DE704824C - Process for the production of artificial threads or films from cellulose acetate - Google Patents

Description

, Ind. Own dome

3 0 MEI 1941

ISSUED ON
APRIL 8, 1941

The invention relates to the manufacture of artificial threads and films from cellulose acetate.

In British Patent 352445 is S describes a process, threads from cellulose esters and ethers a natural one To give fibers similar structure, which can be recognized as such by X-ray analysis. In this way, in particular, a great improvement in the tensile strength is achieved.

The method is based on that threads of Celluloseestern -äthern or with a neutral organic swelling agent strongly swelled and taken up plastically and then stretched to at least 200 o / _o of its original length. The plasticity of the thread is such that it can easily be stretched up to 10000 / o and more. That in the mentioned

swelling agents listed as particularly suitable is a mixture of about 500/0 dioxane and about 500/0 water; it is applied at room temperature. In this process, the thread must remain in the dioxane-water mixture for several minutes.

When using a bath of acetone and water at room temperature it is so far impossible to produce with a finished, dry or wet spinning process. provided thread to achieve a stretching that of the stretching in the dioxane-water mixture equals.

If the aoeton concentration is too low, no stretching can be achieved at all. Will If the acetone concentration increases, then even with more than 40 percent by weight of acetone the State of swelling and plasticity cannot be achieved with dioxane-water mixtures obtained from the concentration according to the British patent.

The threads produced in this way do not have the properties of those in dioxane-water mixtures stretched threads.

It has now been found that the same results as the British Patent 352445 with baths of acetone and water without prolonged residence time of the threads in the baths can be obtained if you have a freshly spun, i.e. processed thread still swollen with acetone.

Although it has already been proposed in British patent specification 434425, cellulose acetate threads in acetone-water mixtures with at least 400/0 acetone at room temperature to stretch. However, this method can only be used to a limited extent take place; the thread obtained in this way shows only a moderate increase in strength the unstretched thread.

One can, however, by stretching in relatively dilute aqueous acetone

o solution threads obtained whose properties are those of the threads according to the British patent 352445 correspond if one works at a relatively high temperature and the threads are processed in the state how they emerge from the spinneret, so still swollen by acetone.

In particular, it has been found that wet spinning of a cellulose acetate solution in an aqueous acetone solution

o standing coagulating bath under the following conditions an artificial thread of high tensile strength can be obtained. Compared to the procedure under the British Patent 434425 is the ability to stretch many times greater; simultaneously the tensile strength is increased several times.

The temperature of the acetone-water mixture should be above room temperature and close to

ο or · are themselves above the boiling point of acetone. Good results are achieved when a bath temperature of about 50 to 65 ^{0 is used} . The acetone concentration should be 20 to 30 percent by weight. In such a way of working, it is not necessary to add other substances to the bath that delay the precipitation effect in order to achieve shiny threads. This is probably due to the fact that with

ο a stretch of over iooo <y _{0 is being} worked.

Furthermore, when carrying out the method according to the present invention, it is advantageous to stretch at high speed, ie the finished thread should be wound up at a speed of at least 100 m / min. The speed can even reach 250 to 300 m per minute. The 'acetone concentration at elevated speeds Aufwicklungsgeschwin- <o be reduced in the coagulation bath.

The present process can easily be used with cellulose acetate spinning solutions in one suitable solvents, preferably acetone, are carried out; the cellulose acetate concentration can be between 20 and 350/0.

The holes of the spinneret should have a diameter of more than ο.12 mm, preferably from 0.15 to 0.20 mm. To reduce the pressure of the spinning solution in the spinning device and to facilitate the diffusion of the acetone at the moment of For thread formation, it is advisable to run the spinning solution at an elevated temperature before spinning, preferably to be kept at the temperature of the coagulating bath. For simplification In the process, the coagulating bath itself can be used as a heating fluid for the spinning solution will.

The thread produced in accordance with the present invention has tensile strength of more than 3 g / den. It can also have a tensile strength of 4 g / den, and probably can be achieved even more. The elongation at break is about 6 to 70.Ό. To or during the manufacture of the thread it can be twisted, oiled or otherwise treated are to be used in various textile finishing processes to facilitate. It can also be subjected to saponification to give it an affinity for direct dyeing cotton dyes to rent. Furthermore, it can experience swelling with or without stretching to increase the elongation at break.

example 1

Contains dissolved in acetone, a spinning solution containing 27 0/0 cellulose acetate, is used in an aqueous coagulation bath at 23 to 25 weight percent acetone, that is maintained at 63 ^0, spun. The nozzle openings are 0.18 mm; the winding speed is 114 m per minute.

The obtained thread with 80 single threads has a titer of 60 denier and has a tensile strength of 3.5 to 3.8 g / den, with an elongation at break of 6 to 7.5%.

Example 2

A spinning solution containing 35% cellulose acetate dissolved in acetone is gespönnen into an aqueous coagulation bath with 28 to 29 percent by weight of acetone at a temperature of 50 ^0th The winding speed is 100 m per minute and the spinnerets have openings of 0.18 mm. The thread obtained gives a titer of 100 denier for 150 threads and has an elongation at break of 12c 3.1 g / den, and an outermost elongation of 6.20 / 0.

Claims (2)

Patent claims:
ι. Process for the production of threads or films from cellulose acetate, characterized in that the structures formed from a solution of cellulose acetate in acetone through nozzles, still swollen with acetone, are at least 35 °, expediently at 50 to 65 °, in a 20 to 30 percent by weight Acetone-containing aqueous precipitation bath stretched at a take-off speed of at least 100 m per minute. 2. The method according to claim 1, characterized in that the cellulose acetate solution is kept at the same temperature as the aqueous acetone bath. BERLIN. OEORfCKT! .N THE EMPIRE