shrinkage occurs. This property can be important in the manufacture of certain stretch goods or high bulk textile articles, but it is generally important undesirable. The latter all the more so as such a shrinking process results in a relatively strong change in the thread characteristics has the consequence. The force-elongation diagram may become too flat, and it is important for certain articles Retraction force is reduced. On the other hand, the combination of the individual physical properties of the metastable thread material has not yet been optimized, what is achieved by a suitable, thermal aftertreatment. The latter should preferably take place at temperatures which are above the temperature range that occurs during the processing of elastomer threads into textile structures as well whose equipment and coloring is chosen. The thermal post-treatment can be carried out with the help of heating godets, heating plates, . Performed in a heating channel or in any other suitable manner will.

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In the method according to the invention, the metastable

• Elastomer thread, for example, withdrawn from the spinning bobbin, then passes one or more, preferably three heating godets and is immediately wound up at the lowest possible thread tensions. The heating godets can be regulated separately both in terms of their circumferential speed and their surface temperature. Each heating godet is wrapped around the thread several times, preferably 10 to 25 times. The contact length of the thread on the gialette surface is about 20 to 60 cm per loop, depending on the diameter of the godet. The contact time can be varied depending on the titer through the thread speed and / or the number of wraps. In order to give the threads the optimal properties depending on the requirements, the procedure can be varied as follows by means of the heating godets which can be regulated separately with regard to their circumferential speed. In the simplest case, the thread passes the heating godets and is wound up immediately afterwards, the length specified on the transmitter bobbin being kept constant in every phase of the winding process. Depending on the requirements, the thread can be relaxed between the last heating godet and the winding device, which is equivalent to a jump of between 1 and 10 $ . In addition, the thread can be allowed to jump in, if necessary in stages between the individual godets, which results in an overall jump

009821/1714 _BA0 original

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5 of 5 is equivalent to 50 $ »preferably to 25 i ~. Particularly when treating threads with coarser titers, the procedure can be varied in such a way that the thread is warped between the transmitter bobbin and the first godet and / or the first and second godet, equivalent to a total draft of 1.1 to 2.0 times its " Immediately afterwards, the thread is relaxed ™ between the second and third godet and / or between the last godet and the winder, equivalent to a total thread jump of 5 to 50 # an additional preparation agent is suitably applied to the thread, as a result of which the thread is cooled more rapidly to temperatures below 60 ^° C. and, in particular, good running properties during subsequent processing are brought about.

For the post-treatment according to the invention of elastomer threads in a continuous manner at temperatures which are only slightly below the so-called glue point of the threads, the surface quality of the heating godets is significant Meaning. The running surface can be highly polished; however, semi-gloss surfaces are preferred used to avoid adhesion of the thread as much as possible, even under more extreme conditions, lethal iat

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the degree of adhesion of the thread material to heating godets depending on the effective godet temperature as well as the residual solvent content of the thread and the type and amount of spin finish used. The effective temperature of the godets is generally 5 to 40 C, preferably from 1'5 to 35 ⁰ C below the so-called adhesive point of the filaments material used. The glue point or Λ glue temperature of an elastomer thread is the minimum temperature at which a thread sample leaves a melted trace when it is pressed for five seconds under a weight of 200 g on a suitably preheated metal surface (e.g. Kofler bench). The glue point of the examples, the post-treated in accordance with threads located at 220 ⁰ C. This thread material has a residual solvent content (dimethylformamide) of max. 5 # »preferably less than 1 i" · The content of eingesponnenem matting agents (titanium dioxide) is between 1 and 5 $

To characterize the threads, inter alia. the following thread properties are determined.

1 «titer ■ 4. Elongation at break

2. Module 5. Breaking strength

3. Permanent elongation

SAD ORiQIMAL

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determined with a preload of 0.5 mg / den. The module specifies the force in g / denier output titer that is required to stretch the thread by 300 pounds of its span length; namely Verformungsgeechwindigkeit located min at 400 #. The so-called permanent strain or Reetdehnung is the percent elongation of the thread, which is determined after three expansion of the specimen at 300 $> and after a recovery period of 30 seconds. Elongation at break and breaking strength are determined in the usual way, the rate of deformation is 400 l> min. '"

The figure shows a special arrangement "for carrying out the process, the Fadenlsuf from the donor bobbin (spinning bobbin) 2 via the lower = friction roller 1, the heating godets 3, 4 and and the traversing thread guide 6 to the upper friction roller 7 and then to the take-up reel 8. The heating godet 5 has about 10 to 20 turns of the thread.

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BATH

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B e i s. P. i -e 11;

6000 parts of an adipic acid-hexanediol-1,6 / 2,2-dimethylpropanediol-1,3-polyester (molar ratio of the board 65: 35) with an OH number of 61.4 are ^{mixed with 1354 parts of 4 »4 f} -diphenylmethane diisocyanate and 1864 parts of chlorobenzene is heated for 1 hour at 100 ⁰ C and cooling the formed HCO-Voradduktlösung to room temperature.

8520 parts of the above NCO-Voradduktlösung be in a 70 ⁰ C hot solution of 182.5 parts of carbohydrazide in 17942 parts of dimethylformamide stirred in DMF titanium dioxide pigmented paste with 800 parts of a 33 # by weight and, after cooling to room temperature with 18 parts Hexandiisocyanat- 1.6 offset. The elastomer solution has a viscosity of 750 poise / 20 ⁰ C

Example 2:

800 parts of a polyester according to Example 1, but an OH number of 67 »1 258 parts of chlorobenzene is heated with 222 parts of 4,4 ^l -Piphenylmethan-diisocyanate and 80 minutes at 95 to 98 ⁰ C and then the resulting NCO-on Voradduktlösung Cooled to room temperature.

19.65 parts of ethylenediamine and 2.68 parts of 1-4 propylenediamine are dissolved in 2376 parts of dimethylformamide and approx.

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30 parts of solid COp added. 1100 parts of the above NCO pre-adduct solution are introduced into the suspension of amine carbonates formed. COP-developing a highly viscous elastomer solution containing a 33 # by weight of titanium dioxide-DMF paste has 20 ⁰ C after pigmentation with 90 parts of a viscosity of 520 poise /.

example

3:

A spinning solution prepared in accordance with Example 1 is briefly heated to 90 ⁰ C and immediately thereafter spun dry in a 48-hole spinneret at a cichachttemperatur of 200 ⁰ C. After leaving the spinning chute, a preparation agent to reduce adhesion is applied to the threads. The threads are wound up at a speed of 300 m / minute. The threads have a titer of approx. 400 den.

During the thermal aftertreatment, the threads pass three heating godets under the following conditions.

Ver
9UCh & -
No. Godet
temperature
( ⁰ C) Contact
Time
(Minutes) Approved
Entry
<*) 2
3
4th 180
200
200 0.57
0.48
0.11 /
10
/

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BATH

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The thermally aftertreated threads have the following changes in properties ^{compared to the starting material + '.}

Ver Titer module Stay strain Elongation at break also-
No. (the) (g / den) (#) ('/ ·) 1 ⁺ > 430 141 22.6 501 2 400 152 17.6 587 3 450 113 15.2 625 4th 420 161 16.6 540

example

4:

After passing through the first of three heating godets, the elastomer threads spun according to Example 3 are stretched by 100 ° and almost completely relaxed before being wound up.

Ver
search-
No. Godet
temperature
I ⁰ C) Contact-
Time
(Minutes) Approved
Entry
X ° / o) 2
3
4th 205 «
205
205 0.45
0.38
0.19 28
43
50

The thermally aftertreated threads have the following changes in properties ^{compared to the starting material + '.}

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Ver Titer module Elongation at break Breaking strength search- (the) (g / den) (g / den) 1 ⁺ > 430 141 501 0.83 2 310 300 504 0.86 3 390 155 588 0.81 4th 430 132 578 0.69

example

5:

A spinning solution produced according to Example 2 is briefly ^{heated to 65 °} C. and immediately thereafter dry-spun from a 12-hole spinneret at a shaft ^{temperature of 175 ° C.} The take-off speed is 450 m / minute. The threads have a titer of approx. 70 den.

During the thermal aftertreatment, the threads pass three heating godets under the following conditions.

Ver
search-
No. Godet
temperature
( ⁰ C) Contact
Time
(Minutes) Approved
Entry 2
3
4th
5 190
180
180
200 0.11
0.11
0.22
0.13 /
/
/
15th

The thermally post-treated filaments have over the off gange material * 'the following Eigenschafteänderungen on.

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BATH ORIGINAL

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Ver
search-
No. Titer
(the) module
(g / den) Elongation at break
(#) Breaking strength
(g / den) 1 ⁺ > 76 330 425 1.08 2 73 486 458 1.09 3 80 670 321 1.18 4th 69 270 541 0.92 5 79 178 607 0.90

Example 6:

A spinning solution produced according to Example 1 is briefly ^{heated to 70 °} C. and immediately thereafter dry-spun from a 12-hole spinneret at a shaft ^{temperature of 165 ° C.} The thread is partially relaxed before the first winding. The winding speed is 300 m / minute. The threads have a titer of approx. 70 den.

During the thermal aftertreatment, the threads pass two heating godets under the following conditions.

Ver ~
search-
No. Godet
temperature
( ⁰ C) Contact
Time
(Minutes) Approved
Entry
X ⁰ Io) 2
3 185
205 0.14
0.09 /
4.5

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The thermally aftertreated threads have the following changes in properties ^{compared to the starting material + '.}

Ver
search-
No. Titer
(the) module
(g / äen) Stay. Stretch
(*) Elongation at break Bru cbfes tigka. t
(g / denj) , ⁺ >
2
3 78
71
74 217
217
171 18.6
14.4
15.0 478
526
565 5.1
5.5
5.1

The breaking strength is related to the breaking titer.

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Claims (6)

166029A - w- Le A 9640 claims: 1. A method for improving the mechanical properties of highly elastic, segmented polyurethane threads by thermal aftertreatment, characterized in that the threads are ^{continuously thermally aftertreated in a temperature range of at least 180 ° and 10 0} C below the thread bonding temperature with residence times between 2 seconds and 2 minutes. 2. The method according to claim 1, characterized in that the thermal aftertreatment while keeping the constant specified thread length. 3. The method according to claim 1, characterized in that the thread is relaxed immediately after the thermal aftertreatment * 4. The method according to claim 1, characterized in that the thread is relaxed during the thermal aftertreatment - optionally in stages. 5. The method according to claim 1, characterized in that the thread is relaxed during the thermal aftertreatment and immediately after the thermal aftertreatment. 009828/1714 - 16 Le A 9640 6. The method according to claim 1, characterized in that one the thread during the thermal aftertreatment Subjected to default and relaxed again. 009828/171 A