GB1593297A - Process for the production of filaments of caproactam and filaments produced thereby - Google Patents

Description

(54) PROCESS FOR THE PRODUCTION OF FILAMENTS OF CAPROLACTAM, AND FILAMENTS PRODUCED THEREBY (71) We, BARMAG BARMER MASCHINENFABRIK AKTIENGE SELLSCHAFT, a body corporate organised under the laws of Germany, of Remscheid-Lennep, Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The invention relates to a continuous melt-spinning and drawing processes. A process for the spinning of polymeric filaments at speeds of over 3,000 metres per minute and subsequent drawing is known from German Offenlegungsschrift No.

22 04 535. This process has come into use and proved itself to be excellent, for example in the production of polyester filament, especially polyethylene terephthalate. The strength values (breaking strength and breaking elongation of the filaments and yarns) are at least as good as those of conventional polyester filaments and varns, but with respect to aging stability, temperature stability and other textile properties, especially texturizing capacity, they are superior to the conventional products. The published process has afforded markedly increased production.

Likewise it was @ossible to obtain good results in the production of filaments of polyamide 6 (polycaprolactam) and polyamide 6,6 (poly-hexamethylene adipamide). However, polyamides, in particular the most generally used types (polyamide 6 and polyamide 6,6) have a tendency to crystallize already immediately after spinning and before the drawing. It has been anticipated, however, that in a high speed spinning processes there would be a lowering of the crystallimlv of the undrawn filaments and a more efficient subsequent drawing thereof. In the face of these expectations, the quality advantages achieved by the rapid spinning and drawing process according to German Offenlegungsschrift 2204 535 appeared comparatively slight and disappointing in the case of polyamides.Because these expected advantages did not materialize, rapid spinning and drawing was considered suitable for polyamide filaments only when it was possible, as in the draw-texturizing of polyester threads, to combine the drawing with a following processing operation (Chemiefasern 1976, page 500). The present invention is a further development of the rapid-spinning and drawing process according to German Offenlegungsschrift 22 04 535 as applied to polyamides whereby clearly improved filament qualities are achieved.

According to the invention there is provided a continuous spinning and drawing process for the production of filaments of polycaprolactam, which comprises spinning through a spinning nozzle molten polycaprolactam, which in the spun, solidified state has a solution relative viscosity,i rel. between 2.0 and 3.6, the solution relative viscosity being determined with a solution of 1 gram of spun polycaprolactam in 100 ml of 96% H2SO4 at 20"C, and the 71 rel. further being less than Qz2/467, in which Qz is a desired quality rating calculated by wherein a is the breaking strength of the spun polycaprolactam filaments in p/dtex and E is the elongation at break of the filaments expressed as percent, taking oft the spun polycaprolactam filaments from the spinning nozzle at a take-off velocity above 3,500 meters per minute, and thereafter, immediately after their exit from the spinning zone, drawing the solidified filaments in a drawing zone at a draw ratio of from 1:1.1 to 1:1.5.

With polyamide 6 the spinnable, linear high polymers are obtained by polymerization of E-caprolactam-polycaprolactam (cf. also Koch, Faserstofftabllen Polyamidfasern in Chemiefasernftextllindustrie 1975, pp. 1013 ff and 1093 ff). The polymerization of the E-caprolactam can be controlled by modification of the polymerization process and by addition of polymerization regulators and stabilizers up to a certain degree of polymerization. The most widespread production process for polyamide 6 is the so-called "VK process".Here, the caprolactam, dissolved in a little water is continuously polymerized in a tube reactor at temperatures rising as high as 260"C. Thereafter the unreacted caprolactam or lower oligomers thereof are washed out to a residual concentration of less than 1% and thereupon the moisture content is reduced to less than 0.1%.

A measure for the degree of polymerization is the so-called solution viscosity measurement. Solution viscosity generally means, and does for purposes of this invention, the relative viscosity.

The following relationship is applied: 71 L Viscosity of the solution 9'eel. = 110 Viscosity of the solvent For the standardization of the method of measuring the solution viscosity, or relative viscosity, of polyamide 6, in Europe, 96% sulphuric acid (H2SO4) is frequently used as solvent, and the viscosity of a solution of 1 g of polyamide 6 per millilitres of H2SO4 is compared to the viscosity of the 96% sulphuric acid. For this, the run-through times of the solution and of the sulphuric acid are determined in an Ostwald capillary viscosimeter at a temperature of 20"C. The ratio of the runthrough times then yields the value of 17 rel.

Run-through time of the solution ?1 rel. = Run-through time of H2SO4 (96%) This definition of 11 rel. also applies to the invention herein.

In Anglo-American countries, the determination of the solution viscosity generally involves use of standardized formic acid. It is also a usual practice to determine the limit viscosity of "intrinsic viscosity" or the melt viscosity of the polymer. For the conversion of the various viscosity data reference is made to the relevant literature (G. Schulz, "Die Kuststoffe", 1964, page 427, Fourné, "Synthetische Fasern", 1964, page 364). This holds also for the relation between viscosity and molecular weight or between viscosity and K value according to Fikentscher's equation.

The solution viscosity of the material used can, as experience has shown, change by after-polymerization or depolymerization (decomposition) in the spinning installation. This change is dependent on the spinning process and the spinning installation. Determinative for the good filament or yarn qualities, however, is the viscosity of the freshly spun filaments or of the freshly spun capillaries after they exit from the spinning nozzle. This viscosity agrees essentially with the relative viscosity of the finished filaments. "Viscosity" in the context of this invention, therefore, is the relative viscosity of the freshly spun, hardened filaments. Knowing this viscosity it is usually possible for the skilled artisan to determine the change of viscosity attributable to the after-polymerization or depolymerization to be expected in a particular spinning installation and spinning process, by use of a material of known relative viscosity and by measuring the viscosity of the freshly spun filaments and then converting the viscosity value determined according to this invention to the viscosity value to be used having regard to the depolymerization or after-polymerization to be expected for the material used. The changes of relative viscosity in the melt spinning of polyamide 6 by means of extruders are expected essentially to be less than 0.02.

To determine the viscosity parameters according to this invention the socalled quality number Qz is used. Qz is defined as Qz = @## wherein: a is the breaking strength (tensile strength) of the filament(s) in p/dtex. This breaking strength is prescribed by the filament manufacturer in dependence on the use conditions for the filaments. It is determined from the tension at which the filament(s) break (breaking force), divided by the initial denier.

E iS the elongation at break in per cent and is likewise prescribed by the filament manufacturer according to the use conditions of the filament(s). It is determined as #1 # = 1o in which #1 is the filament elongation for a force lying 5% under the breaking strength, and 1o is the initial length of the unstressed filament(s).

The strength examinations were carried out on a "Statimat" apparatus from the form of Textechno, Herbert Stein, Mönchengladbach, at normal climate conditions (20 , 65% air humidity) with 500 mm clamp-in length and observance especially of DIN standards 53,834 and 53,815.

The quality number Qz is largely constant for filaments spun under particular spinning conditions. This means that the breaking strength and the elongation at break can be adjusted by the cooled filament drawing and other after-treatment only in reciprocal dependence. A filament of high elongation at break, therefore, will have only a low strength and, conversely, a filament of high tensile strength will have only a low elongation at break. If, with this interrelationship with high breaking strength, there are also to be obtained good drawing values, it was hitherto necessary to bring about an increase of the quality number by polymer selection, higher polymerization, after-polymerization and similar polymer-related measures.For this reason the viscosity for textile filament, threads or yarns with their ordinarily low requirements was prescribed for polyamide 6 at 2.3, while in the case of tyre cord filaments or yarns (or in other special areas of application), which demand higher tensile strength and elongation at break values, viscosities over 3.0 are necessary.

The essence of the invention resides in the fact that the absolute material dependence of the quality number is for the first time broken through and with maintenance of certain spinning conditions it is possible to prescribe as low as possible a viscosity by prescribing a minimum quality (Qz).

According to the invention the solution viscosity of the polymer composition is determined from the quality requirement, i.e., by prescribing the quality number with the provision that the solution viscosity is less than Qz2/46?. Qz is prescribed by the filament manufacturer. A proven preferable empirical viscosity range is: Q2 Q2 < TI < 784 484 For economic reasons it is desirable for 11 to lie in the lower part of this range and in the range:

On the other hand, the viscosity of the freshly spun filaments in present day known spinning installations, as is generally well known to the skilled artisan, must not go below a certain value. Otherwise the melt is no longer filament-forming and spinnable. This limit value lies at about rl = 2.On the other hand, for technical and specialized filaments, neither can the viscosity be arbitrarily increased. For technical and economic reasons, the solution viscosities of the freshly spun filament must not be more than about TI = 3,6 in the case of polyamide 6. There is vielded, accordingly, as second conditlon for the prescribing of the viscosity an upper limit of rl = 3.6 and a lower limit of tl = 2.0. Further, the process of the invention, for reasons of the experimental technology, could be verified only for extension values of 15 ES, 40.

Finally, for test purposes, a draw of 3% < He130 < 10% was always used in the drawing zone, with a minimum temperature of the second godet of 1300C, in order to reduce the filament breakages to an acceptable level. Likewise, it was ascertained that by raising the temperature of the godet mechanism engaged at the beginning of the drawing zone, it was possible to achieve a further lowering of the viscosity while maintaining a constant quality rating or with equal viscosity to achieve an increase of the quality rating.

By using the process of the invention it is possible for the skilled artisan in the field, according to the indicated equation, to select a viscosity for the polyamide 6 to be used, which viscosity is appropriate for the required quality range of the product and, in so doing, to use a low value hitherto not attainable for the solution viscosity. There is provided, accordingly, not only a computation procedure for the viscosity to be used, but through application to a particular spinning process there is made possible, too, the use of a polyamide 6 of an extremely low viscosity.

An advantage of the process of the invention is the reduction of production costs both in the polymerization and in the spinning, because the low viscosities made possible are equivalent to a low polymerization degree of the spun filaments.

The invention further involves the discovery that, at the determined viscosity, the take-off speed must be above 3,500 metres per minute if the prescribed qualities are to be attained. The take-off speed is defined as the speed of the third conveyance mechanism in the filament path. Such conveyance mechanisms are usually godet mechanisms which are encircled several times by the filaments.

Preferred take-off speeds are between 3,800 metres per minute and 5,500 metres per minute. Above 5,500 metres per minute, as is mentioned also in the literature, a very high orientation of the filaments is obtained, so that a modification of the breaking strength and elongation at break through the post-spinning drawing is presumably no longer possible.

It has been found that the extrusion rate and the ratio between extrusion speed and take-off speed are largely uncritical, so that conventional values of filament conveyance velocity, extrusion velocity and spinning nozzle aperture size can be used in this invention.

Also the filament treatment in the spinning shaft has proved uncritical for the achievement of the advantages of the invention. In tests which were carried out. a blowing and cooling zone oflength 1.5 metres, in which air was blown to cool and harden the molten filaments was following by a spinning shaft of 3 metres in length.

In the blowing zone the molten filaments were cooled by an air stream moving transversely to the filament direction at a flow velocity of 24 metres per minute and at room temperature. The heating of the filaments after emergence from the spinning nozzle or the reheating of the already hardened filaments at the end of the spinning shaft has proved to be substantially without effect upon the process of the invention. The filament finishing, as usual, took place between the lower end of the thread shaft and the first godet.

Substantial changes of the quality rating did not result from the presence or absence of filament finishing at the exit from the spinning shaft. The purpose of the filament finishing was to facilitate winding.

The drawing of the running filaments occurs as they leave the abovementioned first conveyance mechanism (for example a godet mechanism, godet or roll) in a continuous operation. Advantageously. the first godet mechanism is used as the delivery mechanism for the drawing zone and a second godet mechanism, driven at higher peripheral velocity, is used as drawing mechanism. The draw ratio, which lies according to the invention between 1:1.1 and 1:1.5, is defined as the ratio of the peripheral velocities of the first godet mechanism and of the drawing mechanism, i.e., the second godet mechanism. The maximum draw ratio depends, as is well known, on the take-off speed at which the filaments are taken off by the first conveyance mechanism (for example the first godet mechanism) from the spinning zone. An example for the dependence of the maximum draw ratio on the take-off velocity is given in Fig. 5 of the accompanying drawings. The maximum draw ratio is also dependent on viscosity, filament denier and other influencing factors. The drawing actually used must be less than the maximum draw ratio and is selected in such a way that the breaking strength and the elongation at break attain the desired values, i.e., by a compromise between breaking strength and elongation at break for the desired filament quality. Fig. 5 shows the drawing conditions with which there was achieved an elongation at break of 36% for textile filaments.

The use in the invention of a particular relationship between the polymer viscosity, the spinning process, the drawing process and also a shrinkage step, if used, enables very good quality rating to be achieved, whereby the compromise between breaking strength and elongation at break provides more easily the desired minimum values for breaking strength and the admissible or desired values for the elongation at break, The drawing can be hot or cold, i.e., with or without heating of the solidified filaments. A drawing pin or similar device for establishing a draw point is not needed, which is especially advantageous as regards machine technology and the use of the process on an industrial scale.

Cold drawing does not impair the quality ratings. Hot drawing, however, is preferred, especially to reduce filament and capillary breakages, to reduce the drawing forces needed and to reduce the shrinkage tendencies of the filaments.

Advantageously the heating takes place on the first godet mechanism of the drawing zone with the godet at a temperature of between 40 and 1000C in the case of polyamide 6. Heating by means of a godet has the advantage that, through a suitable number of filament encirclings, sufficiently long contact times are obtainable to bring the filaments to the desired temperature. It is essential to the invention that the drawing process should immediately follow the spinning process.

Otherwise, the desired filament qualitites cannot be achieved.

A shrinking step may follow the drawing process in a continuous manner. Here the filaments leaving the drawing zone are allowed to shorten in correspondence to their shrinkage tendency. The shrinking can take place between the drawing mechanism, i.e., the second godet mechanism and the winding or coiling mechanism. It is especially advantageous, however, to have the drawing zone followed by a shrinking zone which consists of the exit side of the drawing mechanism (second godet) and of a further third godet mechanism (heated or unheated), which is driven at a lower peripheral velocity. It is also advantageous to promote the shrinkage tendency by heating the filaments. For heating at this stage, many types of heating arrangements can be used, such as hot plates or hot air chambers.Advantageously the second godet is heated to a temperature for a polyamide 6 of from 1300C to 2000C, preferably from 160"C to 200"C. By heating the second godet, the heating of the filament can be achieved with a device which is inexpensive and which affords sufficiently long residence times. The shrinkage is advantageously to between 3 and 10%, i.e., the peripheral velocity of the third godet lies is between 3 and 10% lower than the peripheral velocity of the second godet mechanism. It has proved that for the production of high quality filaments, the relationship of the 17 value to the temperature of the second godet mechanism is also important.

The shrinkage treatment can also be subdivided so that it occurs partially in the above-described shrinkage zone, with the remainder occurring by virtue of a corresponding reduction in winding velocity permitting further shrinkage of up to 5%. This permits winding or coiling of the filaments at a low tension, thereby lessening possible damaging of the filaments and/or the winding and also achieving better run-off of the filaments.

For the production of filament cables which have deniers of several tenthousand dtex, an embodiment of the process of the invention provides a process in which each spun fibre bundle is continuously drawn in its own drawing zone, each consisting of a first and second godet mechanism, and only thereafter are the filament bundles combined by plying into a cable and deposited in a collector, e.g., a can, box or barrel. If need be, a shrinkage treatment for each filament bundle can take place before plying, again in each case in a separate shrinkage zone, which then consists preferably of respective second and third godet mechanisms. The shrinkage also can take place after plying, i.e., between the second godet mechanism and the collective take-off mechanisms through which run the filament bundles being plied into a cable.For this the peripheral velocity of the take-off mechanism should be from 3 to 12% less than the peripheral velocity of the particular second godet mechanisms. Further, it is also possible to carry out a first shrinkage in a shrinking zone provided separately for each filament bundle and to carry out an after-shrinkage between the last godet mechanism of the respective shrinkage zones and the collective take-off mechanism.

The process of the invention can be employed advantageously to produce continuous filaments and cables thereof in the capillary range of from 1.5 to 10 dtex and in the predominant total denier range of 10 .o 200 dtex for textile deniers, from 300 to 3000 dtex for high-strength deniers ar 1 from 10,000 to 100,000 dtex for filament cables.

The resultant filaments and cables are of high quality, are produced rapidly according to the invention, and have especially favourable chemical, physical and technical properties. These chemical physical, technical and quality factors in relation to the time spent to produce a unit quantity may be expressed mathematically by a quality quotient: Quality rating Quality quotient (Qq) (Solution viscosity) wherein, as earlier stated: Quality rating (Qz) = Solution viscosity = 71 rel.

The solution viscosity of the solidified filaments just after emergence from the spinning nozzle agrees with that of the finally drawn and/or shrunk filaments. In filaments which are produced according to the process of this invention, the quality quotient is higher than in all filaments hitherto known.

The unexpected gain in quality with use of low viscous materials and use of the spinning and drawing conditions of the invention is thought to be based on the fact that, with the high draw-off speeds according to the invention and with the drawing following spinning extremely quickly in the continuous process, the rate of crystallization of the polymer is not sufficient to bring about, for polyamide 6, the natural and expected crystallization before the drawing process. It is therefore possible with the process of the invention, to bring the polyamide 6 thread to the drawing without Drevious crvstallization and thereby to achieve a very susbtantial improvement in the strength properties of the filaments produced.

In the accompanying drawing: Fig. I is a schematic representation of apparatus for performing the continuous spinning-drawing process of the invention with winding of the filaments produced; Fig. 2 is a similar schematic representation of an apparatus for performing the spinning-drawing process of the invention with a filament shrinkage zone; Fig. 3 is a schematic representation of an apparatus for carrying out the spinning-drawing process of the invention in the production of filament cables; Fig. 4 is a similar schematic representation of apparatus for carrying out the spinning-drawing process of the invention in the production of filament cables with respective filament shrinkage zones for the individual filament bundles; and Fig. 5 is a graph illustrating the dependence of the maximum draw ratio and of the draw ratio of the take-off speed to obtain an elongation at break of 36% for polyamide 6 filaments.

Fig. 1 shows an extruder 1 in which polyamide 6 cuttings are melted and supplied under high pressure to a spinning head 2. The spinning head 2 includes a spinning nozzle plate, from which is spun a plurality of individual filaments. The individual filaments are subjected to blowing by cooling air directly under the spinning nozzle plate in a blowing and cooling zone 3. They then pass through a spinning shaft 4, emerge as a filament bundle, are moistened by a finishing godet 5 and are drawn off by a first conveyance mechanism, the first godet mechanism 6.

The mechanism 6 comprises a first godet 6.1, which in the preferred embodiment of the invention, is heated. The godet 6.1 and a guide roll 6.2 are encircled several times by the filament bundle, which is then fed to a second godet mechanism, the drawing mechanism 7. This second godet mechanism is driven at a peripheral velocity which is higher by the prescribed draw ratio than is the peripheral velocity of the first godet mechanism 6.The winding arrangement consists of a friction drive roller 8, a transverse mechanism 10, a motor 9 and a bobbin or winding package 11.

The drive roller 8 drives the bobbin or package 11 at a constant peripheral velocity, which may be lower than the peripheral velocity of the second godet mechanism 7 so that the filament can shrink.

The apparatus shown in Fig. 2 is similar. Following the drawing mechanism 7, however, is a third godet mechanism 12 whose peripheral velocity is from 3 to 10% lower than the peripheral velocity of the godet mechanism 7, and which is preferably heated.

Fig. 3 shows a spinning and drawing apparatus for producing filament cables according to an embodiment the process of the invention. In each of the individual spinning shafts 4 is spun a respective filament bundle having a denier of, for example, 4,000 dtex. Each individual bundle is then drawn through its own drawing zone consisting of a first godet mechanism 6 and a second godet mechanism 7.

Thereupon, the individual bundles are caused to run in the same direction by deflection rolls 13 and are plied and fed collectively to a take-off mechanism 14.

Between the godet mechanism 7 and the mechanism 14 the plied bundles can, if necessary, shrink, by setting the peripheral velocity of the draw-off mechanism 14 at from 3 to 10% lower than that of the godet mechanism 7. A liquid finish may be applied, if desired, to the plied bundle by a finishing roller 19.

After the draw-off mechanism 14, the filaments collectively pass through a rotating tube 15 driven by a motor 18. In passing through the curved passage of the tube 15, the filaments are twisted into a cable which is laid in the form of superposed coils 17 in a can or container 16. The can or container 16 preferably is given an eccentric motion or a dual vector linear motion, which is represented by arrows 21.

Fig. 4 shows a similar spinning and drawing installation for producing cables.

in which a shrinkage treatment for each individual filament bundle takes place between the godet mechanisms 7 and 12. Depending on the draw-off velocity of the draw-off mechanism 14, a further after-shrinking can take place between the godet mechanisms 12 and the draw-off mechanism 14.

In test certain yarn qualities were predetermined with respect to minimum breakage strength and elongation at break range as well as minimum quality rating.

From these, according to the invention, there was determined the lowest possible solution viscosity for the freshly spun filaments and then in a spinning and drawing test it was ascertained under which spinning and drawing conditions the prescribed quality values could be attained.

Test I: Normal-strength polyamide 6 filaments were to be produced, for textile purposes, of 44 dtex flO with a minimum strength a of 5.5 p/dtex and about 30% elongation at break (E). From this the prescribed quality rating is given as Qz desired = a= 5.5 'v/30 = 30.2 From this according to the conditions prescribed by the invention, the solution viscosity of the spun thread was computed as Qz2 # = = 1.96.

467 Since polyamide 6 with a solution viscosity of 1.96 is not spinnable, there was chosen a solution viscosity of 2.2. For the spinning installation used and the meltspin process used, no after-polymerization or depolymerization was found.

This material was spun at various spinning velocities and with various draw ratios. The results are given in Table I. The first godet mechanism was in one case heated and in another case unheated, without there being substantial changes of the quality rating; From Table lit can be seen that in the take-ofl velocity range of above 3,000 metres per minute and especially over 3,500 to 3,800 metres per minute despite very low solution viscosities and solution viscosities insufficient for usual processes, the prescribed quality was achieved and indeed exceeded. The test was carried out with the second godet mechanism at a temperature of 200"C.

Test II: As test I, except that the filaments were not drawn immediately after the spinning, but were first wound and then after 24 hours taken off from the bobbins and drawn between the godet mechanisms 6 and 7 shown in Fig. I and rewound.

The test results are shown in Table II. It is evident from Test II that a raising of the quality ratings is possible only in a continuous process.

Test III: Table III shows results obtained by repetition of Test I at a draw-off velocity of 3,800 metres per minute, a draw ratio of 1:1.42, and three temperatures of the second godet mechanism.

Above 6,000 metres per minute take-off speed a spinning which was safe in operation with the equipment on hand was no longer possible.

Test IV: In Test IV high-strength filaments with high technical specification, 900 dtex f 180, were spun. The filaments were to have a strength of 7.5 p/dtex and an elongation at break in the order of 25%, and accordingly, therefore, a quality rating of 32.5. From this was derived as follows: Qz2 1410 # < = = 3.0 for the spun filaments 467 467 Q 2 TI > = 2.52.

567 To take into account possible depolymerization in the spinning installation 0.02 was added. A polyamide 6 was used which has a solution viscosity of 2.8. The results of Test IV are shown in Table IV Test V: In a further test, filaments produced in tests I and IV having approximately equal thread properties were analysed. From these analyses was derived the quality quotient.

It proved here that the quality quotient of the filaments produced in Test II at usual velocities and high viscosity was always below 22, while for the filaments similar with respect to their stength properties from Test I, which were produced according to the invention, the quality quotients were above 22 (cf. in this connection Table V).

TABLE I TEST I

Comparison tests Take-off velocity, m/min 1,000 2,000 3,000 3,800 4,000 5,000 5,500 Draw ratio, 1: 3.1 3.6 2.18 2.5 1.4 1.6 1.34 1.42 1.3 1.18 1.14 Breaking strength, 3.45 4.6 3.9 5.8 4.95 5.7 5.6 6.4 6.3 6.1 6.4 # Elongation at break, 49.5 29 40.5 21.8 38 30 39 32.8 34.5 37.8 33.5 # % Attained quality 24.6 24.9 24.8 24.0 30.4 31.2 35 36.5 37.5 37.5 37.2 number (Qz) Results: attained Below About Better Better Better Better (Qz) vs. desired same (Qz) TABLE II TEST II # rel. and other values as Test I except a) no drawing and b) discontinuous drawing

Take-off 3,800 4.000 5,000 5,500 velocity, m/min. a b a b a b a b Draw ratio, 1: 1.35 1.48 1.0 1.3 1.0 1.18 1.0 1.12 Breaking strength # 4.5 5.4 3.3 6.0 3.98 5.3 4.25 5.6 Elongation at break @ 31.5 26 74.3 22 52 27.2 45 25.3 Qz attained 25.5 27.5 28.6 28 28.5 27.8 28.5 28 TABLE III TEST III

Take-off velocity, m/min 3,800 3,800 3,800 Draw ratio 1: 1.42 1.42 1.42 Temperature, 170 180 200 2nd godet, C.

Breaking strength 5.8 6.1 6.4 # [p/dtex] Elongation at break # [%] 31.1 34 32.8 Quality number, (Qz) 32.4 35.6 36.5 TABLE IV TEST IV

Example No. 1 2 3 4 5 6 7 8 9 10 Take-up velocity, m/min 600 2,600 3,600 4,600 5,600 Draw ratio, 1: 3.56 3.7 1.35 1.5 1.25 1.44 1.0 1.3 1.0 1.2 Breaking strength, # [p/dtex] 4.8 6.15 4.2 6.1 5.4 6.9 4.0 7.0 4.95 7.5 Elongation at break, # (%) 45 28 52 26 49 31 64 29 42 26 Attained quality number, 32.2 32.5 30.3 31.1 37.8 38.4 32.0 37.7 32.1 38.2 (Qz) Results : attained Under About Better Better Better (Qz) vs. desired same (Qz) Examples 5,6,8 and 10 above are according to the invention, whereas Examples 1 to 4, and 7 and 9 are not.

TABLE V TEST V

Comparison test Solution viscosity, TI rel. 2,8 2.2 Test IV I Take-up velocity, m/min. 600 4,000 Draw ratio, 1: 3.7 1.3 Production velocity, m/min. 2220 5,200 Breaking strength, o'p/dtex 6.15 6.35 Elongation at break, s % 28 34.5 Quality number, (Qz) 32.6 37.5 Quality quotient, .19,5 26.3 Qq = Qz s WHAT WE CLAIM IS: 1.A continuous spinning and drawing process for the production of filaments of polycaprolactam, which comprises spinning through a spinning nozzle molten polycaprolactam, which in the spun, solidified state has a solution relative viscosity TI rel. between 2.0 and 3.6, the solution relative viscosity being determined with a solution of 1 gram of spun polycaprolactam in 100 ml of 96% H@SO@ at 20 C., and the # rel, further being less than Qz2/468, in which Qz is a desired quality rating calculated by ### wherein # is the breaking strength of the spun polycaprolactam filaments in p/dtex and # is the elongation at break of filaments expressed as percent, taking of the spun polycaprolactam filaments from the spinning nozzle at a take-off velocity above 3,500 meters per minute, and thereafter, immediately after their exit from the spinning zone, drawing the solidified filaments in a drawing zone at a draw ratio of from 1:1.1 to 1:1.5.

2. A process as claimed in claim 1 wherein the said solution relative viscosity is in the range of Qz2 Qz2 < TI < 784 484 3. A process as claimed in claim 1 wherein the said solution relative viscosity is in the range of Qz2 60Qz Qz2 +6.1 < # < 215 215 484 4. A process as claimed in claim 1 wherein the said solution relative viscosity is in the range of from

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (19)

1. **WARNING** start of CLMS field may overlap end of DESC **.

   TABLE V TEST V

   Comparison test Solution viscosity, TI rel. 2,8 2.2 Test IV I Take-up velocity, m/min. 600 4,000 Draw ratio, 1: 3.7 1.3 Production velocity, m/min. 2220 5,200 Breaking strength, o'p/dtex 6.15 6.35 Elongation at break, s % 28 34.5 Quality number, (Qz) 32.6 37.5 Quality quotient, .19,5 26.3 Qq = Qz s WHAT WE CLAIM IS: 1.A continuous spinning and drawing process for the production of filaments of polycaprolactam, which comprises spinning through a spinning nozzle molten polycaprolactam, which in the spun, solidified state has a solution relative viscosity TI rel. between 2.0 and 3.6, the solution relative viscosity being determined with a solution of 1 gram of spun polycaprolactam in 100 ml of 96% H@SO@ at 20 C., and the # rel, further being less than Qz2/468, in which Qz is a desired quality rating calculated by ### wherein # is the breaking strength of the spun polycaprolactam filaments in p/dtex and # is the elongation at break of filaments expressed as percent, taking of the spun polycaprolactam filaments from the spinning nozzle at a take-off velocity above 3,500 meters per minute, and thereafter, immediately after their exit from the spinning zone, drawing the solidified filaments in a drawing zone at a draw ratio of from 1:1.1 to 1:1.5.
2. 2. A process as claimed in claim 1 wherein the said solution relative viscosity is in the range of Qz2 Qz2 < TI < 784 484
3. 3. A process as claimed in claim 1 wherein the said solution relative viscosity is in the range of Qz2 60Qz Qz2 +6.1 < # < 215 215 484
4. 4. A process as claimed in claim 1 wherein the said solution relative viscosity is in the range of from

   Q2 Q2 to 567 484
5. 5. A process as claimed in any preceding claim wherein the polycaprolactam filaments are drawn from the spinning zone by running the filaments about a first godet mechanism rotating at a peripheral velocity of at least 3500 metres per minute.
6. 6. A process as claimed in claim 5, wherein said peripheral velocity is from 3,800 to 5,500 meters per minute.
7. 7. A process as claimed in claim 5 or 6, wherein the drawing of the filaments is carried out at a filment temperature of from 40 to 1000C.
8. 8. A process as claimed in claim 7 wherein the godet of the first godet mechanism is heated to 400 to 1000C, the said first godet mechanism being the beginning of the drawing zone.
9. 9. A process as claimed in any one of claims 5 to 8, wherein a second godet mechanism receives filaments from the first godet mechanism and at a higher peripheral velocity than the first godet mechanism to effect drawing of the filaments in the stretching zone, the godet of the second godet mechanism being heated to a temperature above 1300C.
10. 10. A process as claimed in claim 9, wherein the temperature of the second godet mechanism is between 180 and 200"C.
11. II. A process as claimed in claim 9 or 10, wherein the drawn filaments pass from the second godet mechanism to a third godet mechanism rotating at a lower peripheral velocity than the second godet mechanism to allow the filaments to shrink in a shrinkage zone between the second and third godet mechanisms.
12. 12. A process as claimed in claim 11 wherein the shrinkage of the filaments in the shrinkage zone is between 3 and 10%.
13. 13. A process as claimed in claim 11 or 12, further comprising winding the filaments after their passage through the shrinkage zone at a velocity providing for a further shrinkage of the filaments by up to 50/
14. 14. A process as claimed in claim 1, comprising simultaneously operating a plurality of said processes, and immediately after the drawing of the respective filament bundles, plying the filament bundles into a filament cable, and depositing the cable without tension.
15. 15. A process as claimed in claim 14, comprising passing the respective filament bundles through a filament shrinkage zone after drawing but before plying.
16. 16. A process as claimed in claim 13 or 14, comprising passing the plied filament bundles through a filament shrinkage zone before they are deposited as a cable.
17. 17. A continuous spinning and drawing process as claimed in claim 1, substantially as herein described with reference to any one of the Figures of the accompanying drawings.
18. 18. A continuous spinning and drawing process as claimed in claim I, substantially as herein described with reference to any one of the Examples given in Test I, Test III or Test IV.
19. 19. Polycaprolactam filaments when produced by a process as claimed in any preceding claim