NO841416L - POLYAMIDE FILAMENTS AND PROCEDURES IN PREPARING THEREOF - Google Patents

Description

This invention relates to novel conjugated filaments and

a new method for the production of conjugated filaments. In particular, the invention relates to new conjugated polyamide filaments with a high degree of ripple at "high load" and a new method for producing such filaments.

With the expression "ripple at high load" is meant here ripple (e.g. spirals) which has been developed and/or maintained during the performance of the ripple test defined below at high load. The expression "ripple at light load" means ripple developed and/or maintained during the execution of the ripple test defined below at light load.

Conjugated filaments and their preparation are well known

In the subject. In typical cases, the manufacturing process comprises two completely separate and discontinuous operations: a melt spinning operation where two different polymers are coextruded to form "prespun" filaments which are wound onto a spool to form a layup unit, and a drawing operation where the "prespun" filaments are pulled off the spool , stretched and then wound onto a second spool for on

new to form a planning unit. The polymers may differ from each

others with regard to e.g. chemical structure (see, for example, US Patent No. 4,019,311), or the polymers may have the same structure and be different as a result of having different relative viscosities (see, for example, US Patent No. 3,536,802) or because one of the polymers contains an additive that changes its nature, while the other of the polymers does not contain any such additive (see, for example, US Patent No. 4,271,233). US Patent Nos. 4,244,907 and 4,202,854 describe a method for producing conjugated filaments, whereby instead of coextruding two polymers, a single polymer is extruded to form a molten monocomponent stream which is treated, e.g. in that it is subjected to cooling on one side before it is completely solidified (see, for example, US patent document no. 4,244,907) or is heated on one side immediately after it has solidified (see, for example, US patent document no. 4,202,854). In these cases, the filament is stretched immediately after the treatment on it

one side of the filament.

Conjugated filaments which have been produced by methods known in the art usually lack the ability to develop crimping properties of the type required of filaments used in the manufacture of articles of clothing which are to exhibit "stretch", such as socks, stockings, tights, sportswear, leotards, etc. For this reason, most filaments that have been used commercially to make garments with stretch properties have been nylon 66 or nylon 6 monocomponent filaments that have been mechanically pseudo-textured. Although the conjugated polyamide filaments described in US Patent Nos. 3,399,108 and 3,418,199 have the ability to develop a suitable crimp with properties of the type required for use in stretch garments, the filaments are deficient in other respects, compared with the fake textured nylon monocomponent filaments. For example, the monocomponent filaments exhibit lower shrinkage values in boiling water and therefore provide better dimensional stability to garments such as stockings, where the ripple develops after knitting. Similarly, the ripple of the monocomponent filaments can develop in the dye bath during conventional • dyeing operations where garments are dyed (e.g. in boiling water at atmospheric pressure), while the ripple of these conjugated filaments requires special treatment, namely treatment with superheated steam (118°C).

The present invention relates to a new method for producing conjugated filaments and new conjugated filaments. More specifically, the invention provides a simple and economical method for producing conjugated filaments with improved properties, such as ripple properties. In particular, the invention provides conjugated polyamide filaments with the curling properties under heavy load and the shrinking properties in boiling water that are required for use in garments that must have stretch properties, and especially for use in women's stockings. The invention also provides a method for producing such polyamide filaments.

According to one aspect of the invention, the method comprises stretching a fresh filament at a stretch ratio higher than 1.0 and lower than that which would cause breakage of the filament, which filament has been melt-spun at a spinning speed of at least 1829 m per minute and comprises a first longitudinal polymer segment and a second longitudinal polymeric segment which are arranged eccentrically along the longitudinal axis of the filament and deviate from each other with regard to dimensional change characteristics, the latter deviation and the said stretch ratio being chosen so as to provide a filament with a test value in the ripple test at a low load of at least 12%, preferably at least 20%. By the term "fresh" filament is meant a filament which has not been allowed to age under such conditions that, when stretched, it is not significantly improved compared to the properties obtained when a filament spun under the same conditions is aged for 4 hours at 70% relative humidity and at a temperature of 25°C before stretching to the same stretch ratio. The properties of fresh filaments can in some cases be retained at least temporarily by the filament being collected and kept under water-free conditions until they have been stretched, as shown e.g. in example 12 below. Although the inventors do not wish to limit themselves to particular theories, it is believed that the use of a fresh filament leads to desirable results due to the crystalline properties at the time of stretching.

Preferably, the method is a spinning-stretching process where the stretching of the filament is carried out during the manufacturing process itself during melt spinning, after the filament has been formed and before it has been wound up.

According to a preferred embodiment of the invention, the spinning-stretching process comprises the coextrusion of two molten, fiber-forming polymers with different final velocity distances to form a molten stream in which the polymers are arranged eccentrically in relation to the longitudinal axis of the stream, cooling and solidification of the molten strand in a cooling zone to form a filament (solidified molten stream), attenuation and acceleration of the molten stream by withdrawing the filament from the cooling zone at a speed (ie spinning speed) of at least 1829 m per minute and. subsequent stretching of the filament at a draw ratio higher than 1.0 in the production line before the filament is collected and, preferably, as soon as possible after the molten stream has solidified, the process agents and polymers being selected so as to obtain a filament with a test value in the ripple test at light load of at least 12%, preferably 20%. Preferably, at least one of the polymers is a polyamide and most preferably nylon 66. As the term is used here, "solidified" means that

the molten stream has cooled sufficiently that it no longer leads to (ie fuses with) other filaments or yarn guide surfaces. Polymers with "different final speed distance" are characteristic in that, under the special spinning-stretching conditions used to form the molten stream, they solidify at different distances from the extrusion point (ie at different distances from the spinning die). The measurement of final velocity distances will be described later.

According to the most preferred embodiment of the spinning-stretching process, both polymers are polyamides, and the process conditions and the polyamides are chosen so that a conjugated filament is obtained with a measurement value in the crimp test at high load of at least 12% and such a measurement value in the shrinkage test in boiling water that the quotient obtained by dividing the measurement value in the ripple test by the measurement value in the shrinkage test in boiling water of at least 1.0. This quotient will be referred to here as the "crease/shrink ratio". Generally, the highest measurement values are obtained in the ripple test at high load and the lowest measurement values in the shrinkage test in boiling water when highly crystalline homopolyamides are chosen, such as nylon 66 and, to a lesser extent, nylon 6. Preferably, both homopolyamides have the same chemical structure, i.e. they consist of recurring structural units with the same chemical formula. Preferably, each of the polyamides is a nylon 66.

The conjugated filaments produced according to the method according to the invention exhibit no or only a small torque (i.e. are essentially free of torque), and they therefore exhibit certain advantages over false-textured filaments which exhibit a significant torque. An advantage is that the conjugated filaments can be used in the form of medium denier single yarn (e.g. a 140 denier/34 filament yarn), while friction fake twisted filaments cannot usually be used in this form due to the twisting moment, but rather are used in the form of a twisted yarn where two 70 denier single yarns with opposite twist are twisted to form a 140 denier yarn with balanced twist.

The crimp test at high load (which is defined below) is used here to determine the applicability of conjugated filaments for the production of hosiery and other garments that must exhibit tensile properties. The higher the measured value in the ripple test at high load, the more suitable the filament is for use in garments with stretch properties. For hosiery, the measured value should be at least 12%, preferably at least 15%. Although in practice the stocking is usually placed in a dye bath which is kept at room temperature or at a temperature close to room temperature, and the temperature of the bath is then raised to the boiling point in order to simultaneously develop frizz and dye the stocking, the ripple test at high load is much faster and easier to use than the ripple test carried out in boiling water. The ripple test at high load correlates very well with the ripple test in boiling water for filaments made from homopolyamides with the same chemical structure but with different final velocity distances. Filament yarn according to the invention has been used for stretching women's stockings and has developed excellent crimp properties and has shown satisfactory shrinkage properties in boiling water when the stocking has been placed without obstruction in a dye bath.

Fig. 1 schematically shows an equipment that can be used for carrying out the spinning-stretching process according to the invention,

and fig. 2 shows the cross-section of a conjugated filament produced by the spinning-stretching process according to the invention.

The method according to the invention provides conjugated filaments with improved properties. For example, the method according to the invention can be used for the production of conjugated polyamide filaments which are particularly useful for the production of women's stockings. Although the method according to the invention can also be used for the production of a conjugated filament composed of three or more fiber-forming polymeric segments, the two-segment filament is preferred, because it offers economic advantages over other multi-segment filaments. As the number of segments increases, the method becomes more and more complicated and less and less practical. Consequently, the invention is described here with regard to conjugated two-segment filaments.

As used here, the term "conjugated filament" means a filament comprising a first longitudinal polymeric segment and a second longitudinal polymeric segment, which are arranged eccentrically in relation to the longitudinal axis of the filament and differ from each other with regard to the dimensional change properties in the longitudinal direction. The term "eccentric" as used here shall include both structures where the segments are arranged next to each other and asymmetric shell-core structures. The term "dimensional change properties in the longitudinal direction" means that when the filament is structurally stress-free, e.g. when it is in boiling water without being under any tensile stress, one of the segments will shrink or otherwise change length to a different extent than the other segment(s), which will be shown by the filament assuming a spiral shape or, if the segments are separate, in that the length of the individual segments is different. The formation of a spiral mug or the splitting of the filament in the above-mentioned experiment of course confirms the presence of at least two eccentrically arranged segments and likewise their different dimensional change properties. Conjugated filaments having segments that differ from each other with respect to their longitudinal dimensional change properties can be prepared by methods well known in the art, such as, e.g. when using polymers with different relative viscosities (see, for example, US Patent No. 3,536,802). There may be a distinct line of demarcation between the segments or, in some cases, only a gradual change in the composition of the filament across the cross-section.

In a preferred embodiment of the invention, the method is carried out using the arrangement shown in fig. 1. Referring to fig. 1, polyamides A and B with different final speed distances are coextruded at approximately the same melting temperature at a given speed (extrusion speed) in molten form through circular capillary openings 2 and 3 respectively in a spinning nozzle 1. The molten polymers are fed together under the spinning nozzle to form a molten stream 4 in which the polyamides A and B are arranged, as segments, next to each other. For purposes of illustration, only the production of one filament is shown in fig. 1. However, it will be understood that in the practical implementation of the invention the spinning nozzle will normally be equipped for the production of several molten streams, i.e. that the spinning nozzle will have several pairs of capillary openings 2 and 3. The molten stream 4 is then cooled in a conventional manner to form a filament (ie

a solidified, molten stream). The filament is then brought into contact with a coating application device 5 which applies a liquid coating to the filament. In cases where several filaments are produced, it is appropriate to feed the filaments together on the finish application device 5. The filament is then fed partly around a feed roller 6 and partly around a stretching roller 7 and is heated in a heating device 8 (e.g. a heated tube through which the filament is fed), after which the filament is collected by means of a collection device 9 (e.g. a spool on which the filament is wound). The roll 6 is turned with a peripheral speed of at least 1829 m per minute. The roller 7 is rotated at a peripheral speed which is greater than that of the roller 6, but is usually not greater than twice the peripheral speed of the roller 6. The partial guidance around the rollers 6 and 7 is carried out at an angle which is sufficient to prevent

that the filament slides on the rollers. When the filament is wound onto a spool, it must be wound at a speed lower than the peripheral speed of the roll 7 so that the filament is allowed to detune, (contract) before being wound. Otherwise, difficulties will arise when the spool is to be removed from the yoke on which it rotates, especially when the filament or yarn is applied in a large number of turns to the spool to form the lay-up unit. In cases where the filament is only passed a small number of times around the coil, the heating of the filament in the heating device 8 can be omitted. The filament which

is wound on the bobbin, normally has both original ripple (visible ripple) that becomes apparent when the spinning line is removed, and latent ripple that can develop during later processing

action of the yarn.

Fig. 2 shows the cross-section of a typical conjugated filament which is produced according to the method according to the invention, and where the ratio between segment A and segment B which is used to produce the filament is 1:1.

According to the preferred embodiment of the invention, the spinning-stretching process is carried out under such process conditions and using such polyamides that a filament is obtained which has a measurement value in the crimp test at high load of at least 15% and a crimp/shrink ratio of at least 2, with the preferred values being at least 20% and 3, respectively. In the following, the effect of changing the specified process variables while keeping all the other variables constant shall be explained.

One of the segments of the conjugated filament is preferably formed from a rapidly crystallizable fiber-forming polyamide, while the other segment is formed from a less rapidly crystallizing fiber-forming polyamide. This difference with respect to crystallisation can be achieved by choosing polyamides with different final velocity distances. Generally, it will be the case that with increasing difference between the final speed distance of the two segments, the measured value in the ripple test at high load will increase to or approach a maximum value, after which it will remain essentially constant. Generally, the polymers become less crystallisable with increasing ratios of homopolymeric segments to copolymeric segments. For example, the crystallisability of nylon 66 is higher than the crystallisability of nylon 66-6 (95:5), which in turn is higher than the crystallisability of nylon 66-6 (90:10), which is in turn higher than the crystallisability of nylon 66-6 (85 :15). Therefore, highly crystalline homopolyamides such as nylon 66 and nylon 6 are preferred, as nylon 66 gives the highest measurement values in shrinkage tests at high load and is therefore the preferred polyamide for use according to the invention. Nylon copolymers are referred to here in a conventional manner. For example, "nylon 66-6" means the copolymer consisting of 66 units -NH(CH2)gNHCO(CH2)4C0- and 6 units -NH(CH2)5CO-, the distribution of the units being random, formed e.g. by copolymerization of hexamethylenediammonium adipate and caprolactam. The values given in parentheses after the designation are mole ratios. For example, (95:5) means a molar ratio of 95:5.

When the polyamide used to form one of the segments of the conjugated filament is composed of structural, repeating units of the same chemical formula as the polyamide used to produce the other segment, by choosing polyamides that differ from each other with regard to to relative viscosity, achieve the desired result by the present method. When nylon-66 polyamides with different relative viscosities (RV) are used to form the segments, the difference in RV between the two nylon-66 polyamides must be at least 5, and it is preferably at least 15 and most preferably at least 30, as the relative viscosity of the high viscosity nylon-66 polyamide is at least 30, preferably at least 50 and most preferably at least 65.

Although nylon 66 is the preferred polyamide, other polyamides can also be used according to the invention. Examples of other suitable homopolyamides are nylon 6 and nylon 610. Examples of suitable copolyamides include, but are not limited to, those described in US Patent Nos. 3,399,108, 3,418,199, 3,558,760 and 3,667,207. Examples of such copolyamides are nylon 6-66, nylon 66-610; nylon 66-610-611-612?nylon 66-612;

nylon

nylon 66-6T

■units) nylon 66-6-612; nylon 6-66-

610 and nylon 6-612.

The spinneret can be constructed so that when a molten stream is formed, each of the molten polymers can be extruded through a separate capillary opening in such a way that the molten polymers are brought together at the front of the spinneret and form the molten stream, or the polymers can be brought together and then extrude through a common capillary opening in the spinneret to form the molten stream. However, it is preferred that the molten polymers are extruded through each capillary opening and brought together under the face of the spinneret to form the molten stream, as shown in fig. 1. Unless the molten polymers are brought together at or below the face of the spinneret, one segment (e.g., the low relative viscosity segment) will tend to wrap around the other segment (e.g., the high relative viscosity segment ), which in turn tends to reduce the final ripple properties of the filament.

The filament can have any desired cross-section, such as e.g. can be circular, three-lobed, etc. However, it is most economical to manufacture spinning nozzles with circular capillary openings. Filaments with a cross-section which is a consequence of the fact that capillary openings with a circular cross-section have been used are shown in fig. 2.

The volume ratio between the polyamide segments can vary within a wide range. For practical reasons, the segment system will normally fall within the range from 3:1 to 1:3. In the case where both segments are made of nylon 66, a ratio of approx. 1:1 to 1:3 (polyamide with high relative viscosity in relation to polyamide with low relative viscosity), the greatest degree of ripple being achieved with a ratio of approx. 30:70 (between the high relative viscosity polyamide and the low relative viscosity polyamide).

Cooling of the molten streams usually takes place

in a cooling chamber, which is usually referred to as a "chimney".

The term "cooling", as used here, means cooling of the molten streams to a sufficient extent that the streams solidify (ie become filaments). Although the cooling of the currents can take place with the assistance of a transverse air flow (or an air flow in the same direction), such an air flow is not necessary to obtain filaments with a high degree of ripple at high load.

In conventional processes, the filaments are passed from the cooling chamber through something called a "steam conditioning tube". Steam is circulated through the tube and comes into fine contact with the filaments. The purpose of the steam is to facilitate the subsequent processing of the filament. However, it has been shown that the use of conditioning steam in the spinning-stretching process according to the invention significantly reduces the ripple at high load, namely to a level that is significantly lower than 10%. Consequently, conditioning steam should not be used in the process when curling is desired under heavy load, or such steam must be used with great restraint.

Appretur (aqueous or anhydrous) can be applied to the filaments

in a conventional way, e.g. in that the filaments are passed over a roller which transfers the finish back to the filaments from a.be-

holder in which the roller is partially submerged and rotates. Alternatively, a stationary, V-shaped guide device can be used. The guiding device is arranged so that the filaments are pulled through the V-slot and a finish is dosed onto the filaments via a

small tube. An application is not required to achieve the desired filament properties. However, if no finishing is used, the filaments will become statically charged and difficult to handle, e.g. when they are unwound from a coil. For practical reasons, the finish is preferably an aqueous finish (water itself or a water-based finish) due to the environmental considerations that must be taken into account when using non-aqueous finishes.

It is convenient to bring the filaments together on the finish application device (eg the above mentioned finish application device). If desired, the filaments can be brought together by means of a conventional joining device after they have been cooled and before they have been recoated.

The molten streams are subjected to thickness reduction

and are accelerated from the spinneret (or - when formed below the spinneret, from the point of formation) by means of a feed roll which extracts the cooled streams (filaments) from the cooling zone at a spinner speed that is higher than the extrusion speed. The extrusion speed is the linear speed at which

the molten polyamide theoretically passes through the spinning nozzle capillary tube or capillary tubes and is calculated from the capillary tube dimensions, the extrusion speed and the density of the polyamide. When more than one capillary tube is used to form the filament, the average of the linear speeds is calculated, and the average speed is used as the extrusion speed.

With the term "jet attenuation"

=JA) means, as used here, the quotient obtained by

to divide the spinning speed (SS = spinning speed) by the extrusion speed (ES = extrusion speed). It has been shown that increasing the jet thickness reduction has little effect

on the ripple at high load. In order to obtain filaments with a high degree of crimp at high load, the spinning speed must usually be at least 1829 m per minute. Preferably, spinning speeds of at least 2286 m per minute, and preferably at least 2743 m per minute, when carrying out the method according to the invention. Generally, increasing the spinning speed and other process speeds will consequently improve the economic side of the process.

According to a preferred embodiment of the invention, the filaments are stretched in production lines, before they are collected, e.g. before they are wound up on a spool. If the filaments are collected and then stretched in a separate operation, the filaments will usually not achieve any significant degree of curl at high load, although they may possess a moderate degree of curl at light load. However, it has been found that if the filaments are spun and collected under anhydrous conditions and kept under anhydrous conditions for a limited time, until they have been substantially stretched, it is possible to obtain filaments with a degree of crimp at high load which is higher than 8%, although the stretching of the filaments is carried out in an operation which follows and is separate from the spinning operation. However, such conditions are not usually practical in commercial operations.

The stretching is preferably carried out using

an arrangement of rollers as shown in fig. 1, where roller 6 is a feed roller and roller 7 is a tension roller. The tension roller is driven at a peripheral speed that is higher than the peripheral speed of the feed roller. With the arrangement of rolls shown on

fig. 1, the filaments are stretched as they leave the feed roll 6.

As the stretch ratio is increased from 1, the degree of ripple at high stress imparted to the filaments will usually increase through a maximum value and then slowly decrease. Normally, maximum values are obtained in the ripple test at high load when the filaments are stretched at a ratio greater than 1.0. In many cases, a stretch ratio higher than 2.0 cannot be used without breaking the filaments. If desired, the stretching of the filaments can take place on the downstream side of the feed roll, e.g. between two pairs of rollers, of which the first pair is rotated at the same peripheral speed as the feed roller, while the second pair is rotated at a higher peripheral speed. Preferably, the filaments are stretched as soon as possible after they have been cooled. At spinning speeds of at least 1829 m per minute, stretching will occur within a fraction of a second after cooling. However, as mentioned above, stretching can be delayed for a long time (ie for several minutes and even hours), provided that the filaments are kept under anhydrous conditions. Under such conditions, a water-free finish must be used or no finish at all. When a significant delay (of more than 4 seconds) is introduced before the filaments are stretched, such as in a ripple chamber tower or by means of rollers around which the filaments are passed several times, a water-free finish is preferably used to ensure that the degree of ripple at heavy load is not significantly reduced. When the time between cooling and stretching is significantly longer than 4 seconds, it may also be necessary to keep the filaments in a water-free environment. Whether a water-free finish and/or a water-free environment gives satisfactory results can easily be determined experimentally. When the filaments are stretched within a few seconds of cooling, the use of an aqueous finish and the ambient conditions will have very little, if any, effect on the degree of high stress curl achieved by the process.

When carrying out the process commercially, it will normally be desirable to wind the filaments. onto a spool by means of a spooling machine operated at the lowest applicable speed which gives a sufficient stretch in the yarn to achieve a satisfactory winding on the spool. Usually, a stretch in the yarn of between 0.05 and 0.1 g per deny. Usually the difference between the peripheral speed of the tension roller and the speed of the winding machine is in the range from 2 to 12%. This difference in speed causes the yarn to unwind between the tension roller and the winder. When carrying out the process, conventional winding machines of the type which enable a pre-setting of the yarn tension can be used, so that the speed of the winding machine is automatically adjusted so that the pre-set yarn tension is maintained. In some cases, it may be desirable to heat the yarn while it is being relaxed, depending on factors such as the denier of the overall yarn, the size of the lay-up unit, processing speeds and the like. The heating of the yarn can be done by exposing the yarn to radiant heat, or by passing the filaments through an air-heated tube. The yarn will also be able to be heated by keeping the tension roller at a suitable temperature, so that the filaments are heated. Of course, the yarn must not be heated in such a way or to such a temperature that its ripple is reduced to a significant extent. In this respect, it has been found that the use of steam to heat the yarn tends to significantly reduce the degree of curling under heavy load. Therefore, it is not recommended to use steam to achieve thermal relaxation of the filaments in cases where a high

degree of ripple at high load.

Measurements

A. When relative viscosity (RV) values are given in this description, they are given without designation. First, the polymer's intrinsic viscosity [n] is determined, and then the relative viscosity (RV) is calculated from the equation:

[n] = (0.184) (RV)0.941 : solved with respect to RV:

RV = e raised to the following power:

The intrinsic viscosity is determined from the equation:

where t is the flow time at 25°C through a viscometer for 90% formic acid (pure solvent), and t is the flow time through the same viscometer for a solution of the polymer of concentration (c) in grams of polymer per 100 ml of pure solvent. For the determination of [n] for a polymer with a high RV, a concentration of 0.25 g per 100 ml. When determining [n] for a polymer with a low RV, a concentration of 0.50 g per 100 ml.

B. When ripple values obtained in the ripple test at high load are given in this description, they are given in percent (%), and they are determined on a sample of the filament or filaments before its or their latent ripple develops, namely in the following way:

(1) Determine the denier of the sample.

(2) Calculate the number of turns of a denier hessle coil that will be required to form a hessle (a continuous bundle of filaments in the form of a folded spiral) with a denier of 4000. (3) Make a hessle with a denier of 4000 based on the sample. (4) Suspend the line vertically from a stationary hook by placing the line over the hook, taking care not to stretch or tangle the line. Hook a light metal wire hook (reshaped paper clip) through the lower part of the clasp. (5) While the hessian hangs vertically down from the hook, an 800 g weight is hung on the metal wire hook (the hessian now has the appearance of an 8000 denier single strand). (6) After the weight has been suspended for 30 seconds, the 800 g weight is removed and replaced with a 20 g weight. (7) Suspend the hespen with 20 g of solder for 5 minutes in a 120°C oven with forced convection. (8) Remove the wire from the oven, let it cool for 1 minute and re-hang it over the stationary hook with the 20 g of solder hanging in the wire using the metal wire hook. (9) Then determine the length of the double buckle to the nearest 0.1 cm, without removing the 20 g of solder. Bring up this length (L-^) . (10) Remove the 20 g weight and replace it with an 800 g weight.

After 30 seconds, determine the length of the rope to the nearest 0.1 cm. List this length (L2)• C. When ripple values obtained in the light-load ripple test are given in this description, they are given in percent (%), and they are determined on a sample of the filament or filaments before its or their latent ripple develops, namely in the following way:

(1) Determine the denier of the sample.

(2) Calculate the number of turns of a denier hessian coil that will be required to form a hessian (a continuous bundle of filaments in the form of a folded spiral) with a denier of 5412. (3) Make a hessian with a denier of 5412 based on the sample. (4) Suspend the line vertically from a stationary hook by placing the line over the hook, taking care not to stretch or tangle the line. Hook a light metal wire hook (reshaped paper clip) through the lower part of the clasp. (5) While the hook hangs vertically from the hook, a 1000 g weight is hung on the metal wire hook (the hook now has the appearance of a 10824 denier single ts treng}, and after 0.5 minutes the length of the double hook is measured to the nearest 0.10 cm . Record this length as L-^. Remove the 1000 g of solder. (6) Hang the hesper in a forced convection oven and turn off 120°C for 5 minutes. (7) Remove the hesper from the oven, let it cool for 1 minute, attach a 10-g lead to the hook using the wire hook and re-hang it over the stationary hook with the 10-g lead hanging from the wire hook. (8) Then, without removing the 10-g lead, determine the length of the double loop to the nearest 0.1 cm. Enter this length as • (9) Unhook the 10 g solder and replace this with the 1000 g solder. Then, after 30 seconds, determine the length of the hook to the nearest 0.1 cm. Enter this length as L3.

D. When values for the shrinkage in boiling water are given

in this description, they are given as a percentage (%), and they are determined in the following way:

(1) Determine the denier of the sample.

(2) Calculate the number of turns of a denier bobbin coil that will be required to form a bobbin (a continuous bundle of filaments in the form of a folded spiral) with a denier of 2250. (3) Make a bobbin with a denier of 2250 based on the sample. (4) Suspend the line vertically from a stationary hook by placing the line over the hook, taking care not to stretch or tangle the line. Hook a light metal wire hook (reshaped paper clip) through the lower part of the clasp. (5) While the hessian hangs vertically down from the hook, a 1500 g weight is hung on the metal wire hook (the hessian now has the appearance of a 4500 denier single ts thread). (6) After the plumb bob has hung for 10 seconds, the length of the double buckle is determined to the nearest 0.1 cm, and the measured length is entered as (beginning length). (7) Replace the 1500 g lot with a 6.1 g lot and keep the hemp immersed in a boiling water bath for 1 minute. (8) Remove the hemp from the bath, unhook the 6.1 g solder and allow the hemp to air dry. After the hemp is dry, it is allowed to condition at standard atmospheric conditions (72% relative humidity) for 12 hours. (9) Re-hang the 1500 g soldered onto the hook while the hook hangs vertically down from the stationary hook. (10) After 10 seconds, determine the length of the double buckle to the nearest 0.1 cm and record this length as L f (final length).

E. Final velocity distance: According to one aspect of the invention, the method is carried out by coextrusion through a spinneret and two polymers (for example Polymer A and Polymer B) with different final velocity distance values,

wherein Polymer A and Polymer B are brought together to form a molten stream which is solidified in a cooling zone to form a filament, which is then subjected to thickness reduction and accelerated by pulling the filament from the cooling zone at a speed (spinning speed) of at least 1829 m per minute. The velocity of a molten stream increases continuously until the point where the stream solidifies. At this point the speed of the current corresponds to the spin speed. The final velocity distance for Polymer A is determined under the same conditions as for the coextrusion of Polymer A and Polymer B, except that in this case only Polymer A is extruded. A Laser Doppler Velocimeter using a He-Ne laser with optics for 9 mm beam separation and 250 mm focal length,

and which utilizes a counter-type signal processor Model 1980 manufactured by TSI, Inc. St. Paul, Minnesota or equivalent instrument) is used to determine the point at which the molten stream consisting entirely of Polymer A reaches its maximum or terminal velocity. The distance from the spinneret to this point is measured and recorded as the final velocity distance for Polymer A. The final velocity distance for Polymer B is then determined in the same way. The values for the final velocity distance are not in themselves of any great importance, as long as the values are different.

The following examples will further illustrate the invention. In the examples following Example 1, the yarns will be produced using the same general apparatus and the same general method as in Example 1. The specific conditions used are given in each individual example, together with the results obtained.

Example 1

This example illustrates the production of conjugated filaments according to the invention, in a case where a nylon 66 with a high relative viscosity is used for the production of one of the segments, and a nylon 6 6 with a lower relative viscosity is used for the production of the other segment.

A nylon 66 with a high relative viscosity (RV=82) and a nylon 66 with a lower melt viscosity (RV=41), having different values of the terminal velocity distance, are coextruded side by side in a 1:1 ratio using the arrangement of Fig. 1, except that instead of one pair of capillary openings, the spinning nozzle has seven pairs of holes (capillary openings) arranged along a circle, which holes each have a diameter of 0.51 mm. The extrusion temperature is 285°C, and the extrusion rate is 0.011896 ml per minute. second per capillary opening. A joining device (a pin which dispenses finish) is arranged 91.94 cm from the front of the spinneret. The finishing pin has a rectangular shape and has its longitudinal axis parallel to the thread line. The pin is provided with grooves that receive and guide the seven filaments together. Aqueous finish is dosed into the groove and in contact with the filaments that are brought together. The filaments are cooled en route to the finishing pin by means of a transverse flow (2.83 em) of air from the surroundings. The filaments are then pulled out in the form of a yarn. from the return point at 2858 m per minute (the spinning speed) by means of a driven roller (feed roller), around which the yarn makes part of a revolution. The feed roll is 19 cm in diameter and is arranged 6.1 m from the front of the spinning nozzle. The yarn is pulled from the feed roll at a speed of 4572 m per minute by means of a tension roller, around which the yarn also makes part of a revolution. The tension roller also has a diameter of 19 cm. The distance between the centers of the two rolls is 6 3 cm. The feed roller and tension roller are arranged so that the yarn does not slip on the rollers. The yarn is pulled from the tension roll and wound onto a spool using a conventional winding machine with a yarn tension of

1.0 g. On its way from the spool of the tension roller, the yarn passes between, but not in contact with, two heating elements (30.48 cm x

48 cm x 10.16 cm) placed directly opposite each other at a distance of 6.35 mm and heated to approx. 275°C. Between the tension roller and the bobbin, the yarn is relaxed to a degree corresponding to the quotient obtained by dividing the difference between the tension roller's peripheral speed (S-^) and the winding speed (S2) by

(S-^) , i.e.:

In this case the thermal relaxation is 0.098 or 9.8%.

Another yarn is produced and wound on a spool under the same conditions, except that in this case the heating elements are omitted from the process. The process conditions used for the production of the two yarn spools are summarized below:

Relaxation, in the production line, hot/cold: given in table 1.

The effect of eliminating the thermal relaxation is shown in Table 1.

where large layout units are required.

Example 2

This example shows that without stretching in the production line, it is not possible to produce yarn with ripples at high loads, even when high spinning speeds are used. Yarn is produced as described in example 1 using the following conditions:

The test results are listed in Table 2.

Example 3

This example shows that significant changes in the jet thickness reduction factor (JA factor) have little effect on the ripple at high load and the firmness. Yarn is produced as described in example 1, using the following conditions:

Relaxation, in the production line, hot/cold Hot (9.0%)

The test results are listed in Table 3.

The results listed in Table 3 show that increasing the JA factor by a factor of 4 only slightly increases the ripple at high load.

Example 4

This example shows the effect achieved on the curl and firmness when the feed roll speed (spinning speed) is varied from 1486 to 4572 m/s. minute, the stretch roll speed is varied from 2743 to 5486 m per minute and the stretch ratio in the production line from 1.1 to 1.85. The highest ripple values under load are achieved for spinning speeds (feed roll speeds) of 2743 m per minute and higher and for stretch ratios in the production line of 1.2 or higher.

In a first series of experiments, yarn is produced as described in Example 1, using the following conditions: The experimental results are listed in Table 4A

In a second series of experiments, yarn is produced as described in example 1 using the following conditions:

The test results are listed in Table 4B.

In a third test series, yarn is produced in the same way as in test series 4B, except that the melting ratio is different and the difference between the polymers' RV is much greater. The following conditions apply:

Relaxation/in the production line, hot/cold Cold The test results are listed in Table 4C.

In a fourth test series, yarn is produced in the same way as in test series 4C, except that the following conditions are used:

The test results are listed in Table 4D.

In a fifth test series, yarn is produced in the same way as in test series 4D, except that the melting ratio is different. The following conditions apply:

The test results are listed in Table 4E.

In a sixth test series, yarn is produced in the same way as in test series 4D, except that a stretch roll speed of 5486 m per second is used. minute. The conditions used are as follows:

The test results are listed in Table 4F.

Example 5

This example shows the effect of varying the ARV in the range from 24 to 34. Yarn is produced in the same way as in example 1, using the following conditions: Spinneret capillary openings (high/low), mm 0.25/0.25 Melting ratio ( high/low) 50/50

Nylon types (high/low) 66/66

Nylon's RV (high/low) Given in table 5

RV difference " " Feed roll speed (m per minute) 3048 Stretch roll speed (m per minute) 4572 Stretch, in production line (X) 1.5 Relaxation, in production line, hot/cold Cold (6.3%)

The test results are listed in Table 5.

The results in table 5 show that an increase in ARV

Naturally, the ripple increases with heavy loads.

Example 6

In this example, yarn is produced in the same way as in example 5. In this case, the relative viscosity of the polyamide with high RV is varied, while the relative viscosity of the polyamide with low RV is kept constant. The conditions used are as follows:

The test results are listed in Table 6.

In the same way as in example 5, the results show that the ripple at high load increases with increasing ARV.

Example 7

This example shows how variations in the melting ratio affect the ripple at high load and the ripple at low load. The yarn is produced as in example 1, using the following conditions:

The test results are listed in Table 7.

The results show that changes in the melting ratio have a significant impact on the ripple at high load and relatively little impact on the ripple at low load.

Example 8

This example illustrates the effects on the crimp obtained by steam conditioning the yarn. Yarn is produced in the same manner as in Example 1, except that the filaments are passed through a tube (steam conditioning tube) with a diameter of 12.7 cm and a length of 182.9 cm. The tube is placed 132 cm from the front of the spinning nozzle. Steam is introduced into the tube through openings arranged near the filament intake of the tube. The following conditions are used:

The test results are listed in Table 8.

The negative effects of steam conditioning on the ripple at high load are clearly shown in table 8.

Example 9

This example illustrates the use of spinnerets which are constructed in such a way that the polymer flows converge at a point other than under the front of the spinneret.

In a series of experiments, two yarns with different deniers (9AA and 9AB) are produced in the same way as in example 1, except that in this case a spinning nozzle is used in which the two angled capillary openings (polymer streams) meet at the front of the spinning nozzle instead of below the spinning nozzle front side, as fig. 1 shows. The following conditions apply:

The test results are listed in Table 9A.

In another series of experiments, two yarns (9BA and 9BB) are produced as described above, except that in this case each filament is produced by bringing the polymer streams together over the front of the spinning die, with subsequent extrusion of the combined streams through a common capillary opening in the spinning die. Also, the nylon-66 polymers have a relative viscosity of 28 instead of 14. The following conditions are used:

The test results are listed in Table 9B.

The results listed in Tables 9A and 9B show that other spinneret constructions than those where the polymers are brought together under the spinneret can effectively be used in the practice of the invention.

A comparison of the ripple values in table 9B with the ripple values in table 9A shows that in this case an increase in ARV leads to an increase in the ripple values.

Example 10

This example illustrates the production of yarn according to the invention, where the high-viscosity polyamide and/or the low-viscosity polyamide is a polyamide other than nylon-66.

In a series of experiments, yarn is produced from nylon 610 and nylon 66 using the following conditions:

The results are listed in Table 10A.

The results in table 10A show that acceptable ripple values are achieved when nylon 610 is used together with nylon 66 (yarn lOAA). The results also show the importance of ARV. Note that in experiment 10AB £ RV is not sufficiently large to

that a significant ripple value is achieved at high load.

In another series of experiments, yarn is produced from nylon 66 and nylon 6 using the following conditions:

The test results are listed in Table 10B.

In another series of experiments, yarn is produced from nylon 6, using the following conditions:

The test results are listed in Table 10C.

In another series of experiments, yarn is produced from nylon 66 and a nylon 66-612 (50:50) copolymer, using the following conditions:

The test results are listed in Table 10D.

In another test series, yarn is produced under the same conditions as in test series 10D, except that in this case the copolymer is the polymer with a high relative viscosity, while the homopolymer is the polymer with a low relative viscosity. The following conditions apply:

The test results are listed in Table 10E.

The results shown in Table 10E show the negative effects on boiling water shrinkage values that occur when the copolyamide is used as the high relative viscosity component.

In another test series, yarn is produced under the same conditions as in test series 10E, except that in this case the polyamides are:

The test results are listed in Table 10F.

Example 11

In this example, various "ready-spun" conjugated yarns are prepared at low spinning speed, using the apparatus described in Example 1 and the conditions given in Table 11A. The "finished spun" yarns are stored at ambient conditions and then stretched in a separate operation between tension rollers under conditions as indicated in Table 11B. The experimental results are also listed in Table 11B.

The results in Table 11B show that when the yarn is spun at a low speed and then stretched in a subsequent operation, the yarn does not acquire significant ripple at high load.

Example 12

This example shows the effect on the ripple at high load, which is obtained by using an aqueous finish, compared to that obtained by using an anhydrous finish, in cases where the stretching of the filaments is carried out in the production line, compared to post-stretching in a separate operation.

A series of yarns is produced in the same manner as in Example 1, using the following conditions:

The test results are listed in table 12.

The results listed in Table 12 show that a significant ripple at high load is lost if time elapses before the yarn is stretched, compare yarn 12A and B with yarn 12C and D and yarn 12E and F with yarn 12G with yarn 12G-J. The results also show that moisture has a negative effect on the ripple at high load for yarns whose stretching has been omitted (compare yarn 12C with yarn 12D), and that the effect has a more negative effect with increasing exposure to stretching (compare yarn 12D with yarn 12H- J).

The above examples show how important the choice and correlation of the process conditions and the choice of polymers with regard to melt viscosity, melt viscosity difference, polymer type, etc., are for the ripple values at high load.

Claims (27)

1. Filament which is practically free of torsional forces, characterized in that it comprises a first longitudinal polyamide segment and a second longitudinal polyamide segment which are arranged eccentrically along the longitudinal axis of the filament and differ from each other with regard to dimensional change properties in the longitudinal direction, which filament exhibits a measured value in the ripple test at high load of at least 12% and a measurement value in the shrinkage test in boiling water that is such that the quotient obtained by dividing the measurement value obtained in the ripple test by the measurement value obtained in the shrinkage test is at least 1. 2. Filament according to claim 1, characterized in that it consists of two segments arranged next to each other in the longitudinal direction of the filament. 3. Filament according to claim 2, characterized by the quotient being at least 2. 4. Filament according to claim 3, characterized in that the measured value in the ripple test is at least 15%. 5. Filament according to claim 2, characterized by the quotient being at least 3. 6. Filament according to claim 5, characterized in that the measured value in the ripple test is at least 18%. 7. Filament according to claim 2, characterized in that each segment essentially consists of a homopolyamide. 8. Filament according to claim 7, characterized in that each segment consists essentially of nylon 66. 9. Procedure/ characterized by stretching a fresh filament in a stretch ratio higher than 1.0, which filament has been melt spun at a spinning speed of at least 1829 m per m and comprises a first longitudinal polymeric segment and a second longitudinal polymeric segment which are arranged eccentrically along the longitudinal axis of the filament and differ from each other with regard to dimensional change properties, the difference in dimensional change properties and the stretch ratio being chosen so as to obtain a filament with a measured value in the ripple test at low load of at least 12%. 10. Method according to claim 9, characterized in that the difference in dimensional change properties and the stretch ratio is chosen so that a filament is obtained with a measurement value in the ripple test at low load that is at least 20%. 11. Method according to claim 10, characterized in that the stretching is carried out in the production line, immediately after the melt spinning and before the collection of the filament takes place. 12. Method of spinning and stretching for the production of a conjugated filament, characterized in that two molten fiber-forming polymers with different final velocity distances are coextruded to form a molten stream where the polymers are arranged eccentrically along the longitudinal axis of the stream, the molten stream is cooled and caused to solidify in a cooling zone to form a filament, the molten stream is reduced in thickness and is accelerated by withdrawing the filament from the cooling zone at a speed of at least 1829 m per minute and the filament is then stretched in the production line at a stretch ratio higher than 1.0 before it is collected, the process conditions and polymers being chosen so that a filament with a measured value in the ripple test at low load of at least 12% is obtained. 13. Method according to claim 12, characterized in that the process conditions and polymers are selected so that a filament is obtained with a measured value in the ripple test at low load that is at least 20%. 14. Method according to claim 12 or 13, characterized in that the speed is at least 2288 m per minute. 15. Method according to claims 12 - 14, characterized in that at least one of the polymers is a polyamide. 16. Method according to claims 12 - 15, characterized in that the polymers are brought together after the extrusion. 17. Method according to 12 - 16, characterized in that the filament has the mentioned segments arranged next to each other. 18. Method of spinning and stretching for the production of a conjugated filament, characterized in that two molten fiber-forming polyamides with different final velocity distances are coextruded to form a molten stream where the polyamides are arranged eccentrically along the longitudinal axis of the stream, the molten stream is cooled and caused to solidify in a cooling zone to form a filament, the molten stream is reduced in thickness and is accelerated by withdrawing the filament from the cooling zone at a speed of at least 1829 m per minute and the filament is then stretched in the production line at a stretch ratio higher than 1.0 before it is collected, the process conditions and the polyamides being selected so that a filament with a measurement value in the ripple test at low load of at least 12% is obtained, and such a measurement value for the shrinkage in boiling water that the quotient obtained by dividing the measured value for the ripple by the measured value for the shrinkage in boiling water is at least 1.0. 19. Method according to claim 18, characterized in that the polyamides are arranged next to each other along the filament. 20. Method according to claim 18, characterized in that the speed is at least 2743 m per minute. 21. Method according to claim 19, characterized in that the spinning conditions and the polyamides are selected so that a filament is obtained with a measured value in the ripple test of at least 15% and a quotient as indicated of at least 2.0. 22. Method according to claim 19, characterized in that the spinning conditions and the polyamides are selected so that a filament is obtained with a measured value in the ripple test of at least 20% and a quotient as stated of at least 3.0. 23. Method according to claim 19, characterized in that each of the polyamides is a homopolyamide. 24. Method according to claim 23, characterized in that one homopolyamide is nylon 66 and the other homopolyamide is a nylon 66 with a different relative viscosity. 25. Method according to claim 24, characterized in that the difference in relative viscosity between the two nylon materials is at least 30. 26. Method according to claim 24, characterized in that one nylon 66 has a relative viscosity of at least 50 and that the other nylon 66 has a relative viscosity that is less than 50. 27. Method according to claim 24, characterized in that one nylon 6 6 has a relative viscosity of at least 65 and the other nylon 66 has a relative viscosity that is lower than 65.