US3548462A - Process for the preparation of a fiber arrangement or strand composed of staple fibers for undergoing a subsequent high draft - Google Patents

Description

Dec. 22, 1970 w. NAEGELI 3,548,462

PROCESS FOR THE PREPARATION OF A FIBER ARRANGEMENT OR STRAND COMPOSED OF STAPLE FIBERS FOR UNDERGOING A SUBSEQUENT HIGH DRAFT Filed Feb. 4. 1965 INVENTOR. WERNER IVAE3EL) 62mm? WM V United States Patent Oflice U.S. Cl. 19-150 24 Claims ABSTRACT OF THE DISCLOSURE A stable band is formed from a fiber arrangement of staple fibers which, for instance, consist of a card web. The stable band can be subsequently subjected to a faultless high draft. The stable band is formed in that the fiber arrangement of staple fibers is imbued with a liquid adhesive, such is then squeezed out and the fiber arrangement is condensed at all sides, with there undergoing a setting of the liquid adhesive after the aforementioned condensing operation of the fiber arrangement. Consequently, there is produced a compact stable band possessing a homogenous bonding and capable of being effectively drafted.

The present invention has reference to an improved process for the preparation of a fiber arrangement or strand composed of staple fibers for undergoing a subsequent high draft as well as having reference to an improved stable band produced according to the aforesaid process.

First of all, there will be defined the terminology employed herein for the different structures formed of staple fibers:

Thus, the term spinning-band denotes a conventional, non-twisted sliver or band, as such for example is produced by a carding engine, drawing frame, etc.

A stable band or sliver, according to the use of such term herein, denotes a non-twisted band or sliver consisting of individual fibers mutually adhesively interconnected by a setting adhesive.

Under the term web there is to be understood a fiber arrangement as such appears at the delivery side of a drafting arrangement.

It is known to the art to apply aqueous-oily emulsions to staple fibers, particularly to cotton, during a spinning process for the purpose, on the one hand, to reduce the accumulation of dust and fly during processing in the spinning mill and, on the other hand, to increase the sliding or gliding ability of the fibers among themselves in order to favor the subsequent drafting operation. Treatment of the fibers with such type preparations is generally referred to in the art under the generic term lubrication or oiling. In practice, application of the emulsion to the fibers is only undertaken during the first stage of a cotton spinning process, that is, in the blowing room. The products used for this purpose are quite varied. Nonetheless, such procedure in principal does not permit favorably affecting the technology of the spinning process itself, what is meant is shortening or simplification of the spinning process. Rather, even with the use of such additives the spinning process is strictly confined to conventional spinning processes, and the generally employed drafting techniques are not affected in any manner.

Furthermore, from the best fiber industry it is known to provide the fibers with water or weakly bonding substances-preferably with the plant glue dissolved in water 3,548,462 Patented Dec. 22, 1970 of the fibers themselves which are to be spunand thereafter to compact or consolidate such under high pressure between rolls. The plant or vegetable glue binding the bast cells together is softened in the thus obtained moist band, and these cells can then be easily displaced towards one another while being drafted.

In such type wet spinning processes of the hard fiber industry drying and regeneration of the adhesive force of the weakly bonding substances naturally must only take place after drafting, otherwise as the relevant practice has shown favorable drafting of the fibers is no longer rendered possible. In order to countreact against premature drying such weakly bonding substances are used, as mineral or animal greases. Thus, all of these substances only serve to enhance the gliding ability of the third fibers in order to ensure for spinning operations according to conventional techniques, as well as to simultaneously impart to the bands such as strength that they are capable of taking-up loads without attenuation or tearing to which they are subjected during deposition in sliver cans and during removal therefrom.

According to other proposals it is also known to apply so-called anti-glide agents to the fibers during the inning process for the purpose of building a rough film upon the surface of the individual fibers, which after twisting together the fibers at the end of the spinning process produces a better mutual, mechanical anchoring of the fibers and, therefore, should result in higher yarn strength. Due to the application of such substances to the fibers the previous spinning processes, however, remained completely unaffected.

With the practice existing up to the present it is known that it is not possible to draft staple fiber bands between two pairs of rolls or rollers higher than 4- to 6-fold without the use of special fiber guide means. While it is conceded that an increase of the drafts result with the use of special fiber guide means, such as slip rollers, small belts and so forth, in so doing, as is generally known, the drafting arrangements become considerably complicated and thus more liable to malfunctions.

Thus, a primary object of the present invention is to provide the prerequisites for a new drafting technique in which, notwithstanding the performance of higher drafts, it is possible to dispense with such additional fiber guide means.

A more specific object of this invention relates to an improved process for the preparation of a fiber arrangement or strand composed of staple fibers which can undergo a subsequent high drafting operation without the use of fiber guide means, as well as to a new and improved stable band produced according to the inventive process.

Another important object of this invention relates to an improved process for the preparation of a fiber arrangement composed of stable fibers in order to produce a new and improved stable band which is capable of being subjected to extremely high drafts on a drafting arrangement which is considerably simpler in physical structure, specifically is devoid of fiber guide means between the pair of feed rollers and pair of delivery rollers, and thus produces with great efliciency a web of improved quality.

Still a further very noteworthy object of this invention has reference to the production of a new and improved stable band which can be easily transported and generally handled without damage, can undergo extremely high drafts on much simpler drafting arrangements, and can produce yarns of superior quality and at greater efiiciency than heretofore possible.

At this point it is mentioned that the actual new and improved drafting process constitutes the subject matter of my co-pending, United States application, Ser. No.

430,320, filed Feb. 4, 1965, and entitled Process For Drafting Staple Fibers And Improved Web Produced According To Such Process, and reference may be readily made thereto. It should be appreciated that the present invention concerns itself with a process for preparing the new and improved fiber arrangement or strand used in the aforementioned inventive drafting process of my copending application.

The inventive process for preparing a fiber arrangement or strand composed of staple fibers in order to place such in a condition for undergoing a subsequent high draft resides in the features that, the aforesaid fiber arrangement is imbued with a liquid adhesive which sets after the fiber arrangement is consolidated or compacted at all sides and bonds the fibers among themselves into a stabilized band or silver, in short into a so-called stable band. Furthermore, if desired this fiber arrangement can be subjected to drafting directly prior to imbuing with the liquid adhesive. The soaked fiber arrangement advantageously has imparted to it a given cross-sectional configuration during compacting or consolidation at all sides, for example can be configured to be centrally symmetrical, such as quadrangular for instance. Concerning the liquid adhesive such can be applied in the form of an adhesive solution or an adhesive disperson. More specifically, the soaking operation advantageusly is performed with an excess of liquid which is again squeezed-out in a pressure zone. Squeezing-out of such liquid adhesive takes place until there remains a content of 20% to 80% of the fiber weight. The compression coming into effect in the pressure zone for the squeezing-out operation should be high. With the use of a pair of rollers the specific compression should amount to approximately 20 kg./cm. to 100 kg./cm. The fiber arrangement can be soaked with an adhesive material of low concentration and squeezed-out while retaining larger quantities of the liquid. On the other hand, with the use of an adhesive material of higher concentration it is also possible to squeeze-out While retaining smaller quantities of liquid.

Setting or hardening of the adhesive can take place in the presence of heat, for example by the introduction of heat of vaporization in order to evaporate the solvent or by polymerization or polycondensation, if desired, with the action of heat. If desired, soaking of the fiber arrangement or strand can take place by an adhesive which elastically bonds the fibers after setting. Preferably, there is employed an adhesive which has a small tendency to migrate during setting. The liquid to be introduced can also have added thereto, singly or in combination, compatible dyes, bleaching chemicals, sizing agents, defoamers, Wetting agents, fungicides and so forth.

The previously described preparatory-process is applicable for those process stages where there follows a high draft in the range of 30- to O-fold.

The stable band resulting from the previously described process essentially exhibits the following properties important for carrying out subsequent high drafting: In addition to stabilization in the lengthwise or longitudinal direction it possesses a transverse stabilization which imparts to the band a stable, centrally symmetrical form, for example rectangular or square. The inventive stable band can be considered to possess lengthwise or longitudinal stability if there appears minimum elongation of such band upon being subjected to a drafting force. Furthermore, the stable band can be considered to possess transverse stability if the band is stressed and the local appearing tensile forces are taken up as quickly as possible by the entire band and influence such as a unit. As will be explained in greater detail hereinafter the slope of the ascent of the force-elongation curve of the force-elongation diagram introduced as criterium for evaluating the lengthwise stabilization amounts to at least R ZS for tangent otC' -20, in other words, 25 times the slope of a similar, non-twisted, non-adhesively bonded spinning band having a value of tangent aC"=0.8. Additionally, the inventive stable band possesses a high density after the setting of the remaining liquid adhesive, which should be higher than 0.1 g./cm. Moreover, such possesses a high breaking length after setting of the remaining adhesive, preferably exceeding 500 meters. The adhesive content after setting (solid content) amounts to between 0.1% and approximately 4.8% of the fiber weight. Furthermore, the stable band possesses a high rigidity or bending strength which, while unimportant for drafting, in other respects is still advantageous.

The described stable band advantageously differs from conventional, non-twisted, carded or combed, also lubricated spinning bands possessing a breaking length of approximately 4-40 meters. These spinning bands which are neither lengthwise stabilized or transversely stabilized, at most possess a density which amounts to about 0.04 g./cm. a slope in the force-elongation diagram of tangent a=0.8, nor do they exhibit a rigidity worth mentioning. They do not possess, singly or in combination, any of the features of the stable band according to the invention.

The liquid adhesive suitable for the present inventive process after setting or hardening must exhibit a sufficient surface adherence (adhesion) with respect to the fibers and a sufficient cohesion. Suitable adhesive solutions coming under consideration for the purpose of the present invention are: starch and its derivatives, derivatives of cellulose, as for instance carboXymethyl-cellulose, cellulose-ether, etc., alginates, derivatives of albumines, synthetic resins, for instance melamine resins or formaldehyde, etc. Further, the adhesive can be employed in the form of an adhesive dispersion, as for example, a cellulose acetate. Depending upon the processing of a given type of fiber, for instance cotton, wool, man-made fibers or mixtures thereof, etc., a suitable selection is made among the adhesives in order to correspond to the above-mentioned features. Atthe same time of importance is, the small tendency to migrate before and during setting for the purpose of maintaining homogeneity, a suitable elasticity of the adhesive bond between the fibers after setting as well as good compatibility with other agents such as for example dyes, finishing and sizing agents, simultaneously to be applied with the adhesive to the fiber arrangement composed of staple fibers. In so doing, the elasticity of the adhesive bond can be accommodated to the existing conditions, in that for example agents which increase the elasticity of the adhesive bond are added to the adhesive in desired proportion. A certain elasticity is desired in order to prevent premature destruction of the transverse stability, for example by the feed rolls of the drafting arrangement. Also adhesive substances can be used, for instance the above-mentioned synthetic resins, by means of which it is possible to simultaneously produce a certain finishing effect. If, for example, mixtures of natural fibers and man-made fibers or mixtures of such among themselves should be processed, then it is possible to also use a combination of different adhesive substances accommodated to the individual components of the mixture.

The importance of the individual process steps directly responsible for the strength of the adhesive bond will be more fully explained hereinafter. The condensing or consolidation of the imbued fiber arrangement at all sides, among other things, serves to ensure that the structure of the band achieved in wet condition is also essentially maintained during the subsequent setting process in that the band actually remains in this condensed form. As a result, there is obtained the desired cross-sectional stabilization, the technological importance of which will be further considered shortly, Under the term cross-sectional stabilization or stability there is to be understood that the stable band retains its cross-sectional configuration up to the time it enters a drafting arrangement. In addition, it prevents opening of the band during transportation. The fiber arrangement or strand, if desired, can be subjected to drafting directly prior to soaking in order to transform the fibers into a straightened and as parallelized condition as possible. As a result, after adhesive bonding of the fibers there is obtained optimumconditions for carrying out a subsequent high draft. It will be appreciated the adhesive substance is introduced in excess, first, in order to be able to control and vary the quantity of adhesive solution remaining in the band by adjusting the pressure conditions during condensing or consolidation and, further, to expel as much as possible air imbedded in the fiber arrangement and to achieve a homogeneous liquid distribution.

It will be recalled, in order to introduce a certain required solid content of adhesive material into the fiber arrangement in one extreme case such can take place with smaller concentrations of adhesive solution and larger quantity, or, in the other extreme case, with larger concentrations and smaller quantity. It has been found that optimum conditions result, for example for cotton, if the quantity of liquid adhesive remaining in the band after condensing and squeezing-out does not fall below a certain lower limit of approximately 20%, based upon the weight of the cotton. On the other hand, approximately 80% should not be exceeded since then, depending upon the conditions of drying, the factors which are of decisive importance for drafting could be negatively influenced. Within the above-indicated range there additionally exists an approximately considerable proportionality between the introduced solid content and the achieved breaking length. If too little or an insuflicient bonding adhesive is introduced into the fiber arrangement then such again opens before and during setting, notwithstanding condensing into a small cross-section in wet condition. There results a puffed-up or fiuffy structure, which is neither transversely or lengthwise stabilized, possessing small breaking length and small density. In other words, there exists a structure possessing quite unfavorable properties for undergoing subsequent high draft. The high specific compressions coming into play during squeezing-out in the pressure zone also thereby serve for dosing the previously described favorable content of adhesive substance per weight of fiber material.

The importance of the above-mentioned properties of the stable band produced according to the inventive process will be further explained hereinafter:

It is known that the average drafting force exerted upon a spinning band located in a drafting zone is not constant, rather varies because of inhomogeneities. During drafting the spinning band correspondingly elongates more or less strongly and, in so doing, is capable of bringing about drafting disturbances. Consequently, there appear the known and feared drafting waves. This tendency towards drafting waves is markedly reduced by the mentioned lengthwise stabilization and the improvement of the forceelongation relationship of the stable band prepared according to the invention. Moreover, there results yarn quality values, while dispensing with mechanical fiber guide means in the high drafting zone, which are scarcely attainable according to conventional spinning processes.

The mentioned lengthwise stabilization provides the further advantage that staple fibers can be drafted with drafting zone lengths which lie considerably above the length of the longest fibers, even without mechanical fiber guide means. Thus, there are provided the prerequisites necessary for processing fibers of different staple lengths upon one and the same drafting arrangement. It should be appreciated that such constitutes one of the more important advantages of the invention.

The transverse stability is likewise of decisive importance for carrying out the subsequent high draft. Firstly because the favorable cross-sectional form is considerably maintained during the drafting operation. Additionally, the forces effective Within the cross-section resulting from individual fibers being subjected to the drafting force, are transmitted as quick as possible via the transverse bond to the stable band as a unit. Hence, the tensile forces which appear do not propagate themselves directly backwards, rather are taken over by the entire structure of the total stable band. As a result, there exists ideal conditions for faultless high drafting.

The high density is of importance insofar as it permits as large as possible fiber mass in the smallest cross-section to be delivered to a drafting arrangement, thereby resulting in larger drafts without endangering the twistingin of the marginal fibers.

The breaking length is a measure for the mutual strong bond of the fibers and can be very easily determined by measurements. Thus, in many practical cases the magnitude of the breaking length should be snfiicient as a criterium for judging the behavior of a stable band subjected to a high draft.

The achieved high rigidity or bending strength is of greater importance insofar as it permits automatic infeed and passage of the stable bands through the drafting arrangement.

It has also proven to be of advantage to use the new drafting techniques described for high drafts in preliminary stages of a spinning process in order to further improve the yarn in compatibility with the already considered end or terminal stage.

In the preliminary stages there exists the need to compensate the irregularities appearing at the fiber bands by doubling without undertaking an extreme attenuation. Depending upon the doubling count the drafts thus vary between 4- and approximately 15-fold.

In order to technologically improve the preparatory drafting operation also in this low drafting range drafting is undertaken with a compact doubled fiber arrangement consisting of a number of stable bands produced in a preliminary stage. Once again, the degree of bonding can be expressed by the corresponding breaking length, the density and by the cross-sectional stabilization and the lengthwise stabilization of the individual stable bands.

In the first instance, the breaking length and the lengthwise stability of the individual stable bands are decisive for the quality of the draft. Since percentually a relatively large fiber mass is withdrawn through the pair of delivery rollers of the drafting arrangement during small drafts the average drafting force should not be too high, and, thus, there should be employed a and a breaking length greater than 200 meters, in other words, values which generally lie beneath those given for high drafts. Naturally, breaking length and R can considerably vary above the given limits depending upon the adhesive material, staple length, and so forth.

The physical effects resulting during drafting from the setting bond and the lengthwise stabilization are described in detail in my previously mentioned, co-pending United States application, Ser. No. 430,320.

The simultaneously achieved relatively high density of approximately 0.05 g./cm. and more and the therewith associated cross-sectional stabilization of the individual stable bands permits the formation of a compact, uniform, doubled fiber arrangement or strand, such likewise favorably affecting the drafting process.

Since the introduction of a liquid adhesive in the preparatory process stage already represents a wet treatment it is meaningful to introduce into the fiber arrangement at this stage further application agents. Thus, it is possible to dye, to bleach or otherwise treat the stable band by means of additives, such as dyes, bleaching chemicals, finishing agents and so forth. Such liquids can also 'be introduced at temperatures greater than room temperatures. What is required is that there exists a compatability of the commingled components, and at the same time that the conditions required according to the invention for the bonding of the fibers are met.

Such type impregnated individual stable bands can be subjected to the action of heat prior to setting or harden- 7 ing of the adhesive substance, or setting can coincide with heat treatment, for example in the case of polymerizing adhesive substances.

The individual set stable bands, according to the spinning plan, are thereafter delivered in appropriate doubled fiber arrangement to a drafting arrangement for drafting. In spite of relatively small drafts there appears a readily perceivable homogeneous, highly parallelized web to which no fiber bunches or concentrations adhere, and which clearly demonstrates'the extreme effectiveness of drafting with individual bands prepared according to the teachings of the present invention.

The effect of the executed doubling is manifold. First of all, there is achieved the known compensation of the irregularities associated with the individual stable bands. Furthermore, by virtue of the extremely good separation of the stable bands there occurs a mixing effect which has an equalizing effect with regard to the raw material as well as also for instance, for the undertaken dyeing. Naturally, in this instance different colors can also be mixed, as such for instance occurs with blends. Also the distribution of the already set adhensive substance is further improved, this being of importance for reactivatable adhesive substances in the subsequent adhesive stage.

The more uniform web is then subjected to further soaking immediately after delivery from the drafting arrangement, and as a result of the initially described process stage there finaly appears the stable band destined to undergo a high draft.

Generaly speaking, it can be stated that by virtue of the described process it is possible to provide within the band itself, in the simplest manner, the fiber control desired for subsequent drafting, in a manner corresponding to requirements, that is, in lieu of the static friction of the fibers among themselves brought about by the material there occurs a controllable bond.

As explained in greater detail in my aforementioned Unied States application, Ser. No. 430,320, the adhesive bond between the staple fibers is such that it will yield or rupture before destruction of the individual fibers.

Other features, objects and advantages of the present invention will become apparent by reference to the following detailed description and drawing in which:

FIG. 1 schematically illustrates an embodiment of apparatus for carrying-out the inventive process;

FIG. 2 illustrates in cross-section a detail of the arrangement of FIG. 1, taken along the line IIII thereof;

FIG. 3 is a cross-sectional view taken along line III- III of FIG. 1, yet omitting the coresopnding rolls for clarity of illustration;

PG. 4 is a cross-sectional view taken along the line IV-IV of FIG. 1;

FIG. 5 is a cros-sectional view taken along the line V-V of FIG. 1;

FIG. 6 is a cross-sectional view taken along the line VIVI of FIG. 1; and

FIG. 7 is a force-elongation diagram for different staple fiber bands.

Describing now the drawing, it will be seen that a suitable prepared fiber arrangement or strand V is subjected to drafting between a pair of rolls or rollers 2 and 3 and by means of the roller 4 is delivered to a so-called rolling-in element or body 5. The later transforms the web 1 (FIG. 3) arranged in one plane through the shapes 1 and 1 (FIGS. 4 and 5 respectively) gradually into a ring-shaped or annular cross-section 1 (FIG. 6). At the beginning of the rolling-in operation, directly after departure from the delivery rollers 3 of the drafting arrangement, the web 1 preferably possesses a rectangular cross-sectional configuration. Due to the action of the rolling-in body 5 the fiber layer 1' is already pre-shaped to posses a slightly concave form in the sectional plane depicted in FIG. 4, whereas in FIG. 6 the annular crosssectional shape of the layer 1" is already imparted. The lower end of the rolling-in body 5 is surrounded by the layer 1' and externally bounded by a feed or inlet nozzle 6. A liquid delivery conduit or line 7 enters the forward portion of the rolling-in body 5 at its region which is still free of fibers and again emerges from such rolling-in body 5 at the bottom in the form of an extension 8. The staple fibers in this cross-section and also thereafter to a certain extent form a close filter tube (FIG. 6) through which liquid under pressure can be pressed through the mentioned staple fiber-filter tube via the conduit 7. In so doing, at the lower end 6a of the feed nozzle 6 the staple fibers find a peripheral counter-support operable to prevent the staple fiber tube from becoming torn apart by the built-up liquid presure. The details of the physical structure of the liquid applying device do not constitute a part of the subject invention, yet a device suitable for this purpose is described and claimed in my co-pending United States application, Ser. No. 326,058, filed Nov. 26, 1963 and entitled Method and apparatus for the Continuous Introduction of Liquid Into a Staple Fiber Band or the Like.

By means of such a liquid applying device it is possible to displace the air imbedded in the fiber layer from the center radially outwards and to homogeneously and in excess soak the staple fiber layer with liquid. In a directly subsequent pressure zone within the length of the staple fibers, this pressure zone being formed by mutually pressing together two disks 9 and 10 which are lateraly covered by two cover plates 11 and 12 (FIG. 2), excess liquid is expelled and squeezed-out under relatively high specific pressure and the staple fiber arrangement is compressed into a compact band 13 of high density.

The disks 9 and 10 can advantageously be provided at their periphery with rubber rims or crowns 15 in order to improve sealing of the pressure zone. By means of suitable recesses 11' and 12 provided at both cover plates 11 and 12 it is ensured that excess liquid can laterally fiow away above the pressure zone. Such collects in the collecting troughs or reservoirs 14 in order, if desired, to again be supplied via the conduit 7 of the liquid applying device by means of suitable non-illustrated mechanism. The resulting stabilized, so-called stable band after setting thereof, for example through drying by means of a heating coil 16, is delivered to a Single zone-drafting arrangement of a ring spinning frame (not illustrated) which does not possess any fiber guide means.

Since the force-elongation relationship is particularly suited for quantitatively determining the lengthwise stabilization of a stable band, such will be more comprehensively considered in conjunction with FIG. 7.

A stable band prepared by a setting bond exhibits a characteristic force-elongation relationship as depicted in FIG. 7 by the curve a, for instance for a cotton material. An apparent proportionality exists between the force P and the elongation e from the time of application of load till rupture of the band. In other words, the stable band approximately ideally follows Hooks law. The slope of the ascent of the curve a is of particular interest since this slope represents a measure for the required lengthwise or longitudinal stabilization of the stable band. The steeper the ascent the better the lengthwise stabilization, that is, the less does the stable band elongate with a given tensile load.

At this point it is mentioned that as a practical matter the force-elongation curve of a material does not generally conform to a straight line nor does it have a substantial portion of its curve linear. Thus, if for a given material a considerable portion of its force-elongation curve is not linear, particularly from the point of intersection with the axes so that it is not readily possible to ascertain a value of the tangent to such curve characteristic for the slope of such curve, then it is necessary to replace such curve by a straight line which approximates the aforesaid curve. In order to further explain such, let it be assumed that a given material possesses a force-elongation curve typical of curve 0 of FIG. 7. It will be appreciated that in the case of this more complicated form of curve c it is not possible to obtain a characteristic value of the slope of such curve since such slope continuously varies along the surface of the curve. Now when this happens, then it is necessary to replace the curve by a straight line g which approximates the curve 0 so that from such straight line g it is possible to define the slope in terms of tangent a, in this case tangent PA a= Thus, tangent a can be very easily employed as comparison value for judging the lengthwise stability of difierent types of staple fiber bands. Hence, by way of example, tangent at of the curve a is large for a strongly bonded, in other words, lengthwise stabilized band, whereas for the dotted line curve a of less steepness and corresponding to a similar, yet less strongly adhesively bonded stable band, tangent a' now only amounts to approximately half of that of curve a. As previously explained the curve 0 is only introduced as a definition aid, whereas the curve b with a steepness of a" corresponds to the force-elongation behavior of a similar, that is of the same cotton material, yet non-twisted, non-bonded spinning band. It will, therefore, be readily appreciated that due to the smaller slope, tangent a" is much smaller than tangent a and tangent a of the strongly and less strongly bonded stable bands, respectively. The slope relation for a stable band prepared for high drafts amounts by way of example to:

slope of a bonded stable band tan a slope of a non-bonded spinning band tan a R is greater than for a stable band prepared for drafting in the preparatory stage. Naturally, as a pre-condition the scale of the force -P and the elongation e for all fiber bands to be compared with one another is the same. The importance of the force-elongation relationship just discussed has also been explained in detail in my mentioned co-pending United States application, entitled Process for Drafting Staple Fibers and Improved Web Produced According to Such Process.

Furthermore, it is remarkable that the elongation at breakage of bonded stable bands, which naturally is dependent upon the type of fiber as well as the manner of bonding, is exceedingly small. Depending upon band thickness and so forth, it only amounts to approximately 1.5% to 1.8% with cotton for instance.

EXAMPLE 1 A carded cotton of American origin with a 1 /16" staple suitably prepared in a preparatory stage with 6- fold doubling and with a weight of the individual bands of 2370 tex is drafted with a 6-fold draft. Such is then imbued with liquid adhesive introduced in excess by means of the liquid delivery or applying device of FIG. 1 arranged directly at the delivery rollers.

The subsequently arranged disks 9 and 10 provided with a rubber rim and between which there is formed the pressure zone possess a width of two millimeters. With a load of 9 kilograms (45 kg./cm. specific compression or pressure) and by employing an adhesive solutioncontaining 200 grams Vibatex S per liter of solutionthere is obtained at the discharge end a band 13 Which contains 44% liquid adhesive based upon the weight of the raw material. Under the term weight of the raw material there is to be understood the Weight of the cotton at a temperature of approximately C. and a relative humidity of approximately 65%.

Delivery of the still wet band 13 takes place at a velocity of about 100 meters per minute. After drying, that is, setting to a stable band at room temperature such exhibits a breaking length of 1454 meters and a density of 0.176 g./cm. The breaking length is determined at a so-called Baers yarn tester (system Schopper) operating with a span length of 500 millimeters. The introduced solid 10 content, that is, the quantity of introduced solid adhesive substance after setting amounted to 1.76% based upon the raw weight of the cotton. The slope amounted to tangent o=l 13 in contrast with tangent a"=0.49 of an analogous non-bonded spinning band, so that R=230.

The bonded or set stable band is thereafter subjected to a 64-fold draft upon a single zone-ring spinning drafting arrangement, so that there is produced at the delivery side a yarn of 37 tex. Between the pairs of feed rolls and delivery rolls of the drafting arrangement no special fiber guide means were used. The yarn produced in this manner is of exceptional uniformity and exhibits an unevenness percent or linear irregularity of up to 8.7% measured upon the Uster -Evenness Tester, corresponding to an index value of I: 1.61 (Uster-standard). According to the usual quality evaluation an index value of I=2.3 is already considered as uniform. The yarn possesses a very fine and smooth appearance which is approximately like that of a combed yarn.

Certain modifications of polyvinyl alcohols have proven themselves as especially suitable adhesive materials for preparing cotton for a subsequent high draft. According to Example 1 the product Vibatex S which can be obtained from The Ciba Company, Basel, Switzerland, has been given as one such suitable type of adhesive substance. Depending upon the subsequent degree of drafting, by way of example for cotton such can be introduced into the band in concentrations of 150-300 grams Vibatex S per liter solution and in a quantity of 20% to of the weight of the cotton.

After drying has been completed there can be obtained breaking lengths of the stable band in non-twisted condition of approximately 800-4000 meters. In the extreme case, the breaking length can in fact exceed 4000 meters. Of course, the exact value of the breaking length is dependent upon, the type of cotton employed and its staple, the content of fiber wax, the fineness of the fiber, from the number of the stable band and so forth. For instance, in order to elucidate the dependency upon the staple length it is pointed out that, for example, with a short staple cotton species (flat strip) and a certain irnpergnation with adhesive material a breaking length of 1100 meters was measured after setting, whereas a normal American cotton of 1 /16" staple under the same conditions of adhesive bonding resulted in a breaking length of 1840 meters. A selected fine American cotton of 1 /16" staple under the same conditions reached just quite 2250 meters.

The introduced solid content of Vibatex S after setting and within the given limits of concentration and quantity amounted to 0.6% to 4.8% of the weight of the raw cotton. In so doing, there is to be observed that the portion of solids of Vibatex S amounts to 20% in the form commercially available on the market.

EXAMPLE 2 The same cotton according to Example 1 likewise with a feed count of 2370 tex is doubled 6-fold, however drafted with a 12.5-fold draft and soaked with an adhesive solution containing 300 grams Vibatex S per liter solution. Another band is provided with 250 grams Vibatex S per liter solution. The delivered bands exhibit a band weight of 1140 tex. At the disks 9 and 10 (width 1.5 millimeters) provided with a rubber rim there is worked with a load of 6 kilograms (4O kg./cm.), corresponding to a take-up of 59% moisture at the discharging band 13 in the case of the higher concentration, and a take-up of 52% moisture in the case of the lower concentration of 250 grams per liter. Corresponding to the larger quantity of introduced adhesive material (portion of solids 3.54%) the breaking length after setting of the cotton band with the higher concentration amounted to 3494 meters, with the lower concentration (portion of solids 2.6%) 2835 meters. In both cases the density is practically identical and amounts to 0.3 g./cm. notwithstanding dilferent quantities of adhesive. For the stronger 1 1 bond tangent a, amounts to 129, for the weaker 108, whereby again with a tangent c" of the compared nontwisted spinning band of 0.49 there resulted a value of R=264 and R=220, respectively. The delivery speed in both cases amounted to 100 meters per minute.

Again, drafting subsequently occurred upon a single zone-drafting arrangement of the ring spinning frame. Once again, there was likewise worked under the conditions of a free draft, that is, without particular fiber guide means present in the drafting zone. An extremely high draft of 1l5-fold was used, whereby after suitably imparting twist there was obtained a yarn of 9.9 tex. Although, the minimum acceptable number of fibers per yarn cross-section was already exceeded for the here selected species or assortment, the yarn exhibited a linear irregularity of 12.4% when the members of the drafting arrangement worked correspondingly accurate and in the case of strong bonding of the stable band. This represents an extreme peak value. The irregularity drops to 13.9% for the weaker bond. The direct dependency between the strength of the bond and the attainable yarn uniformity is markedly noticeable. In so doing, the yarn quality becomes a controllable value and can, as desired, be accommodated to requirements.

EXAMPLE 3 In contrast to Examples 1 and 2, in this case there is processed a regenerated, lustrous cellulose fiber with a cut of 40 millimeters, a fineness of 1.5 den as well as a feed count of 2370 tex which is likewise doubled 6-fold and attenuated with a 12.7-fold draft. 200 grams Vibatex S per liter solution is introduced as the liquid adhesive material. However, this time the disks 9 and 10 are formed of steel (width 1.5 millimeters) and are pressed against one another with a load of 12 kilograms (80 kg./cm. specific compression). In contrast to Examples 1 and 2, in this case there is a take-up of 21% moisture at the discharging band 13, corresponding to a portion of solid content of only 0.84%.

After setting or hardening of the adhesivein comparison with cottonthere results a considerably larger breaking length of 8000 meters with a density of 0.41 g./cm. Thus, there can be observed that in spite of smaller content of solids corresponding to the character of the fiber there is achieved an extremely high breaking length and depending upon the employed raw material the range of breaking lengths can considerably differ, and without going outside of the farmework of the invention.

Further processing again takes place at a single zonedrafting arrangement of a ring spinning frame without the use of particular fiber guide means in the drafting zone. With a sufficiently high draft a useful yarn can be produced notwithstanding the extremely high breaking length.

EXAMPLE 4 A carded cotton of American origin with a 1 /16" staple in the form of a card sliver of 4220 tex is doubled 2-fold and drafted in a drafting arrangement with a 4.28- fold draft, whereby there results a delivery count of 1970 tex. A combined liquid is introduced into the liquid applying device which essentially consists of 40 grams Vibatex S" per liter solution with an added reactive dye, an appropriate catalyst and further additives in order to be able to simultaneously undertake dyeing in addition to bonding. The liquid is pressed-out between the subsequently arranged disks 9 and 10 equipped with a rubber rim, again possessing a Width of 2 millimeters, under a load of 3 kilograms until 58% of the raw weight in liquid adhesive still remains.

After fixation of the dye by the so-called cold padbatch fixation method known in the dyeing art and subsequent setting, the stable bands produced according to this process exhibit a breaking length of 243 meters at 12 a density of 0.14 g./cm. a slope of tangent a=14, so that with tangent a=0.49, R=29.

The degree of bonding in this dyeing stage is dependent upon the objective sought, to obtain with subsequent drafting a web of the best possible homogeneity, that is, namely, without any kind of formation of fiber bunches or agglomerations and best possible separation. It should be evident that the foregoing is dependent upon the type of drafting arrangement employed as well as its adjustment. However, as a general rule the breaking length of the stable bands should not drop below 200 meters, and the slope of tangent a should not be less than 4. R=8 when tangent a"=0.49. With a still readily possible value of tangent a=0.8 then, for instance, R:5.

After dye fixation and drying the dyed individual stable bands of 1970 tex are further processed by doubling 6-fold and 6-fold drafting. In so doing, a liquid adhesive comprising 200 grams Vibatex S per liter solution is introduced into the band or sliver by means of the liquid delivery device. Between the subsequent arranged disks 9 and 10 having a width of two millimeters and again provided with a rubber rim there is employed a pressure of 9 kilograms. The departing band 13 then still contains 46% of the cotton weight in liquid adhesive, corresponding to a solid content of 1.84%. The introduction of liquid takes place at a throughpassage velocity of meters per minute. After drying and setting to stable bands there results a breaking length of 971 meters with a density of 0.20 g./cm. Then these bands are subjected to a high draft of 53-fold at a ring spinning-drafting arrangement.

It is also further possible to provide different kinds of adhesive materials for the subsequent bonding stages. Thus, with cotton for example it is possible to successfully use in the dyeing stage a carboxymethyl-cellulose, whereas in the subsequent stage then, by way of example, Vibatex S is used. However, in each case there must be guaranteed for the chemical tolerance of the substances, in other words, they must be compatible. It is also conceivable that, for instance, the liquid dye itself exhibits sufficient adhesive strength in order to attain the desired strength of the bond at the preliminary stage.

Dyed yarns produced according to the inventive preparatory process not only manifest themselves through their exceptional uniformity and smooth and clean appearance, rather they additionally possess an extremely good dye homogeneity. Consequently, there is automatically eliminated a number of difliculties of the typically employed yarn dyeing processes.

While there is shown and described present preferred embodiments of the invention it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practised within the scope of the following claims.

What is claimed is:

1. In a spinning process for the production of yarns, the process for the preparation of a fiber arrangement of staple fibers for undergoing a subsequent draft comprising the steps of: moving a strand-like fiber arrangement to a liquid adhesive applying means, then subsequently imbuing said strand-like fiber arrangement with a liquid adhesive, condensing the fiber arrangement at all sides, the liquid adhesive setting after the aforesaid condensing of the fiber arrangement in order to bond the staple fiber thereof into a stable band capable of undergoing a subsequent draft in a drafting arrangement of a spinning machine such that the bond between the staple fibers will yield before destruction of the individual fibers.

2. The process for the preparation of a fiber arrangement of staple fibers for undergoing a subsequent draft according to claim 1 including the step of subjecting the fiber arrangement to drafting directly prior to imbuing with liquid adhesive.

3. The process for the preparation of a fiber arrangement of staple fibers for undergoing a subsequent draft 13 according to claim 2 wherein drafting is undertaken at a compact uniform doubled fiber arrangement incorporating a number of stable bands produced in a preliminary stage.

4. The process for the preparation of a fiber arrangement of staple fibers for undergoing a subsequent draft according to claim 3 wherein the stable bands produced in the preliminary stage are squeezed-out until they contain a liquid content of approximately 40% to 80% of the weight of the fibers.

5. The process for the preparation of a fiber arrangement of staple fibers for undergoing a subsequent draft according to claim 1 wherein the steps of condensing at all sides and setting of the liquid adhesive is carried out to impart lengthwise stability to the fiber arrangement.

6. The process for the preparation of a fiber arrangement of staple fibers for undergoing a subsequent draft according to claim 1 wherein the steps of condensing at all sides and setting of the liquid adhesive is carried out to impart transverse stability to the fiber arrangement.

7. The process for the preparation of a fiber arrangement of staple fibers for undergoing a subsequent draft according to claim 1 including the steps of imparting a definite cross-sectional form to said fiber arrangement during condensing.

8. The process for the preparation of a fiber arrangement of staple fibers for undergoing a subsequent draft according to claim 7 wherein said fiber arrangement has imparted to it a central symmetrical cross-sectional form.

9. The process for the preparation of a fiber arrangement of staple fibers for undergoing a subsequent draft according to claim 8 wherein said central symmetrical form is substantially rectangular.

10. The process for the preparation of a fiber arrangement of staple fibers for undergoing a subsequent draft according to claim 8 wherein said central symmetrical form is substantially quadrangular.

11. The process for the preparation of a fiber arrangement of staple fibers for undergoing a subsequent draft according to claim 1 wherein said liquid adhesive is applied to said fiber arrangement in the form of an adhesive solution.

12. The process for the preparation of a fiber arrangement of staple fibers for undergoing a subsequent draft according to claim 1 including the steps of imbuing the fiber arrangement with a liquid adhesive containing smaller concentration of adhesive material, and subjecting said fiber arrangement to a squeezing operation while retaining larger quantities of liquid.

13. The process for the preparation of a fiber arrangement of staple fibers for undergoing a subsequent draft according to claim 1 including the steps of imbuing the fiber arrangement with a liquid adhesive containing larger concentration of adhesive material, and subjecting said fiber arrangement to a squeezing operation while retaining smaller quantities of liquid.

14. The process for the preparation of a fiber arrangement of staple fibers for undergoing a subsequent draft according to claim 1 wherein setting of the liquid adhesive takes place by polymerization of the liquid adhesive.

15. The process for the preparation of a fiber arrangement of staple fibers for undergoing a subsequent draft according to claim 1 wherein setting of the liquid adhesive takes place by polycondensation of the liquid adhesive.

16. The process for the preparation of a fiber arrangement of staple fibers for undergoing a subsequent draft according to claim 11 wherein setting of the liquid adhesive takes place by evaporation of its solvent.

17. The process for the preparation of a fiber arrangement of staple fibers for undergoing a subsequent draft according to claim 1 including the step of simultaneously adding to the liquid adhesive at least one compatible finishing agent selected from the group comprising dyes, bleaching chemicals, wetting agents, defoamers and fungi cides.

18. The process for the preparation of a fiber arrangement of staple fibers for undergoing a subsequent draft according to claim 1 wherein said liquid adhesive is applied to said fiber arrangement in the form of an adhesive dispersion.

19. The process for the preparation of a fiber arrangement of staple fibers for undergoing a subsequent draft according to claim 1 wherein said fiber arrangement is imbued With an excess of liquid adhesive.

20. The process for the preparation of a fiber arrangement of staple fibers for undergoing a subsequent draft according to claim 19 wherein the excess liquid adhesive is squeezed-out until there remains a content of 20% to of the weight of the fibers by the employment of a high specific compression in a pressure zone.

21. The process for the preparation of a fiber arrangement of staple fibers for undergoing a subsequent draft according to claim 20 wherein a specific compression of approximately 20 kg./cm. to kg./cm. is employed in the pressure zone.

22. The process for the preparation of a fiber arrangement of staple fibers for undergoing a subsequent draft according to claim 1 including the step of applying heat to effectuate setting of the liquid.

23. The process for the preparation of a fiber arrangement of staple fibers for undergoing a subsequent draft according to claim 1 in cluding the step of imbuing the fiber arrangement with an adhesive material which after setting elastically bonds the staple fibers.

24. The process for the preparation of a fiber arrangement of staple fibers for undergoing a subsequent draft according to claim 1 wherein the fiber arrangement is imbued with a liquid adhesive having as small as possible tendency towards migration during setting.

US. Cl. X.R. 161-177; 57l64

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