US2811410A

US2811410A - Spinning of polyamides into a low humidity environment

Info

Publication number: US2811410A
Application number: US369717A
Authority: US
Inventors: Munch Werner; Maderno Cesano; Notarbartolo Luigi; Bruni Gaetano
Original assignee: Perfogit SpA
Current assignee: Perfogit SpA
Priority date: 1952-08-06
Filing date: 1953-07-22
Publication date: 1957-10-29
Anticipated expiration: 1974-10-29
Also published as: DE1036459B; GB738067A; FR1081615A; BE521879A

Description

United States Patent SPINNING OF POLYAMIDES INTO A LOW HUMIDITY ENVIRONMENT Werner Miinch, Cesano Maderno (Milan), and Luigi Notarbartolo and Gaetauo Bruni, Milan, Italy, assignors to Perfogit Societa per Azioni, Milan, Italy No Drawing. Application July 22, 1953, Serial No. 369,717

Claims priority, application Italy August 6, 1952 6 Claims. (CI. 18-54) This invention relates to an improved spinning process applicable to the production of spun goods from synthetic linear polymers.

In spinning such polymers it is very diflicult to obtain well wound thread packages, such as bobbins, especially when operating at high speed, as it is common practice to operate. Actually it is observed that if no special precautions are taken the thread bobbins are not regularly wound or at any rate the winding swells out in such a way that it becomes difficult later to unwind the thread and that in so doing numerous breakages occur. These phenomena are attributedto the absorption of moisture on the part of the thread. It has been suggested to avoid the trouble by extruding the polymer in an atmosphere of steam. However the use of steam is a complication and has drawbacks of its own.

According to the invention, the purpose of avoiding the aforementioned troubles is achieved in a very simple and advantageous manner and perfectly wound yarn packages are obtained, by extruding the polymer in the customary way, by winding up the resulting thread at a suitable temperature in an atmosphere with a low relative humidity, preferably less than 50%, and by leaving the wound thread in such atmosphere during some hours. After such treatment, not only is it possible to unwind the thread without ditliculty, but it is found-and this is unexpected and surprising-that it may be unwound equally well even if it is left before unwinding for hours or even days in an atmosphere with such a relative humidity as would have caused a bad winding of the yarn if the same had been formed by direct extrusion in said atmosphere.

The advantages of the invention will be made clear by the following comparative example which has a character of illustration implying no limitation and which refers to one particular polymer, and precisely to a polyamide obtained by polymerization of aminocaproic acid or of caprolactam. If such a polyamide is spun from the melt at a speed, for instance, of 1000 meters per minute, forming a 15 denier yarn in an atmosphere at the temperature of 2023 C. and at the relative humidity of 65-70%, the windings finally obtained uponbobbins are considerably swollen, so much that the yarn is practically detached from its support. If it is attempted to unwind these bobbins at a speed, for instance, of 200 meters per minute, they unwind badly with a considerable number of yarn breaks.

If the same polyamide is spun at the same speed and with the same count and is wound on bobbins in an en- "Ice vironment at the same temperature but at a relative humidity of 45%, the resulting bobbins are excellent and quite compact. If these bobbins are left in said low humidity atmosphere for a period of time which may go from 2 to 36 hours, but which is preferably comprised between 18 and 26 hours, and are later brought into an environment having the same temperature and a relative humidity of -70% and are left there for some hours or even for .one or two days or even more, they can be unwound in this latter environment at speeds even higher than 200 meters per minute without any difliculty and without any breakages occurring. The bobbins, after they have been wound and conditioned in the low humidity environment, swell but very little if brought into a normal or relatively high humidity environment, and even after they have remained therein a sufiiciently long time, contrary to what was to be foreseen.

What we claim is:

l. A process for the spinning of synthetic linear polyamides, comprising the steps of forming polyamide filaments by extruding a molten polyamide through a spinneret into an environment, maintaining in said environment a relative humidity not higher than 50%, winding the extruded filaments onto packages in the said environment, and conditioning said filament packages by keeping them in an environment having a relative humidity not substantially higher than 50% for a period of time comprised of between 2 and 36 hours.

2. A process according to claim 1, wherein the filament packages are conditioned by keeping them in an environment having a relative humidity not higher than 50% for a period of time comprised between 18 and 36 hours.

3. A process according to claim 1, comprising the additional step of transferring the filament packages into an environment having a relative humidity substantially higher than 50% and subsequently unwinding said packages therein.

4. A process according to claim 1, wherein the filaments are Wound onto packages at a liner speed not substantially lower than 1000 meters per minute.

5. A process according to claim 1, wherein the environments having a relative humidity not substantially higher than 50% have a temperature not substantially lower than 20 C.

6. A process according to claim 1, wherein the polyamide, is that obtained by polymerization of caprolactam.

References Cited in the file of this patent UNITED STATES PATENTS 2,157,117 Miles May 9, 1939 OTHER REFERENCES Nylon Technology (Indefurth), published by Me- Graw-Hill (New York); pages 51, 196, 228 relied on. (Copy in Scientific Library.)

Customer Service, Nylon, published by E. I. Du Pont; pp. 3-701 and 3-8.01 relied on. (Copy in Scientific Library and in Div. 43.)

The Textile Manufacturer (British), April, 1939; p. 143 relied on. (Copy in Scientific Library and in 281N.) 7Ser; No. 307,983, Schlack (A. P. 0.), published April 2 1 34.

Claims

1. A PROCESS FOR SPINNING OF SYNTHETIC LINEAR POLYAMIDES, COMPRISING THE STEPS OF FORMING POLYAMIDE FILAMENTS BY EXTRUDING A MOLTEN POLYAMIDE THROUGH A SPINNERET INTO AN ENVIRONMENT, MAINTAINING IN SAID ENVIRONMENT A RELATIVE HUMIDITY NOT HIGHER THAN 50%, WINDING THE EXTRUDED FILAMENTS ONTO PACKAGES IN THE SAID ENVIRONMENT, AND CONDITIONING SAID FILAMENT PACKAGES BY KEEPING THEM IN AN ENVIRONMENT HAVING A RELATIVE HUMIDITY NOT SUBSTANTIALLY HIGHER THAN 50% FOR A PERIOD OF TIME COMPRISED OF BETWEEN 2 AND 36 HOURS.