US2480974A

US2480974A - Apparatus and method for producing high-tenacity yarns

Info

Publication number: US2480974A
Application number: US594787A
Authority: US
Inventors: George W Seymour; Dustin Y Miller
Original assignee: Celanese Corp
Current assignee: Celanese Corp
Priority date: 1945-05-19
Filing date: 1945-05-19
Publication date: 1949-09-06
Anticipated expiration: 1966-09-06
Also published as: GB612206A

Description

Sept. 6, 1949.

BY DUST INVENTORS.

GEORGE W. SEYMOUR.

IN Y. MILLER.

Patented Sept. 6, 1949 APPARATUS AND METHOD FOR PRODUCING HIGH-TENACITY YARNS George W. Seymour and Dustin Y. Miller, Cumberland, Md., assignors to Celanese Corporation of America, a corporation of Delaware Application May 19, 1945, Serial No. 594,787

4 Claims.

This invention relates to the treatment of yarns, and relates more particularly to the saponification of stretched yarns having a basis of an organic acid ester of cellulose whereby high tenacity regenerated cellulose yarns of superior physical characteristics may be obtained.

An object of this invention is to provide an improved process for the continuous saponification, in cake form, of high tenacity stretched yarns or like filamentary materials having a basis of an organic acid ester of cellulose simultaneously with the cake formation whereby improved high tenacity regenerated cellulose yarns may be obtained in an expeditious manner.

Another object of this invention is the provision of apparatus adapted to be employed in connection with the continuous saponification of said stretched organic acid ester of cellulose yarns in cake iorm'.

Uther objects oi this invention will appea from the following detailed description and the accompanying drawing.

In the drawing,

Fig. l is a front elevational view of the apparatus employed in connection with our novel process, partly broken away, showing a spinning bucket in which the stretched organic acid ester of cellulose yarns are received as well as the means for guiding the yarn and for uniformly applying the saponifying solution thereto,

Fig. 2 is a, side elevational view of said device, partly in section, showing the driving mechanism for feeding the yarns to the spinning bucket and the traversing mechanism for the uniform application of the saponifying solution to the yarns in the bucket. and

Fig. 3 is a detail view, in section, of the jacketed yarn guide -rnel through which the saponii'ying solution is introduced.

Like reference numerals indicate like. parts throughout all views of the drawing.

High tenacity regenerated cellulose yarns of an outstanding degree of strength may/be obtained by stretching yarns having a basis of cellulose acetate or other organic acid ester of cellulose, l00, 200, 500 or even 1000 or 2000% of their original length, and then subjecting the stretched yarns to the action of a basic saponifying medium whereby the combined acyl groups are split off. The saponification of the stretched yarns is usually effected after the stretched yarns are taken up in package form, a plurality of yarn packages being placed in a suitable enclosed vessel and the saponifying liquid at the desired temperature then entered therein and maintained in contact with the yarns until saponiflcation is completed. The regenerated cellulose yarns obtained are washed in the vessel and are then rewound on another yarn support since the reduction in the denier of the-yarns due to saponiflcation renders the original yarn package quite soft and therefor unsuitable for further textile operations. The necessity for winding and rewinding the yarn packages and the batch nature of the saponification process has heretofore constituted a substantial problem in attempting to efi'ect the saponification in a more economical manner.

We have discovered that high tenacity stretched yarns having a basis of cellulose acetate or other organic acid ester of cellulose may be saponified in a substantially continuous manner with the elimination of certain winding operations by collecting the cellulose acetate or other organic acid ester of cellulose yams in cake form, directly as they are stretched, in a rotating, perforated spinning bucket while simultaneously applying to the yarn cake collected therein a saponifying medium comprising a solution of a suitable basic saponifying agent, preferably in spray form. By eflecting the saponiflcation of the yarn cake concurrently with the take-up of the stretched cellulose acetate or other organic acid ester of cellulose yarns in cake form, in accordance with, our novel saponification process, completely saponified and twisted high tenacity regenerated cellulose yarns of superior physical characteristics are obtained. The regenerated cellulose yarns produced may then be washed free of the saponifying agent while still in the take-up bucket in the original cake form and the completely saponifled, regenerated cellulose yarns then dried and rewound into any desired package form.

The saponifylng agent, which may be in the form of an aqueous, alcoholic or aqueous/ alcoholic solution of any suitable basic agent, may be sprayed on to the stretched cellulose acetate or other organic acid ester of cellulose yarns in any convenient manner. The saponifying agent may be inorganic in nature such as, for example, sodium hydroxide, potassium hydroxide, sodium silicate, ammonium hydroxide, sodium carbonate or other inorganic basic agent. Organic saponifying agents, such as, for example, methyl amine, ethylene diamine, triethanolamine or other organic bases, may also be employed. The temperature of the solution of saponifying agent applied to the cellulose acetate or other organic acid ester of cellulose yams may vary, with temperatures of from 20 to 100 0. being satisfactory. Preferably, we employ aqueous solutions of sodium hydroxide as the saponifying agent and in concentrations of 0.1 to by weight, the solution being applied to the yarns undergoing saponification at a temperature of from 20 to 90 C. Optimum re-' sults are achieved employing a 2% aqueous solution of sodium hydroxide as the saponifying agent, said solution being maintained at room temperature, i. e. 25 C. during saponiflcation. Preferably, the solution should also contain about 6% to by weight of sodium acetate which aids in avoidin any degradation of the yarn. The cellulose acetate or other organic acid ester of cellulose yarns undergoing saponification should be sub- J'ected to the action of the aqueous saponifying medium for the period of winding plus at least 10 to minutes in addition to complete the desired saponification. Obviously, the yarn first entering the spinning bucket will be subjected to the action of the saponifying liquid for a much greater period of time than the yarns entering later before the latter are completely saponifled and such exposure may encompass a period of as much as 6 to 30 hours. Such extended exposure, however, has not been found to exert a harmful effect on the regenerated cellulose yarns formed.

Referring now to the drawing, in which a preferred embodiment or the apparatus employed in connection with our novel process is shown, a stretched cellulose acetate yarn to be saponified, which yarn is indicated by reference numeral 3, is passed around a fluted feed roller 4 through a pig tail guide 5 and then downward through a jacketed funnel 6 which may be provided with a plurality of constrictions or internal projections 6'. Funnel 6 is caused to reciprocate or traverse along a vertical path by suitable traversing means, to be hereinafter described, and is adapted to guide yarn 3 to the center 'of a rotating spinning bucket 1 whose rotation, in combination with the traverse or funnel 8, causes yarn 3to be taken up and to form windings or cake 8. The upper windings of cake 8 are held in position by means of a springmounted cover I through which funnel 6 passes.

The saponification of yarn cake 8, which step is to be described, is effected in bucket 1. Bucket 1 is provided with a plurality of holes 9, and is firmly seated on the drive shaft l0 ofa high speed electric motor II, the latter being designed to rotate bucket l at speeds up to 7500 R. P. M. or more. Motor II shown) to a source of electric power and is bolted to a bracket I2 by means of a nut I3 threaded on a shaft 14 integral with the motor housing. Bucket I is surrounded by a splash-proof housing I5 provided with a closely fitted cover 16, the base I! or housing l5 being elevated 'at the center, the necessary slope being provided for drainage of saponifying liquid fed thereto to a discharge or drain spout l8. The slope of base l'l prevents any liquid from spilling over through the hole IS in said base through which drive shaft ill, on which the bucket l is seated, passes. The bracket I2, on which the entire bucket, bucket housing and motor assembly is mounted, is carried on framework generally indicated by reference numeral 20.

0nd electric motor 2| suitably mounted beneath framework 20. The rotary power of motor 2| is transmitted through a chain 22 passing around sprockets 23 and 24. Sprocket 24 is keyed to a shaft 25 which is the input shaft of a gear reduction mechanism 26, the output of which is shaft 21. Keyed to shaft 21 are a gear 28 and a sprocket 29. Sprocket 29 meshes with chain drive 30 passing around a sprocket 3|, keyed to shaft 32 and adapted to drive fluted roller 4. Shaft 32 is journaled in

bearings

33 and 34.

Gear 28 meshes with gear 35 keyed to a shaft 36 which shaft drives a heart-shaped cam 3! is provided with connections (not To provide a suitable open type of yarn winding suitably keyed thereto. Riding on cam 31 is a rotatable cam follower 38 set in a feeler arm 39 which is fulcrumed in a bracket 48 mounted on a portion 4| of framework 20. The vertical reciprocating movement imparted to feeler arm 39 by the rotation of cam 31 is transmitted through a link 42 to a pair of spaced, connected

rods

43 and 44 passing through bushing 45 and 46 set in framework 20. The upper portions of

rods

43 and 44 are set in a bar 4I'carrying a pivotally mounted rest 48 in which funnel 5 is supported. The reciprocating vertical movement of rest 48 effected through the action of cam 31, cam feeler arm 39 and

rods

43 and 44 causes funnel 6 to reciprocate and to pay out yarn 3 to bucket l forming cake 8. The desired type of wind is obtained by suitably designing cam 31 to provide the proper traverse of funnel B.

The saponification of the yarn 3 collected in bucket I in the form of a cake 8 is effected by the application thereto of a solution of a suitable basic saponifying agent as heretofore described. The solution of the saponifying agent is fed in through a pipe 49, connected to a suitable source of supply and provided with a valve 58 to control the flow. The liquid passes downward through pipe 49 to a manifold or header 5i having a pressure gauge 5| attached thereto, header 5| being connected to a valve 52 the outlet of which is attached to a flexible tube 53, leading to a side arm 54 of funnel '6. Side arm 54 communicates with a jacket 55 surrounding the center tubular portion 55' of funnel 6 through which yarn 3 passes. Thus, the saponifying liquid does not come in contact with yarn 3 during passage thereof through funnel 6. Jacket '55 is provided with a series of holes 58 at the base thereof and the liquid forced through jacket 55 issues therefrom in the form of'a flne spray. The vertical traversing motion of funnel 6 effected through the medium of the cam mechanism heretofore described serves to distribute the saponifying agent evenly over the windings of cake -8 in bucket 1 without disrupting the lay of the wind. The centrifugal force exerted by the rotation of bucket I at high speed not only assists in causing the saponifying liquid to be distributed evenly and to effect saponification but also to pass through the windings and to be discharged through holes 9 in the side of bucket I. The spray of liquid thrown outward by the centrifugal force of the spinning bucket is contained by housing l5, falls to the sloping base l1 and is discharged through spout l8. When s-aponification is completed, valve 50 may be closed and valves 51 or 58 opened, thus allowing either water or a. suitable neutralizing agent such as a dilute solution of an inorganic acid :to be fed through pipes 59 or 60 to header 5| and then to the windings of cake '8 after passage through Jacket 55 and perforations 56.

The saponifled, regenerated cellulose yarns assoc-re prwuced at the completion of saponification may be removed in the form of a cake by lifting bucket i from shaft l0, releasing cover ,l, overturning the bucket and rapping it sharply. The completely saponified regenerated cellulose yarn may then be taken up in suitable package form by drawing yarns 3 from cake 8, preferably withdrawing said yarns from the outside or cake 0. and reding. The yarns may be employed in any desired textile operation where high tenacity regenerated cellulose yarns of outstanding strength are desired.

The high tenacity, stretched cellulose acetate or other organic acid ester of cellulose yarn d which is passed around fluted feed roller 6 and red to funnel t is preferably thoroughly wetted before being saponified. We have found that a more satisfactory cake may be formed from yarns which have previously been wetted. The stretched yarns may be satisfactorily wetted by immersion in water at room temperature containing 10 to 40% by weight of acetone for 0.1 to 1.0 second during some point in the path of said yarns and prior to entering bucket l.

The yarns undergoing saponification may be l ed to the spinning bucket in which the cake is built up at a rate of 150 to 500 feet per minute with the bucket rotating at 4000 to 10,000 R. P. M. The amount of saponifying liquid being fed in as a spray is correlated to the yarn feed rate and denier and may amount to 50 to 500 ml. per minute. A twist of 1.5 to 6.0 turns per inch may be inserted in the yarns as they are taken up and cakes of completely saponified, high tenacity regenerated cellulose yarn weighing 0.5 to 2 pounds may be produced in each bucket in 6 to 30 hours.

in order further to illustrate our invention but without being limited thereto the following example is given:

Example A Md denier, 120 filament cellulose acetate yarn, which has been stretched ten times its original length, is wet out by being passed through an aqueous bath containing 25% by weight of acetone at room temperature, the yarn being submerged for 0.25 second in the bath. The yarn is then fed at 160 feet per minute into the tunnel of the saponifying device heretofore described. The funnel traverses vertically through 30 complete cycles per minute. The bucket receiving the yarn is rotated at 7000 R. P. M. which action inserts a twist of 3.6 turns per inch in the yarn. The saponifying liquid, comprising a 2.0% aqueous solution of sodium hydroxide containing 6.0% of sodium acetate,.is sprayed on the yarn in the bucket at a rate of 200 ml. per minute at about 20 C. employing a back pressure of 1.25 pounds per sq. inch. A completely saponified cake of high tenacity, regenerated cellulose yarn weighing 0.5 pound is produced in 7.5 hours. The yarn may then be washed, neutralized and washed again while still in cake form by spraying the cake with water, an aqueous solution of a suitable neutralizing agent and then with water again. Yarns of an average dry tenacity of 7.3

grams per denier and an average wet tenacity or 6 grams per denier are obtained. When the same yarn is wound on bobbins prior to saponification and then saponified with the same saponifying medium at the same temperature the regenerated cellulose yarns obtained have an average dry tenacity of 6.5 grams per denier and a wet tenacity of only 5.0 grams per denier.

While the process of our invention has been more particulrly described in connection with the preparation of high tenacity regenerated cellulose yarns by the continuous takeup and saponification of stretched yarns having a basis of cellulose acetate, it maybe employed with equally advantageous results in the saponification of stretched yarns having a basis of other organic acid esters of cellulose. Examples of other organic acid esters of cellulose are, forexample, cellulose propionate and cellulose butyrate as well as mixed organic esters of cellulose such as cellulose acetate-propionate and cellulose acetate-butyrate and mixed cellulose ester-others, e. g. ethyl cellulose acetate.

It is to be understood that the foregoing detailed description is given merely by way of illustration and that many variations may be made therein without departing from the spirit of our invention.

Having described our invention, what we desire to secure by Letters Patent is:

1. In a process for the production of high tenacity regenerated cellulose filamentary materials by a process involving the saponification of high tenacity stretched filamentary materials having a basis of cellulose acetate, the steps which comprise wetting out said stretched cellulose acetate filamentary materials with a 10 to 40% by weight aqueous solution of acetone, taking up said wetted filamentary materials in cake form and effecting the saponification of said filamentary ma terials as said cake is formed by spraying thereon an aqueous solution of sodium hydroxide and continuously removing spent saponifying medium therefrom by applying a centrifugal force to said cake.

2. In a process for the production of high tenacity regenerated cellulose filamentary materials by a. process involving the saponification of high tenacity stretched filamentary materials having a basis of cellulose acetate, the steps which comprise wetting out said stretched cellulose acetate filamentary materials with a 10 to 40% by weight aqueous solution of acetone, taking up said wetted filamentary materials in cake form and eifecting the saponification of said filamentary materials as said cake is formed by spraying thereon an aqueous solution of sodium hydroxide at a temperature of 20 to 90 C. and continuously removing spent saponifying medium therefrom by applying a centrifugal force to said cake.

3. In a process for the production of high tenacity regenerated cellulose filamentary materials by a process involving the saponification of high tenacity stretched filamentary materials having a. basis of cellulose acetate, the steps which comprise wetting out said stretched cellulose acetate filamentary materials with a 10 to 40% by weight aqueous solution of acetone, taking up said wetted cellulose acetate filamentary materials in cake form and effecting the saponification of said filamentary materials as said cake is formed by spraying thereon a 0.1 to 5.0% aqueous solution of sodium hydroxide at a temperature of 20 to 90 C. and continuously removing spent saponifying medium therefrom by applying a centrifugal force to said cake.

4. In bucket spinning apparatus adapted to take up continuous saponifiable filamentary material in cake form and to efiect the saponification thereof, a rotating spinning bucket having perforated side walls for receiving said filamentary material, means for rotating said bucket,

guide means comprising a funnel for guiding said filamentary material to said spinning bucket. means for traversing said funnel to form a cake of filamentary material, said funnel being surrounded by an annular Jacket into which saponi- Number i'ylng medium may be introduced and a plurality 5 ,6 2,291

of orifices circumferentially arranged in the wall at the base of said Jacket for dischargin the saponifying medium as a spray on to the cak of saponifiable filamentary material.

GEORGE W. SEYMOUR. 1o 2053.767

DUSTm Y. MIILER.

REFERENCES CITED file of this patent:

Number 8 UNITED STATES PATENTS Name Date Dreaper May 30, 1922 Bassett et al. Sept. 13, 1927 Wagner July 24, 1928 Dreyfus et al. Mar. 6, 1934 Dickie et al July 17, 1934 Sanders et al. Feb. 12, 1935 Dreyfus Sept. 8, 1936 Dreyfus Jan. 3, 1939 FOREIGN PATENTS Country Date Great Britain Sept. 18, 1930