DE2239312A1 - METHOD FOR MANUFACTURING MOLECULAR ORIENTED AND SHRINKLOW POLYESTER FIBERS - Google Patents

Description

Our reference: O.Z. O588 / OIO2O Gr / Wil 6750 Kaiserslautern, June 8, 1972

Process for the production of molecularly oriented and shrinkage

poor polyester fibers

The invention relates to a method for the production of molecularly oriented and low-shrinkage polyester fibers in one operation and the polyester fibers produced by this process.

The production of polyester fibers is known to take place in three procedural steps. During spinning, threads are formed from the polymer melt, which are then cooled and drawn under the spinneret and either wound up or deposited in suitable cans. The working conditions in this process step are chosen so that the threads referred to as "undrawn" are characterized by low molecular orientation. In the subsequent stretching process, the "undrawn" Fibers mechanically drawn, with a high molecular orientation being achieved at the same time. This stretching will basically carried out at a temperature which is higher than the transition temperature of the second order. It is also known carry out the stretching in two or more stages. · In a subsequent fusing process, the Stretching and frozen tensions of the chain molecules eliminated by thermal treatment. Included the degree of crystallization is also increased. The fixation can take place in the de-energized state or under the tension of the Threads are carried out.

As a rule, these three procedural steps become perfect carried out separately. In some cases, stretching and fixing are carried out in one operation. With modern procedures even all three process steps are combined in one operation. In all known processes, even if two or three of the process steps mentioned are combined, acts it is just a simple stringing together of the individual steps,

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but not a functional connection. After this polyester fibers are almost exclusively produced today in traditional processes.

A further development in which two process steps are combined into a qualitatively improved process is the "draw spinning process". The polyester fibers are drawn and drawn under the nozzle, giving the threads a higher molecular orientation. In US Pat. No. 2,604,689, take-off speeds of 2,745 m / min to 4,755 m / min are mentioned. These high-shrink fibers should have a high molecular orientation, the boiling shrinkage has values between 3 and 30 %. US Pat. No. 2,604,667 describes that the boiling shrinkage can be further reduced by increasing the take-off speed above 4,755 m / min. This also increases the molecular orientation. However, there are practical limits to the increase in the take-off speed due to the occurrence of capillary breaks under the spinneret. According to HH Hebeler, this limit is 41,000 "denyards". "Denyard" is defined as the product of the linear density in deniers and the take-off speed in yards per minute. In Belgian patent 552 129 it is recommended not to exceed the take-off speed of 2,743 m / min when drawing the threads in a bath of inert liquid at a temperature above the transition point of the second order the production of oriented melt-spun synthetic fibers in a single operation of the take-off at speeds between 1,600 m / min and 2,600 m / min is prescribed. The temperature of the gas medium immediately below the spinneret should be 10 ° to 80 ° C lower than the melt temperature of the polymer.

All of the above-mentioned methods relate to the regulation of the take-off speed and the cooling conditions under the Spinneret. None of the patents mentioned take the influence into account the melt rheology, d. H. the processes in the spinneret and just below the spinneret. These known draw spinning processes have not been able to introduce themselves to any significant extent for the industrial production of polyester fibers,

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It has been found that to achieve a high molecular weight

Degree of orientation besides the take-off speed also the

Melt extrusion rate is critical is.

The extrusion speed is the mean speed, with the melt fiber-forming polymer through the capillary the spinneret is extruded. As an effective take-off speed one denotes the speed with which the spun Fibers pass through the exhaust system. The quotient of the effective take-off speed and the extrusion speed becomes referred to as the stretching ratio -

It has now been found that for the production of polyester threads oriented from the spinneret by this process the extrusion speed should be greater than 20 m / min if possible.

It has also been found that in the production of molecularly oriented and low-shrinkage polyester fibers by extruding the polymer melt of a fiber-forming polyester through holes in a spinneret to form threads, a considerable improvement and functional merging of the operations are achieved; h "The threads are cooled, pulled off, stretched and oriented in one operation if the injection speed at which the polymer melt is pressed through the bores of the spinneret is more than -J> 0 m / min, preferably more than 40 m / min and the withdrawal speed to 50 to 100 times, preferably 65 to 200 times the injection speed.

The diameter of the nozzle bores can be between 0.15 ram 0.80 mm can be varied, although it is advantageous to work with the smallest possible nozzle bore diameter. Appropriately Nozzle bore diameter knives smaller than 0.15 mm should not be used. It is also useful Use spinnerets in which the length of the capillary of the nozzle bore is at most five times the length of the diameter is limited. Under the above conditions, the

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The polymer melt already forms a molecular one in the capillary of the spinneret Pre-orientation given, which facilitates the subsequent orientation between the spinneret and the take-off element.

Furthermore, the temperature control between the spinneret and the deduction device is of great importance. The spun fibers can pass through cross-flowing gas media under the spinneret be cooled down. However, it is also possible to carry out this cooling in a water-cooled chute or else to forego cooling. The type and intensity of the cooling affects only the achievable with aerodynamic deduction Oriented fiber titer.

However, the setting of the draw ratio or the take-off speed is essential for the process according to the invention. Does the extrusion speed meet the above mentioned conditions, the draw ratio should be set to 50 to 3OO in order to produce fibers with a high molecular weight To get orientation. However, stretching ratios are advantageous between 65 and 200 applied. As a result, the effective take-off speed is 50 to 300 times, but preferably to 65 times to 20O times the respective Extrusion speed set. The effective take-off speed does not necessarily have to be the maximum speed be used to transport the spun fibers. The thread experiences a positive acceleration directly under the spinneret, which passes through a maximum and then drops again to the value zero.

Immediately after the stretching process, there is a relaxation area in which existing internal stresses in the molecular fine structure can be eliminated. In this relaxation area, the acceleration of the fibers can be negative Accept values.

The heat setting can be achieved by secondary heating of the fibers be improved. It is particularly advantageous if this is done through the take-off devices. The exhaust system can be mechanical or aerodynamically operating devices can be used.

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Mechanically working organs can be, for example, rotating rollers (godets), roller groups, and reel pairs and / or circumferential bands as well as combinations of these organs.

Injectors with a round or flat shape can serve as aerodynamic discharge organs. The mechanical trigger mechanisms allow the transfer of greater forces to the spun fibers, this allows a more precise setting of the desired technological parameters of the spinning process facilitated. On the other hand, occur when using mechanical Elements have serious technical problems at higher speeds. In contrast, the aerodynamic exhaust organs are in the speed is less limited. However, they are too forces transmitted to the thread by flowing gas media. The energetic efficiency decreases with the power to be transmitted. A precise setting of the technological spinning and drawing parameters is aerodynamic Difficult to withdraw.

For further use, the stretched and heat-set Fibers are wound up or placed in suitable containers. However, it is also possible to place the fibers immediately below to put down the take-off device to form a flat textile structure. The take-off devices can be used to wind up or deposit. Furthermore, a winding or depositing device can be connected downstream of the take-off device. Finally, combinations can also be used be used by mechanically and aerodynamically working organs.

The polyester fibers produced according to the invention are distinguished by a high molecular orientation. So were, depending on the Single fiber titre, birefringence values from Ο, ΐβΟΟ to 0.2100 measured. The values of the azimuthal half-widths were between 15 ° and 25 °. These values are also included conventionally spun and drawn polyester fibers. From the force-strain diagrams it can be seen that the after fibers produced by this process, as well as conventionally

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spun polyester fibers, plastic range. the very low shrinkage values obtained by this process The fibers produced are further proof that these are fibers with a highly oriented and relaxed molecular weight Fine structure acts.

example 1

The spinning device consisted of a spinning extruder with a screw diameter of 45 mm, which was operated by means of a spinning pump supplied a spinneret with polymer melt. Under the spinneret there was a blow shaft that served to cool the deformed fibers. For spinning the spun fibers An injector operated with compressed air was used, which placed the fibers in a can with a perforated bottom.

For the spinning tests, the polyethylene terephthalate with a relative viscosity of 1.385, which was matted with 0.5% titanium dioxide, was used. The viscosity was determined in a 0.5 # strength solution of a mixture of phenol (3 parts by weight) and o-dichlorobenzene (2 parts by weight). The spinneret had 32 bores with a capillary diameter of 0.8 mm and a capillary length of 2.0 mm. The flow rate of the polymer melt was 416 g / min. This resulted in an extrusion speed of 21.5 m / min. The spinning temperature was 285 ⁰ C. The air velocity in the Abzugsinjektor was adjusted so that the fibers were taken off at a speed of 4170 m / min. The resulting draw ratio was 194.

The spun fibers were characterized by the following physical and mechanical properties:

Single fiber titer (dtex) 24.8 tenacity (p / dtex) 2.86

Elongation {%) 112 Shrinkage {%) 2 Density (g / cm ⁵ ) 1.3505

Birefringence 0.1624

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When looking at the force-strain diagrams, there were none Flow zone more present {natural drawing ratio) "

In a comparative experiment, only the delivery rate was increased 192 g / min changed so that the extrusion speed only reached 9.9 m / min. Furthermore, in this comparative experiment, the air speed in the vent injector was set so that that the fibers were drawn off at a speed of 5,640 m / min. This resulted in a drawing ratio of 570.

Fibers are obtained with the following physical and mechanical properties %

Single fiber denier (dtex) 16.1

Strength (p / dtex) 2.37

Elongation {%) - ■ 226

Koeh shrinkage {%) 36

Density (g / cm ⁵ ) JL, 3490

Birefringence 0.078

The force-strain diagram shows a very clear flow range. This suggests that the fibers are not fully drawn, _etc.

Example 2

The spinning equipment was the same as described in Example 1. A spinneret with 64 bores and capillary diameters of 0.6 mm with capillary lengths of 1.5 was used. The delivery rate of the polymer melt was "set at 512 g / min, and the extrusion rate was 2J> ₃ 6 m / min, the air velocity in the Abzugsinjektor was adjusted so that the fibers were drawn at a rate of 6 880 m / min Draw ratio.. in the process 292. The propellant air had a temperature of 120 ^° C., so that the fibers were partially fixed at the same time during this process.

Fibers spun in this way were characterized by the following physical properties and mechanical properties

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- β - 14.2 O.Z. 0588/01020 3.15 2239312 Single fiber titer (dtex) 91 Strength (p / dtex) <1 Elongation (%) l, 3736- Cooking shrinkage (%) 0.192 Density (g / cm ^) Birefringence

The force-strain diagram shows no flow area.

Example 3

The spinning device consisted of a spinning extruder with a screw diameter of 45 mm, which was operated by means of a spinning pump supplied a spinneret with polymer melt. Under the spinneret there was a water-cooled chute, which was used to cool the deformed fibers For the spun fibers, a compressed air injector was used. The spun polyethylene terephthalate corresponds that of Example 1. The spinneret used had 64 holes with a capillary diameter of 0.4 mm and one Capillary length of 1.0 mm. The flow rate was increased to 230 g / min set. The extrusion speed corresponded to 21.2 m / min. The air velocity in the vent injector became like this adjusted so that the fiber take-off speed was 4,880 m / min. The draw ratio was 230.

The fibers spun in this way were characterized by the following quality features;

Single fiber titer (dtex) 7.02 strength (p / dtex) 3.05

Elongation (%) 118 Shrinkage (%) 4.2 Density (g / cm3) 1.3535

Birefringence 0.168

The force-strain diagram shows a slight hint of a flow area.

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For comparison, fibers were spun with the same spinning device at a delivery rate of 180 g / min. The extrusion speed was 16.6 m / min, with the same setting of the draw-off injector, fiber take-off speeds of 3,920 m / min and a draw ratio of 236 set. From the force-strain diagram on this Wise spun fibers showed a pronounced flow area visible, which suggests incomplete stretching.

The pasers were characterized by the following physical and mechanical properties

Single fiber titer (dtex) 6.90 Strength (p / dtex) 3.01 Elongation {%) 135 Cooking shrinkage (%) 22nd Density (g / cm5) 1.3502 Double refraction 0.078 Example 4

It was worked with _o der.im Example 3 described spinning device case, only a spinneret having 64 holes and a capillary diameter of 0.3 mm and capillary length of 0.75 was used ram. The polymer used in this experiment corresponds to the starting material, which was used in Example 1. "The spinning temperature was also 285 ⁰ C.

The spinning conditions in this example were as follows Way changed §

A
position Support
lot
(g / min) Extrusion
swiftly
speed (m / min) Deduction
dizzy
speed (m / min) Stretching
relationship 4.1 181 28.3 4610 I63 4.2 227 35.4 6 640 188 4.3 288 45.0 4,550 101 4.4 378 59.0 4 950 76 4.5 452 70.7 4 750 66

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The tapes made at these settings were good oriented and were characterized by good physical and mechanical properties.

The values are summarized in Table 1.

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Tabel

Spin settings of example 4

A
stel
lung Spinning conditions
^G o ^v o ^V P
(g / min) (m / min) (m / min) D. Fiber properties
Td -ff S
(dtex) (p / dtex) {%) e 3, 05 112 KS
(*) (g / cm ⁵ ) ^U D 163 4.1 1.81 28.3 ^ 610 I63 5, KS 3, 07 98 4th 1, O, 179 4.2 227 35.4 6 640 188 6 _p 3, 04 98 2 1, 0, 172 4.3 288 45.0 4,550 101 8th, 3, 12 92 3 1, 0, 183 4.4 378 59.0 4 950 76 11 3, 4o 83 • <1 1, ■ 0, 189 4.5 · 452 70.7 4 750 66 12, "^ i I ₃ O, CD
to
OO
O ^G o = Delivery rate (g / min) ' = Strength (p / dtex) CO ^v o = Extrusion speed (m / min) = Elongation {%) —A
* ^ »% ^V P = Fiber take-off speed (m / min) Boil shrinkage (
- * CJ
to = Stretching ratio Density (g / cnr) , 6 , 3545 .9 : ^) , 3555 , 4 I. , 3555 .3 , 3605 , 6 , 3608

Td

= Single fiber titer (dtex)

= Birefringence

Γ0

K) K) GO CO Ca)

K)

00 CO

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As can be seen from this table, the physical and mechanical properties are in the examined range of The spinning parameters largely depend on the take-off speed and also on the draw ratio, apart from the individual fiber titer independent. The single fiber titer increases significantly with increasing extrusion speed.

Example 5

Example 3 was followed in this experiment. The trigger injector however, it was replaced by a pair of heated godets and a mechanical winder / die allowed a maximum speed of 4,000 m / min. The spinneret was through one with 64 holes and capillary diameters of 0.2 mm and capillary lengths of 0.5 mm Replaced nozzle. The delivery rate was set to 140 g / min, so that an extrusion speed of 58 m / min. The take-off speed was set at 3,450 m / min set. The stretching ratio was 60.5 * The godets were heated to 120 ° C.

The fibers thus produced had the following physical properties and mechanical properties?

Single fiber titer (dtex) 5.94 Strength (p / dtex) 3.42 Elongation (%) 86 Cooking shrinkage {%) <1 Density (g / cm ⁵ ) 1.3595 Double refraction 0,201 Example 6

Example 5 was followed in this example. It was drawn over heated take-off godets and then drawn off with a take-off injector and placed in a perforated can. The flow rate was set at J6 g / min; the extrusion speed was 32 m / min. The withdrawal speed of the heated to 120 ⁰ C was takeoff godets

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set to 4 670 m / min. The sewn-on trigger injector was adjusted so that the pasers are under slight tension forwarded and placed in a perforated jug »

The on this. Wise spun fibers were also well drawn and had the following properties

Single fiber titer (dtex) 2.52 Strength (p / dtex) 3 ^ 64 Elongation (%) 72

Cooking shrinkage (%) <1 density (g / cm ^{3) 1.3735}

Birefringence 0.208

Example 7

The procedure was as in Example 4 with the difference that the spun fibers were placed on an endless screen belt to form a random fiber fleece. The fleece thus formed was then solidified with an acrylate binder and used as a coating material for PVC art Ie der ,,

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Claims (3)

Claims 1. A process for the production of molecularly oriented and low-shrinkage polyester fibers by extruding the polymer melt of a fiber-forming polyester through bores of a spinneret to form threads, these being cooled, drawn off, stretched and oriented in one operation, characterized in that the injection speed with which the Polymer melt is pressed through the bores of the spinneret, more than 50 m / min, preferably more than 40 m / min, and the withdrawal speed is 50 to 100 times, preferably 65 to 20O times, the injection speed, 2. The method according to claim 1, characterized in that the heat setting of the spunbonded material takes place simultaneously with the drawing, but at the latest at the take-off element, preferably by heating the take-off element and / or the flowing media surrounding the threads. 3. shrink arms polyester fibers, filaments and -Flächengebilde that this method are prepared according to claims 1 and 2. FIG. Lutravil Spinnvlies GmbH & Co. 409809/1034