US2733122A

US2733122A - vixvi o

Info

Publication number: US2733122A
Authority: US
Priority date: 1951-11-30
Publication date: 1956-01-31
Anticipated expiration: 1973-01-31
Also published as: GB711166A; CH333864A

Description

Jan. 31, 1956 L. HERELE ET AL PRODUCTION OF STAPLE FIBRES FROM POLYAMIDES Filed March 5, 1952 6 Sheets-Sheet 1 INVENTORS LU IG HERELE KU JEHLE KA KU PA M5 ER PAUL. SCHLACK THEIR ATTORNEYS Jan. 31, 1956 L. HERELE ETAL 2,733,122

PRODUCTION OF STAPLE FIBRES FROM POLYAMIDES Filed March 5, 1952 6 Sheets-Sheet 2 1 a It 2 A, I 27 Fig. 3 Fig. 3 Fig. 4

INVENTOR5 LUDWIG HERELE KURT JEHLE KARL KUNZ PAUL. MOLLER PAUL SCHLACK THEIR ATTORNEYS Jan. 31, 1956 HERELE 5 AL 2,733,122

PRODUCTION OF STAPLE FIBRES FROM POLYAMIDES Filfld March 5, 1952 6 Sheets-Sheet 3 NVENTORS WIG HEREIJ KURT JEHLE gm KARL- KU PAUL Mbl.

PAUL SCHLACK THEIR ATTORNEYS Jan. 31, 1956 1.. HERELE EI'AL 2,733,122

PRODUCTION OF STAPLE FIBRES FROM POLYAMIDES Filed March 5, 1952 6 Sheets-Sheet 4 INVENTORS LUDWIG- HERELE KURT JEHLE KARL K NZ PAUL M LLER PAUL SCHLkCK WMS HEIR ATTORNEYS Jan. 31, 1956 L. HERELE ETAL 2,733,122

PRODUCTION OF STAPLE FIBRES FROM PQLYAMIDES Filed March 5, 1952 6 Sheets-Sheet 5 INVENTORS LUDWIG HERELE KURT JEHLE 4. KARL K PNZ PAUL MOLLER PAUL SCHLACK THEIR ATTORNEYS Jan. 31, 1956 L. HERELE ETAL 2,733,122

PRODUCTION OF STAPLE FIBRES FROM POLYAMIDES Filed March 5, 1952 s Sheets-Sheet 6 THEIR ATTORNEYS United States Patent M PRODUCTION OF STAPLE FIBRES FROM POLYAMIDES Ludwig Herele, Kurt Jehle, Karl Kunz, Paul Miiller, and Paul Schlack, Bobingen, Germany, assignors to Bobingen Aktiengesellschaft fur Textii-Faser, Bobingen, Germany, a corporation of Germany Application March 5, 1952, Serial No. 274,958 In Switzerland October 5, 1949 Public Law 619, August 23, 1954 Patent expires October 5, 1969 16 Claims. (Cl. 18-54) This invention relates to certain improvements in the production of staple fibres of polyamides.

Staple fibres of linear polyamides can be worked up with good success both in wool and in cotton spinning mills.

In order to ensure smooth spinning of these fibres in the various spinning machines and in order to obtain yarns of a high quality, the staple fibres to be worked besides good technological properties as to tensile strength and elongation must have a definite and durable curliness.

It is an object of the present invention to provide a method by which fibres meeting these requirements can be produced in a reliable and economic manner.

Another object of the invention is to provide a system which permits the production of fibres in accordance with these requirements in a continuous process.

The present invention is based on the observation that in order to meet the requirements above referred to, a specific combination of features regarding the chemical composition of the fibre material and features regarding the physical treatment of such fibres must be adhered to. Therefore, according to the present invention staple fibres are produced from a low of at least 40,000 deniers of polyamides (obtained, for instance, by the process described in detail in the prior Patent 2,241,321 of one of the co-inventors of the present invention) composed substantially of condensation products of the epsilon-aminocaproic acid and still containing watersoluble monomers or lowly polymeric compounds, by the steps of stretching the tow continuously to a multiple of its length, washing it out with hot Water, treating it with a softening agent, if desired, while being under tension, drying to a degree of moisture of less than percent, preferably less than 4 percent while maintaining the tension, crimping by a mechanical process and at elevated temperature, preferably by stufiing, and finally cutting the filaments to the desired staple length, whereupon the staple fibres can immediately be opened by blowing at them a jet of air, and discharged said steps directly succeeding each other in this order, in a continuous process.

For the purpose of the present specification the term condensation products of the epsilon-aminocaproic acid" is intended to include not only filaments obtained by the condensation of aminocaproic acid but also filaments obtained by other processes, more particularly by the polymerisation of epsilon-caprolactam which is sometimes referred to as a polyamide-forming derivative of the aminocaproic acid, provided only that the resulting filaments have a chemical structure which is identical to that obtained by the condensation of the epsilon-aminocaproic' acid. By way of alternative, the polyamides in question could be defined as polyamides of the type yielding the hydrochloride of the aminocaproic acid when subjected to hydrolysis with hydrochloric acid.

Our novel process starts from a tow containing watersoluble monomeric and/ or water-soluble lowly polymeric 2,733,122 Patented Jan. 31, 1956 constituents, generally in quantities of 4 to 15 percent by weight. Hence, it is not necessary to remove the monomeric and the lowly polymeric constituents before spinning the polyamide, but it is also possible to apply the method to polyamide fibres whose contents of watersoluble constituents has been reduced to less than 4 percent by special measures during the continuous polyierisation process, for instance, by vacuum evaporation or by extraction of the polyamide before the working-up by the well-known process of melting the material on a grid. Preferably tows are used which have been obtained by direct spinning of continuously produced melts of polymers.

The process according to the invention will at first be described in a general way:

The filaments drawn Off from the rolls coming from the spinning machine are united to form a bundle of parallel filaments which are at first continuously oriented in conventional manner by stretching between roller aggregates. In case of stretching without heating a draft of about 123.5 to 1:45 is to be applied. Advantageous ly the tow is additionally stretched at an elevated temperature, e. g., between and In this case, owing to the facilitation of the molecular flow a higher draft of about 1:4.5 or 125.5 can be applied and it is possible to stretch each fibre to a particularly fine titre, e. g., of 1.2 to 2 den. Moreover, this method offers further advantages which will be hereinafter explained.

After the stretching the filament tow is passed under tension through hot, preferably boiling water in order to wash out the water-soluble constituents from the filaments. Textile treating agents, such as wetting and dispersing agents, may be added to the hot water in order to remove from the filaments the finishing agents originating from the spinning process. In some instances, solvents may be used instead of water. The washing time may be, for instance, 60 to 300 seconds, depending'on the thickness of the filament bundles.

Following the washing process the filament bundles may be treated with other agents in one or more further vats, e. g., with oiling or softening agents, tanning agents, or dyestuffs. These treatments also are carried out while the filament tow is under tension, preferably maintaining the circumferential speed of the first treating roller which in turn is usually somewhat reduced in relation to the circumferential speed of the stretching frame, in order to equalize the preliminary tension originating from the stretching process. In this connection it should be noted that by way of alternative the oil or softener required for the further treatment of the fibre may be applied entirely or partly after the cutting. The softening agents may consist of stea'ryl polyglycol, polyglycolether from the alcohols obtained by reduction of mixtures of fatty acids from palm kernels, if desired in connection with salts improving the antistatic effect, such as, magnesium chloride, sodium nitrate, triethanol amine-lactate. The deposits of softening agents on the fibre are in general between 0.4 and 1 percent by weight.

The filament tow is then further dried under tension to an amount of moisture of less than 10% and either sub jected to a second stretching treatment, at an elevated temperature, or immediately crimped mechanically at an elevated temperature, e. g., by gear wheels, or preferably by stufiing. The material which still shows internal tensions is preferably crimped at a temperature above 80' ing between 80 C. and 130 C. It is also possible to apply high frequency heating. Finally, the continuous filaments are cut to staple length. The staple fibres may be opened individually by blowing with a brisk air current and delivered to a store tank. The tension to be maintained from the stretching up to the feeding of the filaments to the curling device may vary within certain limits, depending on the desired type of fibre. The tension required for producing a fibre of the wool type is less than that required for a fibre of the cotton type. erally speaking, it can be said that the tension of a stretched filament bundle of 40,000 denier amounts to about 140 kilograms after the stretching and before the washing. After the washing and before the drying the tension of the humid cable is about 100 kilograms, and after the drying it rises again to 150 kilograms.

Our novel process is particularly advantageous since it permits the production, in a continuous process starting from the stretching, of a permanently curly fibre tuft. Thus, the conventional devices for opening, e. g., pickers or shakers and the like, can be dispensed with. Our novel method permits the production of a fibre having a relatively low breaking dilatation or elongation at rupture without a detrimental effect to the fibre. Moreover, the curly fibre obtained according to the present invention is more suitable for an after-treatment with tanning agents than a comparable fibre which after the crimping contains monomeric lactam in quantities, for instance, of 5 percent or more.

All percentages or proportions in the specification and claims are by weight, temperatures in Celsius.

Our novel process is equally suitable for the production of long-stapled fibre with any form of crimps adapted for working up after the worsted spinning process and for short-fibred and possibly less intensively crimped material to be worked up after the methods used in the cotton and schappe spinning mills. With curly staple fibres of the cotton type produced from polymeric epsiloncaprolactam by conventional processes, it has been ob served that only a relatively light crimping in connection with a tanning treatment, e. g., with tannin or with synthetic oxysulfon tanning agents permitted the passage through the carding machine while it was now found that fibres produced by our novel process being treated with tanning agents but being crimped relatively intensively show a more favorable behaviour than less intensively crimped fibres as to their stability in the carding operation. In order to produce a particularly fine fibre material, e. g., of a single titre of 1.2 to 2.0 denier, adapted for working up according to the silk and cotton spinning system, the tow according to the invention is preferably stretched in a hot condition, e. g., between 140 C. and 135 C., and with a high stretching ratio, e. g., of 1 :4 to 1:55. In this case it may be advisable to attenuate the very high preliminary tension by a somewhat higher reduetion of the circumferential speed or delivery of the treating rollers compared to the delivery of the stretching device.

It will be understood that the operations following the crimping of the thus treated filaments, i. e. the cutting and opening, can also be. carried out, in a sequence of operans p ately om the pre ed n a m nt s t the place and time of the treatment, if desired, provided that the crimped filaments are stored and transported in such a way that the crimping is not impaired thereby. However, it is important that the process up to this stage, i. e. including the crimping operation, is carried out in a continuous series of operations directly succeeding each other, not only for economic reasons, but also because it is important to adapt the, residual moisture of the tow, which can. easily be controlled in the drying operation, to the actual requirements of the crimping operation. The crimping will be increased with increasing moisture in case of unchanged pressure and moreover the lustre of the flocks is reduced so that the material obtains a char- Genacter more similar to wool. Moreover, the method offers the advantage that the material heated on the drying cylinder to about C. is fed directly into the crimping equipment, whereby less heating of the crimping equipment is required.

In order to obtain an approximately uniform crimping efiect with increased moisture, it is necessary, in case of unchanged pressure, to slightly reduce the temperature. The upper temperature limit which is defined by the beginning of agglutination, is reduced with increasing moisture in the cable.

We have found that the quality of the crimping can also be improved by allowing the fibre material leaving the stufiing apparatus in a hot condition to stay in a discharge channel directly following the stuffing channel, while maintaining the compressed shape, for a short time, about 1 to 2 minutes, with gradual cooling, before exposing it to the draft of the cutting device.

Our novel process is preferably carried out by a system comprising a per se known stretching frame having two roller aggregates driven at different speeds, which may be followed by a second stretching frame operating at elevated temperature, and/or means for a wet treatment of the fibres under tension, at least one vat for liquid treatment with cylindrical rotary feed members arranged therein transversely to the travelling direction of the filament tow, which feed members may be in the form of smooth rollers, cylindrical case drums or shaft drums; a rotary drying cylinder, which can be heated, a crimping device, more particularly of the stuffing type, comprising a pair of feed rollers, a stuffing chamber which inludes heating means, a weight-loaded retaining flap and a discharge channel; and a cutting device of any suitable type arranged directly behind the crimping device. The vat or vats for liquid treatment may be substituted by one or more gutters which are provided with several deflection rollers in order to pass the filament bundle through the gutters for a sufficient length of time.

It is preferred to provide on the way of the filament tow from the last fibre treating device to the drying cylinder an instrument for controlling the tension of the filaments. A braking device acting by deflection of the travelling direction of the filaments may be inserted between the crimping device and the cutting device, for instance, in the form of a creel brake, trellis grate, band brake or claw brake. It has been found that this type of braking provides a simple compensation for the loops possible forming in the filaments leaving the crimping device.

The heating of the stuffing chamber can be achieved in any suitable manner, e. g., by a steam jacket or by electric resistance heating. It is also contemplated within the purview of this invention to provide the stufiing chamber with a high frequency heating which permits a particularly uniform heating of the filaments conglomerated in the chamber. A pneumatic device for opening and delivering the staple fibre may be joined to the cutting device. The air current used for opening, simultaneously may serve to treat the fibres with softening and conditioning agents or antistatically acting substances, by injecting the respective agent into the inlet channel of the receiving tank, shortly before the fibres enter into the tank itself. The loose fibre mass obtained in this manner in many instances on compression into bales may be manufactured into slivers without a combing process, merely by a carding treatment.

Further objects, features, and details of the invention will be seen from the following detailed description in connection with the accompanying drawings, showing some embodiments of apparatuses and equipments adapted for carrying out the invention, and which:

Fig. 1 is a diagrammatic view of a system adapted for carrying out the method according to the present invention,

Fig. 2 is a longitudinal section, on a larger scale, of the crimping device forming part of the system of Fig. 1,

Fig. 3 is a section online IIIIII of Fig. 2,

Fig. 4 is a section on line IVIV of Fig. 2,

Fig. 5 is a side view showing another form of a crimping device, using toothed wheels,

Fig. 6 is a section on line VIVI of Fig. 5,

Fig. 7 is a diagrammatic view of a modification of the system shown in Fig. 1,

Fig. 8 is a longitudinal section of one embodiment of the heating device diagrammatically shown in Fig. 1,

Fig. 9 is a section on line IXIX of Fig. 8, on a larger scale,

Fig. 10 is a side elevation, partly in section, showing a modification of the heating device diagrammatically shown in Fig. 1,

Fig. 11 is a section on line XI-XI of Fig. 10,

Fig. 12 is a diagrammatic section of a further modification of the heating device diagrammatically shown in Fig. 1,

Fig. 13 is a section on line X[IIXIII of Fig. 12,

Fig. 14 is a diagrammatic plan view of a modified washing device, and

Fig. 15 is a section on line XV-XV of Fig. 14, drawn on a larger scale.

Similar reference numerals denote similar parts in the different views.

Referring now to the drawings, and first to Fig. 1, it will be seen that according to this embodiment the filaments drawn from the rolls 1 and combined into a tow 2 are stretched between the

roller systems

3 and 4, the stretching zone being heated to the required temperature by a heating device 5, if desired, e. g., by infrared radiators, as will be hereinafter described. The filament tow 2 then passes over two rollers 7 rotating in a washing vat or tub 6, the layering of the fibres in parallel turns being ensured through a comb 8. The tow then passes into the tray 10 provided with deflecting rollers 9 where it is provided with a softener and delivered to a drying cylinder 11 including a guide roller 12 and a separating comb 13. On leaving the drying cylinder the tow 2 is seized by the

feed rollers

14, 14 of the crimping device 14-20 shown in greater detail in Figs. 2 to 4. Roller 14 has a projecting flange 26 projecting into a pcripheral groove 27 of roller 14', for safe engagement and driving of the tow 2 passing through the groove as shown and being forced into the stufiing channel 17 which is heated by electrical heating means 15, 16, accommodated in the space 28 defined by the outer jacket 29, and resiliently closed by a retaining flap 19 which is urged against the mouth end of the channel 17 by a weighted lever 18. The electrical heating means may be adapted for high frequency heating of the filaments. It will thus be understood that the filaments 2 under the stufiing action exerted by the rollers 14, 14' are curled or crimped in the channel 17 and as the stuffing pressure exerted by the filament bundle is increasing, the retaining flap 19 will be raised, allowing the stuffed filaments to enter into the cooling channel 20, Fig. 1, from which the filaments are drawn through a thread braking device 21 in which the filaments are forced to take a zig-zag course, into a cutting device 22 in which the filaments are cut to the desired staple length. The staple cuts 23 occurring in this device are pneumatically seized by the brisk air current indicated by the arrow 24, dispersed and conducted in a well opened condition, into the store tank 25 which is covered by a wire screen. The material collected therein is compressed into bales and is now ready for dispatch. In many instances it can be worked up without combing.

Figs- 5 and 6 show a modified device for crimping the fibres, comprising gear wheels and 31 meshing with each other with a slight spacing between the intermeshing teeth, so as to prevent injury to the filaments by too intensive compression during their passage between the intermeshing teeth. The

gear wheels

30 and 31 are made hollow and traversed by steam, hot air or any other 1 store tank 25.

heating agent passed through

tubes

32, 33 connected to the gear wheels by suitable stuffing boxes 34.

A modified process according to the invention will now be described with reference to Fig. 7 in which the devices corresponding to the plant of Fig. 1 are designated with identical reference numerals. In this case, the filaments after the stretching between the roller aggregates 3 and 4 are subjected to a further stretching action between the roller aggregates 4 and 35, under action of heat produced by a heating device 43 which will be hereinafter described in greater detail. The filament tow is then passed through a tank 37 for wet heat treatment. The tank 37 may be filled with water or with any suitable treating liquid which is heated by a heating device 41. Roller aggregates 38, 39, and 40 serve to guide the filament tow and to impart thereto a suitable tension which may be different between the roller aggregates 38 and 39 on one hand and between the roller aggregates 39 and 40 on the other hand. The roller aggregate 39 can be adjusted in the direction of the arrows so as to vary the relative lengths of the operating paths 38-39 and 39-40 exposed to different stretching forces, or in other words, to vary the period of time during which the filament tow is exposed to the different tensions. For the rest of the process the filaments are treated in the same way as described With reference to Fig. 1, except that an injector device 42 is shown by which a softening agent can be sprayed onto the staple fibres as they are blown into the Under action of the air current blown in at 24 the softening agent is uniformly distributed over the surface of the fibres.

Various possible forms of the heating device 43 will now be described in greater detail with reference to Figs. 8, 9, or 10, 11, or 12, 13, respectively. Referring at first to Figs. 8 and 9, it will be seen that the tow 2 is passed through a heating chamber 43, located between the roller aggregates 4 and 35. The heating chamber 43 comprises a lower part 43' and an upper part 43" which is hinged to the lower part by a hinge indicated at 44 so as to facilitate opening of the heating chamber, e. g., by winding up a pull rope 45 on a spindle 46. Heat-insulating material 47 is provided between the inner and outer walls of the heating chamber 43, and infrared radiators 48 are secured to the inner walls of the heating chamber. Said infrared radiators may be ofany suitable type. For instance, ceramic resistances may be used, consisting of a ceramic resistance material, or of resistance wire or semi-conductors embedded in ceramic material.

According to Figs. 10'and 11, infrared lamps 49 are provided in a heating chamber 43. The wave length of the heat radiation of the lamps 49 should be adapted to the absorption characteristics of the fibre material to be treated.

According to Figs. 12 and 13, the filament tow 2 is passed through a heating chamber 43 which is heated by heating coils 50 screened by screening walls 51, and additionally heated by a fiow of hot inert gas circulated through a pipe system 52, under action of a blower 53, and heated by heating coil 54. An inlet branch including a throttle flap 56 and an outlet branch 57 serve to renew the gas in the pipe, system. j

Figs. 14 and 15 show a washingdevice .of the gutter type which may be provided instead of the washing tank 6, 7, 8, shown in Figs. 1 and 7. In this case, the filament tow is passed through gutters 58, over deflecting rollers 59, and rinsed by hot water or another liquid treating agent dripping onto the filaments from sprinkling pipes 60 which, as shown in Fig. 15, are arranged above their gutters, these parts being shown tilted by in Fig. '14 to permit a clear illustration. The water is collected in the gutter 58 and discharged'through thepipe system 61 as diagrammatically indicated by the respective arrows.

Some practical examples of carrying out the invention will now be described, referring to the drawings by the respective reference numerals.

Example 1 A filament tow of a total titre of 200,000 den. and a single titre of 16 den., produced of polymeric epsiloncaprolactam by continuous polymerisation and subsequent spinning of the melt containing percent of monomeric and lowly polymeric lactam is stretched between the two

roller aggregates

3, 4, at a ratio of 1:4.0 to a single titre of 4.0 den. and then passed, with a reduction of speed of 6%, caused by a correspondingly lower speed of the drawing-off roller, and at a speed of 40 meters per minme, over the two rollers 7 rotating in the washing tank 6, in which the tow is treated with boiling water for a period of 80 seconds, whereby the spinning preparations and the water-soluble constituents of the fibre substance are dissolved, the latter down to about 1.5% by weight. From the washing tank the tow is drawn at the same speed into the tank 10 provided with deflecting rollers 9 and on this occasion is provided with about 0.5 percent by weight of a conventional softening agent. The temperature of the bath with the softening agent amounts to 35 C. Then it passes to the drying cylinder 11 rotating at the same speed and heated by steam to a surface temperature of 115 C. After a treatment period of 60 seconds the tow enters with an amount of moisture in the cable of 3.0 percent into the chamber 17 of the crimping device which is heated to 125 C. (wall temperature). The crimped, largely conglomerated, still hot material is forced through the discharging channel 20 while maintaining the curliness, i. e., without draft, and then drawn into the cutting machine 22 through the braking device 21. The staple fibres of 100 millimeters length obtained by the cutting are blown into the store tank 25 and then compressed into bales. The fibre material thus obtained can be worked up into top and spun in normal manner. It is even possible, in case of medium numbers of yarn, to do with cards only, since the fibre is pure and free from neps.

Example 2 I The fibre material is treated in the same way as described with reference to Fig. 1, but the period of drying on the drying cylinder 11 is reduced to 25 seconds. The tow running off from the drying cylinder 11 has a moisture of 5.5 percent by weight. It is possible to obtain a titre of a dull lustre which is very similar to wool. The curliness of the fibre (about 10 crimps per centimeter) is very fast to boiling.

Example 3 A filament tow of polymeric epsilon-caprolactam with :1 contents of water-soluble constituent of 11 percent by weight, with a total titre of about 200,000 den. and a single titre of 8 den. is stretched in the same way as described in Example 1 wiLh a ratio of 1:4, to a single titre of 2 den., and then treated in the same way as described in Example 1. The filaments arrive at the crimping device 15 with an amount of moisture of about 2.5%. After the crimping the filaments are cut to a staple length of 40 millimeters. The material thus obtained'can be worked up to card sliver according to the cotton spinning process without preceding treatment with tannin.

Example 4 The filament tow is treated as in Example 3, except that the time of stay on the drying drum 11 is reduced to 25 seconds as per Example 2. The material which has been crimped with an amount of moisture of about 5% shows a highe sta ili y and can be ked pon th rd n better th n tha ma e ac ording to Ex mpl Ea cample 5 A fila ent to o polymeric eps aprola tam o a total titre of 170,000 den. is stretched at a temperature of 8 170 and a ratio of 115.3 to a single fibre titre of 1.5 den. and treated further as per Example 4. The finely crimped fibre can be worked up in the fiat card without treatment with tannin and can be spun into fine threads of a particularly high tensile strength.

Example 6 The filaments are treated as per Example 1, but using a filament tow of a total titre of 400,000 den., so that the titre of the bundle on stretching amounts to 100,000 den. The tow 2 coming from the drying cylinder 11 with a temperature of C. and an amount of moisture of 2.3 percent is passed into the stuffing chamber 17 of the crimping device which has been heated to 50 C. The stuffing chamber is 30 mms. high, 30 mms. wide and mms. long. The load on the retaining flap 19 is adapted so that a specific pressure of 6.2 kilograms per centimeter square, referring to the cross section at right angles to the axis of the stufiing channel, is exerted on the tow in the stuifing channel. After the cutting, a very curly material is obtained which can be spun into particularly full yarns.

Example 7 The fibre material is treated as per Example 6, except that the stuffing channel 17 of the crimping device has a length of 600 millimeters and the retaining flap 19 is opened. Owing to the friction occurring in the long stuifing chamber 17 a sufficient retaining pressure is produced, even though the flap 19 is open, so that the filaments discharged from the crimping device have a good curliness.

Example 8 The fibre material is treated as per Example 6, except that the tow coming from the drying cylinder and having a temperature of 110 C. and an amount of moisture of 0.8 percent only, is introduced into a crimping device whose stuffing chamber 17 is treated to 50 C. and has a length of 60 millimeters, a width of 15 millimeters, and a height of 15 millimeters. The load on the retaining flap 19 is adapted so that the specific pressure in the stuffing chamber 17 amounts to 13.3 kilograms per centimeter square, referring to the cross section at right angles to the axis of the stuffing channel. The curliness of this fibre corresponds to that mentioned in Example 3.

While the invention has been described in detail with respect to certain now preferred examples and embodiments of the invention it will be understood by those skilled in the art after understanding the invention that various changes and modifications may be made without departing from the spirit and scope of the invention and it is intended, therefore, to cover all such changes and modifications in the appended claims.

What is claimed is:

1. A method of producing staple fibres from filaments of polyamides composed substantially of condensation products of the epsilon-aminocaproic acid containing water-soluble compounds or" the group consisting of monomeric and lowly polymeric compounds, comprising the steps of combining the filaments into a tow of at least 40,000 deniers, placing a tension on said tow to stretch the filaments to a multiple of their length, washing the tow with a hot aqueous washing agent, substantial drying the tow to a degree of moisture of less than 6%, said washing and drying being performed while tension is maintained on said tow, crimping the filaments in a continuous mechanical crimping process at a temperature above room temperature while maintaining the moisture content at less than 6%, said steps directly succeeding each other in this order, in a continuous process cutting the to into s pl fibres nd op ning the stapl fibres by aetion of a jet of air blown at the fibre material.

A m h d of p du i g ap fibres from xtruded. freshly formed filaments of polyamides composed substantially of condensation products of the epsilon-aminoca; proic acid containing water-soluble compounds of the group consisting of monomeric and lowly polymeric compounds, comprising the steps of combining the filaments into a tow of at least 40,000 den., placing a tension on said tow to stretch the filaments to a multiple of their length, washing the tow with a hot aqueous washing agent, substantial drying the tow said washing and drying being performed while tension is maintained on said tow, crimping the filaments in a continuous mechanical crimping process at a temperature while maintaining the substantial dryness thereof above room temperature, and cutting them into staple fibres which are opened by action of a jet of air blown at the fibre material, said steps directly succeeding each other in this order, in a continuous process.

3. A method of producing staple fibres from filaments of polyamides composed substantially of condensation products of the epsilon-aminocaproic acid containing monomeric caprolactam, comprising the steps of combining the filaments into a tow of at least 40,000 deniers, placing a tension on said tow to stretch the filaments to a multiple of their length, washing the tow with a hot aqueous washing agent, substantial drying the tow to a degree of moisture of less than 6% said washing and drying being performed while tension is maintained on said tow, crimping the filaments in a continuous mechanical crimping process at a temperature above room temperature while maintaining the moisture content at less than 6%, said steps directly succeeding each other in this order, in a continuous process cutting the tow into staple fibres and opening'the staple fibres by action of a jet of air blown at the fibre material.

. 4. A method of producing staple fibres from filaments of polyamides composed substantially of condensation products of the epsilon-aminocaproic acid containing water-soluble compounds of the group consisting of monomeric and lowly polymeric compounds, comprising the steps of combining the filaments into a tow of at least 40,000 deniers, placing a tension on said tow to stretch the filaments to a multiple of their length, washing the tow with a hot aqueous washing agent, subjecting it to a softening treatment, substantial drying the tow said washing, softening and drying being performed while tension is maintained on said tow, crimping the filaments in a continuous mechanical crimping process at'a temperature above room temperature while maintaining the substantial dryness thereof, said steps directly succeeding each other in this order, in a continuous process cutting the tow into staple fibres and opening the staple fibres by action of a jet of air blown at the fibre material.

5. A method of producing staple fibres from filaments of polyamides composed substantially of condensation products of the epsilon-aminocaproic acid containing water-soluble compounds of the group consisting of monomeric and lowly polymeric compounds, comprising the steps of combining the filaments into a tow of at least 40,000 deniers, placing a tension on said tow to stretch the filaments to a multiple of their length, washing the filaments with a hot aqueous washing agent, and then substantially drying the tow to a degree of moisture of less than 4% said washing and drying being performed while tension is'maintained on said tow, crimping the filaments in a continuous mechanical crimping process at a temperature above room temperature while maintaining the moisture content at less than 4%, said steps directly succeeding each other in this order, in a continuous process, cutting the tow into staple fibres and opening the staple fibres by action of a jet of air blown at the fibre material.

6. A method of producing staple fibres from filaments of polyamides composed substantially of condensation products of the epsilon-aminocaproic acid containing water-soluble compounds of the group consisting of monomeric and lowly polymeric compounds, comprising the steps of combining the filaments into a tow of at least 40,000 deniers, placing a tension on said tow to stretch the filaments to a multiple of their length, washing the tow with a hot aqueous washing agent, substantially drying the tow to a degree of moisture of less than 6% said washing anddrying being performed while tension is maintained on said tow, crimping the filaments in a continuous mechanical crimping process at a temperature above room temperature while maintaining the moisture content at less than 6% by stufiing, said steps directly succeeding each other in this order, in a continuous process, cutting the tow into staple fibres and opening the staple fibres by action of a jet of air blown at the fibre material.

7. A method of producing staple fibres from filaments of polyamides composed substantially of condensation products of the epsilon-aminocaproic acid containing water-soluble compounds of the group consisting of monomeric and lowly polymeric compounds, comprising the steps of combining the filaments into a tow of at least 40,000 deniers, placing a tension on said tow to stretch the filaments to a multiple of their length, washing the tow with a hot aqueous washing agent, substantially drying the tow said washing and drying being performed while tension is maintained on said tow, crimping the filaments in a continuous mechanical crimping process at a temperature and while maintaining the substantial dryness thereof above room temperature, cutting them into staple fibres which are opened by action of a jet air blown at the fibre material, and treating the fibres with a softening agent in the same operation, said steps directly succeeding each other in this order, in a continuous process.

8. A method of producing staple fibres from filaments of polyamides composed substantially of condensation products of the epsilon-aminocaproic acid containing water-soluble compounds of the group consisting of monomeric and lowly polymeric compounds, comprising the steps of combining the filaments into a tow of at least 40,000 deniers, placing a tension on said tow to stretch the filaments to a multiple of their length, at least the last phase of said stretching treatment being carried out at an elevated temperature of the filaments, washing the tow with a hot aqueous washing agent, substantially drying the tow said washing and drying being performed while tension is maintained on said tow, crimping the filaments in a continuous mechanical crimping process at a temperature above room temperature while maintaining the substantial dryness thereof, said steps directly succeeding each other in said order, in a continuous process, cutting the tow into staple fibres and opening the staple fibres by action of a jet of air blown at the fibre material.

9. A method of producing staple fibres from filaments of polyamides composed substantially of condensation products of the epsilon-aminocaproic acid containing water-soluble compounds of the group consisting of monomeric and lowly polymeric compounds, comprising the following steps, succeeding each other in this order, in a continuous process: combining the filaments into a tow of at least 40,000 deniers, placing a tension on said tow to stretch the filaments to a multiple of their length, at least the last phase of said stretching treatment being carried out at an elevated temperature of the filaments, washing the tow with a hot aqueous washing agent, substantially drying the tow, stretching once more at an elevated temperature of the filaments, said washing, drying and last mentioned stretching being performed while tension is maintained on said tow crimping the filaments'at a temperature above room temperature while maintaining the substantial dryness thereof, and cutting them into staple fibres which are opened by action of a jet of air blown at the fibre material.

10. A method of producing staple fibres from filaments of polyamides composed substantially of condensation products of the epsilon-aminocaproic acid containing water-soluble compounds of the group consisting of monomeric and lowly polymeric compounds, comprising the steps of combining the filaments into a tow of at least 40,000 deniers, placing a tension on said tow to stretch the filaments to a multiple of their length, washing the tow with a hot aqueous washing agent, substantially dry- '11 ing the tow said washing and drying being performed while tension is maintained on said tow, crimping the filaments ina continuous mechanical crimping process at a temperature above room temperature by stuffing while containing 6 to 0.5% by weight of moisture and having a temperature of 80 to 130 C., said steps directly succeeding each other in this order, in a continuous process, cutting the tow into staple fibres and opening the staple fibres by action of a jet of air blown at the fibre material.

11. A method of producing staple fibres from filaments of polyamides composed substantially of condensation products of the epsilon-aminocaproic acid containing 9 to 12% by weight of epsilon caprolaetam and water-soluble low polymers, comprising the steps of combining the filaments into a tow of at least 40,000 deniers, placing a tension on said tow to stretch the filaments to a multiple of their length, washing the tow with a hot aqueous Washing agent, substantially drying the tow, said washing and drying being performed while tension is maintained on said tow, crimping the filaments in a continuous mechanical crimping process at a temperature while maintaining the substantial dryness thereof above room temperature, said steps directly succeeding each other in this order, in a continuous process, cutting the tow into staple fibres and opening the staple fibres by action of a jet of air blown at the fibre material.

12. A method of producing staple fibres from filaments of polyamides composed substantially of condensation products of the epsilon-aminocaproic acid containing water-soluble compounds of the group consisting of mono meric and lowly polymeric compounds, comprising the steps of combining the filaments into a tow of at least 40,000 deniers, placing a tension on said tow to stretch the filaments to a multiple of their length, washing the tow with a hot washing agent containing additional treating agents, substantially drying the tow to a degree of moisture of less than 6% by weight said washing and drying being performed while tension is maintained on said tow, crimping the filaments in a continuous mechanical crimping process at a temperature above room temperature while maintaining the moisture content at less than 6%, said steps directly succeeding each other in this order, in a continuous process, cutting the tow into staple fibres and opening the staple fibres by action of a jet of air blown at the fibre material.

13. A method of producing staple fibres from filaments of polyamides composed substantially of condensation products of the epsilon-aminocaproic acid containing water-soluble compounds of the group consisting of monomeric and lowly polymeric compounds, comprising the steps of combining the filaments into a tow of at least 40,000 deniers, placing a tension on said tow to stretch the filaments to a multiple of their length, washing the tow, with a hot washing agent containing a wetting agent, substantially drying the tow said washing and drying being performed while tension is maintained on said tow, crimping the filaments in a continuous mechanical crimping process at a temperature and while maintaining the substantial dryness thereof above room temperature, said steps directly succeeding each other in this order, in a continuous process, cutting the tow into staple fibres and opening the staple fibres by action of a jet'of air blown at the fibre material.

14, A method of producing staple fibres from filament; of polyamides composed substantially of condensation products of the epsilon-.aminocaproie acid containing was tor-soluble compounds of the group consisting of mono: meric and lowly polymeric compounds, comprising the steps of combining the filaments into a tow of at least 40,000 deniers, placing a tension on said'tow to stretch the filaments to a multiple of their length, washing thG tow, with a hot washing agent containing a dispersing agent, substantially drying the tow said washing and drying being performed while tension is maintained on said tow, crimping the filaments in a continuous mechanical crimping process at a temperature and while maintaining the substantial dryness thereof above room temperature, said steps directly succeeding each other in this order, in a continuous process, cutting the tow into staple fibres and opening the staple fibres by action of a jet of air blown at the fibre material.

15. A method of producing staple fibres from filaments of polyamides composed substantially of condensation products of the epsilon-aminocaproic acid containing water-soluble compounds of the group consisting of mono-. meric and lowly polymeric compounds, comprising the steps of combining the filaments into a tow of at least 40,000 deniers, placing a tension on said tow to stretch the. filaments to a multiple of their length, washing the tow with a hot aqueous washing agent, substantially drying the tow said washing and drying being performed while tension is maintained on said tow, crimping the filaments in a continuous mechanical crimping process at a temperature while maintaining the substantial dryness thereof above room temperature, and cutting them into staple fibres which are opened by action of a jet of air blown at the fibre material and treated with conditioning agents, said steps directly succeeding each other in this order, in a continuous process.

16. A method of producing staple fibres from filaments of polyamides composed substantially of condensation products of the epsilon-aminocaproic acid containing water-soluble compounds of the group consisting of monomeric and lowly polymeric compounds, comprising the steps of combining the filaments into a tow of at least 40,000 deniers, placing a tension on said tow to stretch the filaments to a multiple of their length, washing the towwith a hot aqueous washing agent, substantially drying the tow said washing and drying being performed while tension i maintained on said tow, crimping the filaments in a continuous mechanical crimping process at a temperature above room temperature while maintaining the substantial dryness thereof, and cutting them into staple fibres which are opened by action of a jet of air blown at the fibre material and treated with antistatic agents, said steps directly succeeding each other in this order, in a continuous process.

References Cited in the file of this patent UNITED STATES PATENTS Miles Apr. 23, 1940 Hooper Apr. 11, 1944 OTHER REFERENCES

Claims

1. A METHOD OF PRODUCING STAPLE FIBRES FROM FILAMENTS OF POLYAMIDE COMPOSED SUBSTANTIALLY OF CONDENSATION PRODUCTS OF EPSILON-AMINOCAPROIC ACID CONTAINING WATER-SOLUBLE COMPOUNDS OF THE GROUP CONSISTING OF MONOOMERIC AND LOWLY POLYMERIC COMPOUNDS, COMPRISING THE STEPS OF COMBINING THE FILAMENTS INTO A TOW OF AT LEAST 40.000 DENIERS, PLACING A TENSION ON SAID TOW TO STRETCH THE FILAMENTS TO A MULTIPLE OF THEIR LENGTH, WASHING THE TOW WITH A HOT AQUEOUS WASHING AGENT, SUBSTANTIAL DRYING THE TOW TO A DEGREE OF MOISTURE OF LESS THAN 6%, SAID WASHING AND DRYING BEING PERFORMED WHILE TENSION IS MAINTAINED ON SAID TOW, CRIMPING THE FILAMENTS IN A CONTINUOUS MECHANICAL CRIMPING PROCESS AT A TEMPERATURE ABOVE ROOM TEMPERATURE WHILE MAINTAINING THE MOISTURE CONTENT AT LESS THAN 6%, SAID STEPS DIRECTLY SUCCEEDING EACH OTHER IN THIS ORDER, IN A CONTINUOUS PROCESS CUTTING THE TOW INTO STAPLE FIBRES AND OPENING THE STAPLE FIBERS BY ACTION OF A JET OF AIR BLOWN AT THE FIBRE MATERIAL.