CA2137375C - High speed spun filament yarns based on polycaprolactam and production thereof - Google Patents

Abstract

Filaments with a relative viscosity RV of 2.0 to 3.0 (measured at a concentration of 1 g of fibres per 100 ml in a 96 wt %
sulphuric acid, based on polycaprolactam, obtainable by:(a) extruding a melt consisting essentially of caprolactam through a spinning nozzle to form caprolactam filaments;(b) cooling the filaments thus produced and (c) drawing the cooled filaments off at a rate of at least [3600 + 1250.(3.0-RV)]m/min, the polycaprolactam used being produced in the presence of at least one bicarboxylic acid from the group: C4-C10-alkane bicarboxylic acids, C5-C8-cycloalkane bicarboxylic acids, benzole and naphthaline bicarboxylic acids which may have up to two sulphonic acid groups and whose carboxylic acid groups are not adjacent, N-C1-C6-alkyl-N,N-di(C4-C10-alkane carboxylic acid)amine, 1,4-piperazine-di(C1-C10-alkane carboxylic acid), and a process for producing these filaments, their use for the production of fibers and flat products, and fibers and flat products made of these filaments.

Description

a ... ~~~r~~~~r D. Z . 0050/43295 HIGH SPEED SPUN FILAMENT YARNS EASED ON POLYCAPROLACTAM
AND PRODUCTION THEREOF
The present invention relates to filament yarns having a relative viscosity RV of from 2.0 to 3.0 (measured at a concentration of 1 g of yarn per 100 ml in 96$ strength by weight sulfuric acid) based on polycapro-lactam, obtainable by (a) extruding a melt consisting essentially of poly caprolactam through a spinneret to form polycapro lactam filaments, (b) cooling the filaments thus produced, and (c) taking off the cooled filaments at a speed of at least (3600 + 1250 x (3.0 - RV)] m/min, wherein the polycaprolactam used was prepared in the.
presence of at least one dicarboxylic acid selected from the group consisting of C,-Clo-alkanedicarboxylic acids, - C5-C8-cycloalkanedicarboxylic acids, - benzene- and naphthalene-dicarboxylic acids which may carry up to two sulfonic acid groups and whose carboxylic acid groups are not adjacent to each other, - N-Cl-C~-alkyl-N,N-di(C,-Clo-alkanecarboxylic acid)-amine, - 1,4-piperazinedi(C,,-Clo-alkanecarboxylic acid).
The present invention further relates to a process ~~or producing these yarns, to the use thereof for manufa$turing sheetlike structures, and to sheetlike structures from these yarns.
In the high speed spinning of polyamides, the filaments emerging from the spinneret are in general taken off from the face of the spinneret at speeds of above 3000 m/min, while in conventional spinning the takeoff speeds a're in general not more than about 1200 m/min.
Compared with conventional spinning, high speed a 2 _ O.Z. 0050/43295 spinning generally offers the advantage of higher pro-ductivity. In some cases, especially in the case of polycaprolactam, the operation of drawing can be dis-pensed with in certain circumstances . A further advantage of high speed spinning is that the spinning and winding are in general less affected by the moisture content and temperature of the ambient air than in conventional spinning. Furthermore, the storability of the wound-up yarns until required for further processing is in general improved compared with conventionally spun yarns. More-over, high speed spun filament yarns are in general particularly useful for draw-texturing, draw-warping and draw-sizing.
Draw-texturing comprises drawing and texturing in one operation, the effect of texturing being to create.
a special fiber structure through direction-specific orientation of the macromolecules. This generally results in higher elasticity, bulk and thermal insulation com pared with flat yarns. For improved further processing such yarns can be subsequently oiled and/or intermingled.
The manufacture of warg-knitted or woven material requires a multiplicity of yarns being fed side by side in a parallel arrangement as a warp into the warp knittin or weaving machine. For this purpose several g hundred to several thousand -yarns are wound together onto a beam. In the course of being beamed the yarns are frequently intermingled, reoiled, paraff inated or sized to imprpve their compaction and further processing. A
plurality of such beams can be combined in a further operation to increase the number of yarns. The production ' beam can be combined with a conjoint of a. ( partial ) warp drawing of the entir~ yarn sheet (draw-warping) or similarly with sizing of the yarn sheet (draw-si.xing), in which the yarns are coated with a nixing agent to improve their running Properties and their mechanical integrity.
. Similarly, the drawing step can be carried out in a conventional manner inanediately following spinning or o.
r ..:

- 3 - O.Z. 0050/43295 in-line therewith.
EP-B-201 139 describes a melt spinning process for producing polyamide filaments, characterized in that a molten polymer mixture which contains a low molecular weight additive such as water and has a relative viscos-ity of from 2.0 to 3.0 (measured in 96$ by weight sul-furic acid) is extruded, the filaments formed are cooled, and the cold filaments are taken off at a speed of more than 3200 m/min. Yarns from polycaprolactam prepared in the presence of a dicarboxylic acid acting as chain regulator are not described.
DE-A-4,019,780 describes a process for producing polycaprolactam in the presence of dicarboxylic acid ' chain regulators. Yarns spun at the high takeoff speed of 4250~m/min from the polycaprolactam described therein.
(relative viscosx.ty RV = 2.36) proved to be comparable to prior art yarns in breaking strength and breaking exten-sion.
A disadvantage of high speed spun yarns and of drawn or draw-textured yarns obtained therefrom is that in general they have lower tenacities at break than conventionally spun yarns drawn or textured to the same extension at break. Furthermore, the stress-strain (force-elongation) curve of high speed spun yarns is in general too flat.
Compared with high speed spun nylon-6,6 (poly hexamethyleneadipamide), furthermore, high speed spun polycapzclactam yarns have after draw-texturing to the same extension at break the disadvantage of a lower crimp stability.
' It is' an object of the present invention to make available high speed spun filament yarns based on poly-caprolactam that are free of the abovementioned dis-advantages. More particularly, the yarns shall have a steeper stress-strain curve, an improved tenacity at break and - in the case of. textured yarns - an improved crimp stability.

:~.',0. Z . 0050/4325 We have found that this object is achieved by the _filament yarns defined at the beginning.
We have also found a process for producing these yarns, a use thereof for manufacturing sheetlike struc tares, and sheetlike structures from these yarns.
The invention proposes spinning a melt consisting essentially of the above-defined polyeaprolactam and taking off the cold filaments at a speed of at least [3600 + 1250 x (3.0 - RV)] m/min, preferably of at least [3800 + 1250 x (3.0 - RV)] m/min. Spinning speeds of greater than [3600 + 1250 x (3.0 - RV)] mlmin axe found to give an unexpected improvement in the tenacity. This is evident from the fact that the higher the spinning ' speed above [3600 + 1250 x (3.0 - RV)] m/min for a given RV, the greater the increase in the tenacity of the.
resulting spun yarns. Commercial polycaprolactam does not to the best of our knowledge show this effect to any significant extent, if at all (see comparative examples).
Again, from observations to date, the effect does not occur below a spinning speed of [3600 + 1250 x (3.0 - RV)] m/min for a given RV.
The upper limit for the spinning speed is in general not higher than 8000 m/min and depends essentially on the viscosity of the melt to be spun and on the spinning apparatus used.
The relative viscosity RV of the polycaprolactam to be spun is in general within the range from 2.0 to 3.0 (measured' at a concentration of 1 g of the polycapro-lactam'per 100 ml of 96% strength by weight of sulfuric acid at 25°C), preferably within the range from 2.3 to 2.9. A polycaprolactam having an RV greater than 3.0 is in general too viscous for high speed spinning, while a polycaprolactam having an RV less than 2.0 does not in general give stable filaments.
According to the invention, the relative viscos-ity RV of the spun filaments is within the range from 2.0 to 3.0 (measured at a concentration of 1 g of filament - 5 - O.Z. 0050/43295 per 1Q0 ml in 96~ strength by weight of sulfuric acid at _25°C),.preferably within the range from 2.3 to 2.9.
The polycaprolactams used according to the invention are prepared in the presence of at least one ~ dicarboxylic acid chain regulator. polycaprolactams of this type are known for example from US-A-3,386,976 and DE-A-40 19 ?80. The polycaprolactams of the invention are preferably prepared on the lines of the single-stage process described in DE-A-40 19 780.
Using a dicarboxylic acid chain regulator it is advantageous for the caprolactam to be polymerized at from 230 to 300°C, preferably at from 240 to 290°C, in the presence of water as initiator.
Suitable apparatus for carrying out the polymer ization is known to the person skilled in the art and.
described for example in DE-B-2,448,100, DE-B-1,495,198 and EP-B-20,946.
The water used as initiator is in general used in an amount of from 0.1 to 5$ by weight, in particular of from 0.5 to 3$ by weight, based on caprolactam.
The dicarboxylic acid used is preferably of the type which acts as a difunctional chain regulator in the hydrolytic polymerization of caprolactaan and does not decompose under the conditions of the polymerization and of spinning or lead to discolorations or other undesir-able phenomena. Furthermore, the dicarboxylic acid used must not for example have a chain limiting effect due to the formation of a ring structure. Examples of dicar-boxylic acids that are unsuitable are succinic acid and phthalic acid, since they may have a chain limiting effect due to ring closure.
Examples of suitable dicarboxylic acids are Cd-Clo-alkanedicarboxylic acids such as adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid and dodecanedioic acid, preferably adipic acid, C~-C8-cycloalkanedicarboxylic acids such as - 6 - O.Z. 0050/43295 cyclogentane-1,3-dicarboxylic acid and cyclohexane-1,4-dicarboxylic acid, preferably cyclohexane-1,4-dicarboxylic acid, ~

may benzene- and naphthalene-dicarboxylic acids which carry up to two sulfonic acid groups, or alkali metal salts thereof, and whose carboxylic acid groups are not adjacent to each other, such as terephthalic acid, isophthalic acid, naphthalene-2,6-dicarboxylic acid and 5-sulfur-isophthalic acid, preferably terephthalic acid, isophthalic acid and 5-sulfur-isoghthalic acid, and mixtures thereof, N-C1-C6-alkyl-N, N-di ( Cd-Clo-alkanecarboxylic acid) amine such as N-methyl-N,N-di(caproic acid)amine and N-methyl-N, N-dl. ( aCetlC .acid) dnllne, 1,4-piperazinedi(C,,-C6-alkanecarboxylic acid) such as.

1,4-piperazinediacetic acid, 1,4-piperazinedipropionic acid, 1,4-piperazinedibutanoic acid, 1,4-piperazinedi-pentanoic acid, and 1,4-piperazinedihexanoic acid, preferably 1, 4-pip~erazined3.acetic acid, 1, 4-piperazinedi-propionic acid.

Filaments containing dicarboxylic acids with tertiary amino groups are in general readily dyeable with anionic dyes. In some cases this can be desirable if particularly deep colors; are to be achieved.

Filaments that contain sulfonate groups are in general readily dyeable with cationic dyes but less receptive to anionic dyes, which occur for example in many foods and beverages, which in general results in reduced staining.

~ ~ The dicarboxylic acid is in general added at the ' top of the polymerization zone, from where it is thoroughly mixed in with the melt to be polymerized.

However, the dicarboxylic acid can also be added before or during the polymerization.

The amount of dicarboxylic acid used is in general from 0.05 to. 0.6, in particular from 0.1 to 0.5, mol%, based on caprolactam.

~1.~'~3~5 - 7 - O.Z. 0050/43295 In a further embodiment, designed to improve the anionic dyeability, the dicarboxylic acid chain regulator is combined with a diamine chain regulator of the type N, N=di ( C1-C6-alkyl ) amino ( CZ-Clz-alkyl ) amine .
Examples are 2-diethylamino-1-ethylamine, 6-dimethylamino-1-hexylamine, 3-dimethylamino-1-propyl-amine, 3-diethylamino-1-propylamine, preferably 3-dimethylamino-1-propylamine, 3-diethylamino-1-propyl-amine.
Preference is given to using the diamines of type N, N-di ( C1-C6-alkyl ) amino ( CZ-C,Z-alkyl ) amine in amounts of from 0.05 to 0.3, in particular preferably from 0.1 to 0.3, mol%, based on caprolactam. The use of less than - 0.05 mol% does not in general lead to any significant improvement in dyeability, while if the amount is above 0.3 mol% the chain limiting effect of these amines will in general become excessive.
In another embodiment, primary monoamines can be used alongside the dicarboxylic acid chain regulators mentioned, if a reduction in the carboxyl group content and an improvement in the melt stability of the product are desired.
Suitable primary monoamines are Cd-C,2-alkylamines and C6-aryl-C1-C,-alkylamines such as butyl-, pentyl-, hexyl-, heptyl-, octyl-, nonyl-, decyl-, undecyl- and dodecyl-amine and phenylmethyl-, phenylethyl-, phenylpropyl- and phenylbutyl-amine, preferably hexylamin~,-octylamine, decylamine and phenylethylamine.
The primary monoamines are preferably used within the range from 0.05 to 0.5 mot%, particularly preferably ' from 0.l to 0.4 mol%, based on caprolactam.
The polymerization can in general be carried out at a pressure within the range from 100 to 2000 kPa. A
particularly preferred embodiment comprises carrying out the polymerization continuously under a uniform pressure of from 100 to 190, preferably of from 100 to 170, kPa, measured in the vapor phase above the polymerization ~ .-~. r...~ r~ P' A . :ofr~.2..~ S'~ ~'~
- 8 - ~.Z. 0050/43295 zone, while maintaining a water content of from 0.1 to 0.5, in particular from 0.1 to 0.4, % by weight in the melt. It will be understood that the excess water intro-duced at the top into the reaction zone is continuously distilled off as a function of the pressure employed in order to maintain the aforementioned water content.
The polymerization time is in general from 5 to 20, preferably 8 to 12, hours and depends essentially on the properties desired for the product.
The polycaprolactam is advantageously removed from the polymerization zone at the lower end thereof.
The level of chemically bound dicarboxylic acid (determinable by hydrolysis of the polycaprolactam and subsequent analysis) in the extracted and dried end product is in general within the range from 5 to.
60 mmol/kg, preferably within the range from 10 to 50 mmol/kg. Values below 5 mmol/kg do not in general bring the desired improvement in the properties of the.
high speed spun yarns. Values above 60 mmol/kg do not in general make it .possible to obtain the relative viscosity/molecular weight desired for preparing the polymer.
If the end product additionally contains chemic-ally bound diamines, the level thereof is in general within the range from 5 to 30 ma~aollkg, preferably from 10 to 30 manol/kg, in which case the level of chemically bound dicarboxylic acids will in general be within the range f~,om 10 to 50, preferably from 15 to 50, nunol/kg.
-~ The level of water-extractable residual monomers and oligomers in the ready-to-spin polycaprolactam is ' chosen to be within the range from 0 to 2, preferably from 0 to l, % by weight of the polycaprolactam.
The water content of the ready-to-spin poly caprolactam is in general within the range below 0.4, preferably from 0.02 to 0.15, % by weight.
The unintermingled filament yarns of the inven-tion generally have an extension at break within the _ g _ O.Z. 0050/43295 range~from 30 to 100, preferably from 40 to 90$. By intermingling it is possible if desired to reduce the extension at break still further.
The polycaprolactam to be spun and the filaments obtained therefrom may contain customary additives and processing aids. The proportion thereof is in general up to 5, preferably up to 3, ~ by weight, based on the total weight of the polycaprolactam.
Customary additives are for example antioxidants, thermal stabilizers, W absorbers, dyes, pigments, delusterants and antistats.
Antioxidants and thermal stabilizers are for example sterically hindered phenols, hydroc~uinones, - phosphites and derivatives and substituted representatives of this group and mixtures thereof, and.
also copper compounds such as copper(I) iodide and copper(II) acetate.
Examples of W stabilizers are substituted resorcinols, salicylates, benzotriazoles and benzo phenones, which in general are usable in amounts of up to 1% by weighty here it is also possible to use manganese(TI).
Suitable colorants are organic dyes and the customary spin-dyeing agents such as chromium or copper complexes, inorganic pigments such as titanium dioxide and cadmium sulfide, iron oxides or pigment grade carbon black.
~ antistats it is possible to use the customary substas'fces, for example polyalkylene oxides and deriva tines thereof.
' The addition of the additives can take place at any stage of the manufacture of the filament yarns of the invention, but it is advantageous to add the stabilizers early in order to achieve stabilization sight from the beginning. Accordingly, the stabilizers are in general added even during the polymerization process, provided they do not interfere therewith.

- 10 - O.Z. 0050/43295 The filament yarns of the invention can if desired be drawn, draw-twisted, draw-wound, draw-warped, draw-sized and draw-textured in a conventional manner.
The drawing to a flat yarn can be carried out in one operation with the high speed spinning process, producing fully drawn yarn, FDY, or fully oriented yarn, FOY, or in a separate operation. Draw-warping, draw-sizing and draw-texturing are in general carried out separately from the high speed spinning process.
The filaments of the invention can be processed into fibers in a conventional manner. Sheetlike struc-tures can be manufactured for example by weaving or knitting.
The high speed spun yarns of the invention are advantageous over the prior art,yarns in possessing an.
improved tenacity, a steeper stress-strain curve and an improved crimp stability. Furthermore, from experience to date, yarns of the invention have fewer drawing defects than the prior art high speed spun polycaprolactam yarns .
Further studies have shown that the polycapro-lactam used according to the invention has a reduced melt elasticity and develops a special crystal morphology on fiber formation. The improved properties of the yarns according to the invention may be presumed to be con-nected with the special elasticity of the polymer melt and the special morphology of the filaments.
EXAMPLES
~The polycaprolactam was produced using a precon-densat~on tube having a mechanically agitated first reaction zone as described in EP-A-20,946. The precon-densation tube had a capacity of 340 1 and was heated with a heat transfer fluid.
The relative viscosity RV of~the polycaprolactam and of the spun filaments was determined at a concentra tion of 1 g per 100 ml in 96% strength by weight sulfuric acid at 25°C.
The residual moisture content was determined by ~~,.~"~3'~~
- 11 - O.Z. 0050/43295 the vapor pressure method using an Ackermann instrument.
The levels of chemically bound dicarboxylic acid and of chemically bound diamine are known from the starting quantities. The levels can also be determined by hydrolyzing the polycaprolactam in dilute mineral acid and then analyzing the mixture thus obtained.
To characterize the melt elasticity of the polycaprolactam, the elastic compliance Je, determined under oscillatory shearing, of the samples regulated according to the invention with dicarboxylic acid was referred to the compliance J~,r~t of standard products of the wane viscosity regulated with propionic acid.
_ The measurements were carried out on an RUS2 Rheometrics dynamic spectrometer using a plate-plate arrangement radius 25 mm, distance ~. mm) at 250~C and a.
shear amplitude of 0.3. The quantities measured were the storage modules G' and the loss modules G" for circular frequencies of from 0.3 rad/sec to 100 rad/sec. The measured curve was marked at that circular frequency at ~20 which the loss modules had just reached the value G"=103 Pa. From the corresponding storage modules G' the compliance is given by equation 1 as Je ~ G./~G,.)2 a G~/106 Pa2 ~eq~ 1) The reference compliance J~,s~t f or the propionic acid regulated product of the same viscosity was deter-mined in~the same way. Finally, the two compliances were expressed as a ratio R (equation 2) a _ _ R = J"/Js,rsi (eq. 2) to derive a rheological parameter for the melt elasticity that permits detection of differences in the elasticity of the melt with a very high resolution.
The breaking extension was determined using an Llster Tensorapid I instrument in which the clamped length - 12 - O.Z. 0050/43295 was 2Q0 mm in the case of partially, oriented yarn (POY) and 500 mm in the case of drawn and textured yarns. The time to break the yarns was of the order 20 t 2 seconds.
The pretensioning force was 0.025 cN/dtex in the case of POY, 0.05 cN/dtex in the case of drawn yarn and 0.2 cN/dtex in the case of textured yarn.
The breaking tenacity R$ was determined according to equation 3 R$ = F$/Tt" ( eq. 3 ) -where Fx is the ultimate tensile strength [cN] and Tt" the original linear density [dtex]. The value employed for the ultimate tensile strength was the highest value recorded in the breaking extension measurements.
The breaking extension E$ was expressed as the ratio of the elongation oL at break to the original length 1" of the specimen, according to equation 4:
E$ = of x 100%/1,, (eq.4) where of is the difference between the length of the specimen at break, 1g, and the original length 1".
These determinations were also recorded in graph form as stress-strain or force-elongation diagrams.
The warping defects were determined at a warping speed of 600 m/min using a hindley Standard Yarn InspectQr.~series 1900.
'~ The crimp contraction, the crimp modulus and the crimp stability of the textured yarns were all determined in accordance with DIN 53 840.
In a few selected cases the morphology of the spun filaments was characterized by X-ray small angle scattering (XSAS). The XSAS measurements were carried out in a pre-evacuated Kiessig chamber. The apertures in the collimator tube were 0.4 and 0.3 aun in diameter, and the distance A between the fiber specimen and the flat ~L-ray - 13 - O.Z. 0050/43295 film ,(AGFA-GEAAERT, Osray M3) was 400 mm. The X-ray source used was a Cu tube, operated at 37 kv and 36 mA, whose R« line (wavelength a =0.15418 nm) was selected for the measurements by means of a graphite primary mono-chromator. By way of sample preparation for XSAS analysi-s, th.e partially oriented yarn was wound on a frame with the individual filaments inexactly parallel arrangement.
The fiber bundles from 0.7 to 1 mm in thickness were subjected to a perpendicular X-ray beam with the fiber axis in a vertical position. The exposure time was 20 or 40 h.
The meridian reflections of the XSAS films due to the crystalline-amorphous superlattice of the POY fila-ments was evaluated with the aid of a photometer (micro-densitometer 3CS from Joyce Loebl). More specifically,.
the meridian reflections were scanned along the parallel to the film equator running through the meridian maximum using a gray wedge of optical density D = 0.95. The full width at half maximum (FWF~i) of the resulting photometer curve is a measure. of the thickness Ag of the crystal Fibrils perpendicular to the fiber axis. The lateral crystal thickness ng can be approximated as follows:
A~ = L ( nm) /B ( rad) ( eq. 5 ) where a is the X-ray wavelength and Brad) is the half-value width of the photometer curve measured in radian.
B ( rad ) ~~s obtained f ram the FWHM value F3 ( ~ ) by the equatibn:
.. _ _ Brad) - 8(mm)/A x F (eq~ 6) where A is the distance between fiber sample and X-ray film and F is the translation factor of the photometer.
Inserting A = 400 mm and F.= 5, equation 5 becomes nF ~ (J~ ( nm) / H (mm) J ~ 2 ~ 10 3 ( eq . 7 ) a ~~..~;" i °~'~
- 14 - O.Z. 0050/43295 The polycaprolactam was spun by melting in an extruder (Barmag 3E-24S, screw 38 mm in diameter, L/D=24) and forced through a spinning jet (hole count 12, hole diameter 0.20 mm, capillary length 0.40 mm). The result-s ing filament yarns were first passed through a quench cell (height 1600 mm, 0.4 m/sec transverse flow of air at 22°C and 65% relative humidity) and then through a free-fall cell (height 2000 mm), taken off on an EMS-Invents pilot spinning position via two pairs of godet rolls 150 mm in diameter, and wound up on an SW 46 1S-900 winder from Barmag.
The distance between jet and oiler was 1300 uua.
Drawing was carried out cold at 740 m/min on a drawtwister (J5/10a, Rieter).
Draw-texturing was carried out at 600 or 800 m/min on an FKS6L-10 draw-texturing machine from Barmag.
A. Preparation of golycaprolactam.

Molten caprolactam containing 0.5% by weight of water and 0.53% by weight of terephthalic acid as chain regulator was continuously fed with stirring under atmospheric pressure into the first reaction zone of the precondensation tube. The throughput was 25 kg/h. At the same time a mixture of 70% by weight of polycaprolactam (RA ~ 1.9) and 30% by weight of titanium dioxide (anatase form) was~a.ntroduced into the first polymerization zone at a 'rate of 225 g/h. The temperature of the first reaction zone was 252°C. The heat of polymerization evolved in the subsequent reaction zones was removed through appropriate cooling with internal heat exchangers . The temperature of the last reaction zone was 265°C.
After extraction with boiling water and sub-sequent drying, the product had a relative viscosity of 2.39, a (chemically bound) terephthalic acid content of .
- 15 - ~.Z. 0050/43295 36 mmol/kg, a residual moisture content .of from 0 . 046% by weight and a titanium dioxide content of 0.3% by weight.
~The elastic compliance Je was 8.3 x 10°6 Pa-1 and the relative index R was 0.78.

Caprolactam was polymerized by the method of Example 1 using 0.80% by weight of terephthalic acid as chain regulator. The throughput was 30 kg/h and the rate of addition of the titanium dioxide mixture was 270 g/h.
The other experimental conditions of Example 1 were retained.
The product had a relative viscosity of 2.32 and a (chemically bound) terephthalic acid content of 54 mmol/kg, The elastic compliance J~ was 5.1 x 10°6 Pa-1 and R was 0.48.~The titanium dioxide content was 0.3% by weight and the residual moisture content was 0.016% by weight.

Caprolactam having a water content of 0.7% by weight was polymerized by the method of Example 1 under a gauge pressure of 30 kPa using 0.21% by weight of terephthalic acid as chain regulator. The throughput was 34 kg/h: The temperature of the first reaction zone was set to 240°C. No titanium dioxide was added.
The product had a relative viscosity of 2.71 and a (chemically bound) terephthalic acid content of 14 mmol/kg. The residual moisture content was 0.019% by w~ight.

3p ~ ~ Caprolactam having a water content of 0.6% by weight was polymerised by the method of Example 3 using 0.29% by weight of terephthalic acid as chain regulator.
The temperature of the first reaction zone was set to 245°C. The other experimental conditions of Example 3 were retained. No titanium dioxide was added.
The product had a relativ~ viscosity of 2.71 and a (chemically bound) terephthalic acid content of ~~.3'~3'~~
- 16 ° p.Z. 0050/43295 19 mmol/kg. The residual moisture content was 0.021 by weight .
EXAMPLE 5a Caprolactam having a water content of 0.6% by weight was polymerized by the method of Example 3 using 0.37$ by weight of terephthalic acid as chain regulator.

The temperature of the first reaction zone was set to 251C. The other experimental conditions of Example 3 were retained. No titanium dioxide was added.

The product had a relative viscosity of 2.6? and a (chemically bound) terephthalic acid content of 25 mmol/kg. The residual moisture content was 0.091% by weight.

EXAMPLE 5b Caprolactam containing 0.5% by weight of water and 0.26% by weight of adipic acid as a chain regulator was polymerized by , the method of Example 3. The throughput was 35 kg/h. The temperature of the first reaction zone was set to 250C. No titanium dioxide .was added. , The product had a relative viscosity of 2.6'7 and a (chemically bound) adipic acid content of 20 mmol/kg.

The residual moisture content was 0.018% by weight.

EXAMPLE 5c Caprolactam was polymerized in the presence of 0.5% by weight of water, 0.81% by weight of the lithium salt of 5-sulfoisophthalic acid as a chain regulator and 0.18% by-laeight of titanium dioxide. After extraction with boiling water and subsequent drying the product had a relat~.ve viscosity of 2.55, a titanium dioxide content of 0.20% by weight and a residual moisture content of 0.031% by weight.

B. sigh speed spinning of polycaprolactam The polycaprolactam prepared in Example 1 was spun from the melt at 265°C at (a) 4500 m/min and (b) 5500 m/min. The RV of the yarn was 2.48. The as-spun - 17 ~ O.Z. 0050/43295 linear density was in case (a) dtex 50 f 12 and in case (b) dtex-41 f 12. After drawing the yarns spun at 4500 m/min had a linear density of dtex 44 f 12.
Table 1 shows the results.

The run of Example 6 was repeated with a commer-cial polycaprolactam (chain regulator: propionic acid, content in product - 40 mmol/kg, RV = 2.37, titanium dioxide - 0.3~ by weight, elastic compliance 11.5 x 10'6 Pa'1, residual moisture content 0.044 by weight) under otherwise identical conditions.
Table 1 shows the results.

The polycaprolactam prepared in Example 2 was spun from the melt at 265°C at (a) 5500 m/min and (b) 6000 m/min. The RV of the yarn was 2.31. The as-spun linear density was ( a ). dtex 42 f 12 and ( b ) dtex 43 f 12 .
Table 2 shows the results.

The run of Example 7 was repeated with the same commercial polycaprolactam of Comparative Example 1 under otherwise identical conditions.
Table 2 shows the results.
EXAMPhE 8 The polycaprolactam prepared in Example 3 was spun from the melt at 275°C at (a) 4500 m/min, (b) 5500 m/min and (c) 6000 m/min. The RV of the yarn was 2.79. The:as-spun linear density was (a) dtex 54 f 12, (b~ dte~'S1 f 12 and (c) dtex 52 f 12. The as-drawn lineal -density was dtex 45 f 12 in the case of the spinning speed of 4500 m/min.
Table 3 shows the results.

..,v.:.w::-::~.,.,,. r..v:... .. . ~, ~ .
- 18 - O.Z. 0050/43295 The run of Example 8 was repeated with a commer-vial polycaprolactam (chain regulators propionic acid, content in product - 20 mmol/kg, RV = 2.68, elastic compliance 10.0 x 10-6 Pal, residual moisture content 0.012% by weight) under otherwise identical conditions.
Table 3 shows the results.

The polycaprolactam prepared in Example 4 was spun from the melt at 275°C at 4500 m/min. The RV of the yarn was 2.83. The as-spun linear density was dtex S 4 f 12 . The yarn was then draw-textured at ~i 0 Om/min on a draw-texturing machine ( Barmag FK 6L-10 ) at <3 heater temperature of 180°C with a D:Y ratio of 2.33 to HE yarn (disk combination and arrangement: Ceratex all-ceramic.
disks arranged 1:5:1).
Table 4 shows the results.

The run of Example 9 was repeated with, the commercial polycaprolactam of Comparative Example 3 (residual moisture content 0.017% by weight) under otherwise identical conditions.
Table 4 shows the results.

The polycaprolactam prepared in Example 5a was spun from the melt at 275°C at 5500 m/min. The RV of the yarn was 2.69. The as-spun linear density was dtex 5 4 :~. ~ 12 .
w Table 5 shows the results.
~ COMPARATIVE E~~AMPLE 5 The run of Example 10 was repeated with a comnner-cial polycaprolactam (chain regulator: propionic acid, content in product - 20 ~nol/kg, RV = 2.66, elastic compliance 10.0 x 10°6 Pa'1, residual moisture content 0.098% by weight) under otherwise identical conditions.
Table 5 shows the results.

,-- 19 - 0>Z. 0050/43295 '- A polycaprolactam prepared analogously to Example 5a (0.37$ by weight of terephthalic acid as chain regu-lator, relative viscosity 2.67, chemically bound tere-phthalic acid content of end product 25 mmol/kg, residual moisture content 0.02 by weight) was spun from the melt at 275°C at 4500 mlmin. The RV of the yarn was 2.78. The as-spun linear density was dtex 54 f 12. The yarn was then draw-textured at 800 m/min on a draw-texturing machine ( from Barmag, FR6L-10 ) using a heater temperature of 180°C, a Ceratex disk combination 1:5:1 and a D:Y
ratio of 2.2.
Table 6 shows the results.
_ COMPARATIVE EXAMPLE 6 The run of Example 11 was repeated with a com-.
mercial polycaprolactam (chain regulator: propionic acid, content in product - 20 mmol/kg, RV ~ 2.68, residual moisture content 0.017% by weight) under otherwise identical conditions.
Table 6 shows the results.
CO1~ARATIVE EXAMPLE 7 (analogously to DE-A-40 19 780) Polycaprolactam prepared analogously to Example 4 of DE-A-40 19 780 with a relative viscosity of 2.36, a titanium dioxide content of 0.03% by weight and a residual moisture content of 0.04% by weight was melted at 269°C in an extruder (Barmag 3E, 3-zone screw 30 mm in diameter with LTM ( low temperature mixing) , L/D = 24 ) and forced i~hrough a jet (13 holes, hole diameter 0.20 mm, capilla3ry length 0.40 mm) . The filaments were then cooled down in a quench cell ( length 1500 mm, transverse quench) with air at 24°C and 40% relative humidity and then passed through a free-fall cell of 2200 nun in length to windup.
Windup took place without godets using a winding head ~rom Barmag (SW46 SSD) at 4250 m/min. The as-spun linear density was dtex 56 f 13.
The distance between jet and oiler was 1300 aim.

~..3'~~"75 - 20 - O.Z. 0050/43295 Drawing was carried out cold on a drawtwister (Rieter;_ J5/10a) at 605 m/min to an as-drawn linear density of dtex 44 f 13.
- Table 7 shows the results.

The run of Comparative Example 7 was repeated with commercial polycaprolactam (chain regulator: pro-pionic acid, content in product = 40 mmol/kg, RV = 2.36, titanium dioxide: 0.03%, residual moisture content: 0.04%
by weight) under otherwise identical conditions.

The polycaprolactam prepared in Example 5b was spun from a melt at 275°C at (a) 4500 m/min, (b) 5500 m/min and (c) 6'000 m/min. The RV of the yarn was 2.78. The as-spun linear density was dtex 53 f 12 in case (a), dtex 53 f 12 in case (b) and dtex 54 f 12 in case (c). After drawing the yarns obtained at a spinning speed of 4500 m/min had a linear density of dtex 44 f 12.
Table 8 shows the results.

The polycaprolactam prepared in Example 5c was spun from a melt at 275°C at (a) 4500 m/min, (b) 5500 m/min and (c) 6000 m/min. The RV of the yarn was 2.57. The as-spun linear density was dtex 54 f 12 in case ( a ) , dtex 54 f 12 in case ( b ) and dtex 55 f 12 in case (c). After drawing the yarns obtained at a spinning speed of 4500 m/min had a linear density of dtex 44 f 12.
Table 8 shows the results.

' - -The runs of Examples 12 and 13 were repeated with ' a commercial polycaprolactam (chain regulator: propionic acid, content in product ~ 20 mmol/kg, RV a 2.72, residual moisture content: 0.033% by weight) under otherwise identical conditions.
Table 8 shows the results.

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Claims (7)

We claim:

1. Filament yarns having a relative viscosity RV of from 2.0 to 3.0 (measured at a concentration of 1 g of yarn per 100 ml is 96% strength by weight sulfuric acid) based on polycaprolactam, obtainable by (a) extruding a melt consisting essentially of polycaprolactam through a spinneret to form polycaprolactam filaments, (b) cooling the filaments thus produced, and (c) taking off the cooled filaments at a speed of at least [3600 + 1250 x (3.0 - RV)] m/min, with the proviso that the polycaprolactam used was prepared in the presence of at least one dicarboxylic acid selected from the group consisting of - C4-C10-alkanedicarboxylic acids, - C5-C8-cycloalkanedicarboxylic acids, - benzene- and naphthalene-dicarboxylic acids which may carry up to two sulfonic acid groups and whose carboxylic acid groups are not adjacent to each other, - N-C1-C6-alkyl-N,N-di(C4-C10-alkanecarboxylic acid)-amine, - 1,4-piperazinedi(C1-C10-alkanecarboxylic acid).

2. Filament yarns as claimed is claim 1, wherein the polycaprolactam was prepared in the presence of at least one N,N-di(C1-C6-alkyl)amino(C2-C12-alkyl) amine.

3. Filament yarns as claimed in claim 1 or 2, having a breaking extension of at most 100%.

4. A process for producing filament yarns having a relative viscosity RV of from 2.0 to 3.0 (measured at a concentration of 1 g of yarn per 100 ml is 96% strength by weight sulfuric acid) based on polycaprolactam as claimed in claim 1 by (a) extruding a melt consisting essentially of polycaprolactam through a spinneret to form polycaprolactam filaments, (b) cooling the filaments thus produced, and (c) taking off the cooled filaments at a speed of at least [3600 + 1250 x (3.0 - RV)] m/min, with the proviso that the polycaprolactam used was prepared in the presence of at least one dicarboxylic acid selected from the group consisting of - C4-C10-alkanedicarboxylic acids, - C5-C~-cycloalkanedicarboxylic acids, - benzene- and naphthalene-dicarboxylic acids which may carry up to two sulfonic acid groups and whose carboxylic acid groups are not adjacent to each other, - N-C1-C6-alkyl-N,N-di(C4-C10-alkanecarboxylic acid)- amine, - 1,4-piperazinedi(C1-C10-alkanecarboxylic acid).

5. A process for producing filament yarns based on polycaprolactam as claimed in claim 4, wherein the polycaprolactam was prepared in the presence of at least one N,N-di(C1-C6-alkyl) amino (C2-C12-alkyl) amine or in the presence of at least one primary C4-C12-alkylamine or in the presence of at least one C6-aryl-C1-C4-alkylamine.

6. The use of the filament yarns of any of claims 1 to 5 for producing fibers and sheetlike structures.

7. The fibers and sheetlike structures of claim 6.