DE2119097A1 - Gatherable thread - Google Patents

Description

EGG. DU PONT DE NEMOURS AND COMPANY 10th and Market Streets, Wilmington, Delaware 19 898, V.St, A.

Frizzy thread

This invention relates to improved composite synthetic linear polyamides filaments.

Threads and yarns made from synthetic polyamides will be fine For many years it has been mainly used for the production of women's stockings. · There is currently an increased demand after so-called stretch stockings. Stockings of this type are much smaller than traditional stockings, but they have Ability to stretch much more, which on the one hand gives a better fit, and on the other hand for the normal ones Leg sizes are much less different stocking sizes Need to be kept in stock.

Composite yarns, are particularly suitable for the production of stretch stockings are described in US Patent 3,399,108. These threads are able to move under the influence

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of holding forces to pucker, and this leads to the distortion of the loops in the stocking fabric, so that the fabric has a stronger stretching capacity than conventional stocking fabrics. With this composite thread can While making good stretch stockings, there is a need for further improvements in gussability under the influence of exerted on the fabric Holding forces, especially when making miniature stretch stockings. In this context, the The widespread use of tights today also provides an improvement in the crimpability of multifilament Stocking hem yarns are very desirable. There is also a need to improve the thread strength to the Increase durability of stocking leg yarn.

The invention relates to a crimpable thread with two endless, eccentric components attached to one another, one of which consists of a homopolyamide and the other of a randomly structured copolyamide, characterized in that the randomly structured polyamide contains 70 to 82 percent by weight of BMS hexamethylene adipamide units 13 to 25 percent by weight of capxonamide units and 5 to 17 percent by weight of hexamethylendodecanedioic acid amide units.

Preferably, the thread is also characterized by a shrinkage under load (determined as described below) of less than 4 $ <*

Furthermore, the thread is preferably characterized by a Firmness naeli dsm decoction of at least 4.0 g / den.

The randomly structured polyamide is preferably characterized by an amide group frequency of 8440 to 8725 equivalents 10 g each and one by differential thermal analysis certain melting point of 210 to 225 ° C, both

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as described below ". The amide group frequency should be in this range, since the threads" have insufficient crimpability at a lower amide group frequency and an undesirable moisture sensitivity at a higher amide group frequency, which leads to a poor fit of the stockings at high humidity. The melting point determined by differential thermal analysis should not exceed 225 ° C. so that the copolyamide in the drawn thread has sufficient shrinkage capacity to achieve a high degree of crimp. But determined by differential thermal analysis melting point should be at least the other hand 21Q ⁰ C, to obtain a sufficient shrinkage stress for the curl under the action of clamping forces, and to ensure a high strength.

Preferably, the thread according to the invention is further characterized by a crimp elongation under load (determined as described below) of more than 30 $ , 2 mg / which is treated with water vapor at 100 ° C) is preferably less than 0.152 mm with a particularly preferred range of 0.076 "to 0.127 mm.

The homopolyamide is particularly preferably polyhexamethylene adipamide (Polyamide 6-6) or poly (ε-caprolactam) (polyamide 6), and the randomly structured copolyamide consists of 75 percent by weight of hexamethylene adipic anide units, 15 percent by weight of caproamide units and 10 percent by weight of hexamethylendodecanedioic acid amide units.

The threads according to the invention are made by spinning the Homopolyamide and the copolyamide side by side or as a sheath and core to form a thread (or several threads in the form of one

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Yarn), cooling and drawing the thread in conventional Way of passing the drawn yarn through a heating zone under low tension to develop a crimp, and then stretching the thread to remove the crimp. After passing through the heating zone the crimped thread should be allowed to cool before the crimp is removed. TJm the desired crimp properties To achieve this, the temperature in the heating zone should be at least 140 ° C. Set the required temperature depends of course on the length of the heating zone and the speed with which the thread is passed through the heating zone.

The preferred method of reducing the tension in the heating zone and then removing the crimp is to pass the pre-crimped thread over a series of stretching pins behind the stretching roller and insert a heating device, such as an air nozzle, between the stretching roller and the stretching pins, such as it is shown in Figures 1 and 4 of U.S. Patent No. 5,399,108. From the stretching pins, the thread runs around a force-fit driven roller, which rotates at a lower surface speed than the forging roller, so that the thread can contract between the two rollers _o The permissible degree of contraction depends on the amount of shrinkage, regardless of the crimp that takes place between the rollers. This in turn depends to a considerable extent on the temperature in the heating zone. In general, a high degree of stretching at the pins is desirable in order to achieve very low stress and maximum shrinkage in the heating zone.

Homopolyamide is formed when sheath-core threads are spun preferably the jacket in order to facilitate the cooling of the threads. When the copolyamide forms the sheath of the thread, it runs the cooling is slower and it can be done at high spinning speeds the threads stick together.

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The two thread components usually lie in the threads in approximately equal amounts of weight; however, the ratio can be changed as necessary to achieve the desired properties to achieve. In the case of sheath-core threads, it can be useful that the core has a slightly higher percentage of the contains more shrinking component.

In the manufacture of sheath-core threads, the core should be high grade eccentric in order to "develop the necessary retraction force when curling. This means that a part the coat is very thin; the minimum thickness of the sheath is in the range of 5 to 0.1 # or less of the total thread diameter.

Each of the two thread components can contain various additives commonly used in thread manufacture, such as matting agents, pigments, dyes, antioxidants, anti-static agents and Surface modifiers.

Yarns made from one or more composite threads according to the invention can be made from staple fibers or continuous filaments of various titers and yarn counts. Hosiery threads usually have a round cross-section; however, threads with other cross-sectional shapes can also be used, and these can even be used for certain purposes, such as knitted tricot fabrics or certain tissues, be particularly beneficial. For this purpose, for example, three-winged, shield-shaped, Use heart-shaped, cross-shaped or other multi-wing thread cross-sections.

The "relative viscosity" is the ratio of the outflow time an 8.2 weight percent polyamide solution at the outflow time of the pure solvent in a viscometer. The relative The viscosity is determined on solutions of 5.5 g of polyamide in 50 ml of 90 percent strength by weight formic acid at 25 ° C.

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Shrinkage and crimp elongation are determined as follows:

A strand of 750 denier of single or multi-ply yarn is made by winding the required number of turns on a spool. In the collapsed state, the strand has a length of 55 cm when it is loaded with a weight. The pus of the thread bundle, which represents the folded strand, is of course twice as high as that of the original strand, i.e. 1500 den. The strand is hung on a hook and a weight of 500 g hangs at the other end of the strand. After 1 minute, the length (a) of the strand is determined. Then the 500 g weight is removed and replaced by a weight of 1.8 g so that the strand is now under a tensile stress of 1.2 mg / den. This tension is slightly higher than that which is applied to the yarn during knitting. The strand with the attached weight is exposed to water vapor of atmospheric pressure at 100 C (hereinafter referred to as "atmospheric water vapor") for 1 minute, whereupon one the. Leave the strand on the air troola for 10 minutes. Then ri.M the length (b) of the strand geiaesFs & u Hereby we «! the 1 _S 8 g weight is exchanged for the 500 g weight, and after the latter is attached to the aero rope for 1 minute, the length (c) of the rope is determined. The extension and shrinkage of the thread are calculated according to the following equations

Ecäuseldehraaig, 2 & ~ 100 ^ f- shrinkage, f »- 100 ~ -

The Ireuseldurohmesser of the thread under a tension of 1.2 mg / den is determined indera one 25.4 mm long pieces of the crimped * tensioned strand with tape stuck on the slide of a microscope and enlarged it Image on a projection microscope

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screen covered with a line network.

The melting point of the polyamide becomes the same as that commercially available thermal analyzer "Du Pont 900" determined with the help of a calorimeter scanning head. Some devices are built to determine both endothermic (melting) and exothermic (freezing) temperatures; for those given here However, only the endothermic temperatures are used. Most polyamides, and especially copolyamides, melt within a temperature range that depends on the heating rate. In this determination the temperature maximum of the endothermic temperature diagram is taken as the melting point. Since polyamides usually do not have sharp melting points is the accuracy of this determination - 2 ° C, The polyamide sample can be in the form of flakes, chips, fibers or foils. In the following Examples are the polyamide samples in the form of flakes or fibers. According to the instructions for use of the above The Du Pont device performs the measurements under the following conditions:

Reference - aluminum pan Program mode = heating Heating speed = 12 ° C / min. Atmosphere = nitrogen, 6 min. T-scale = 50 ° C / 25.4 mm T-shift = 0
Δ T scale = 0.1 ° C / 25.4 mm Δ T shift =. 0

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RD-1760 β 2 ΐ 19097

The amide group frequency is calculated as follows: 1. Homopolyamides

a. AABB polyamides (e.g. polyhexamethylene adipamide

or r Polyhexamethylendodecandisäure- amide)

τ? - ² * ¹⁰

j, _

^w m. '
where P = amide group frequency,

W = molecular weight of the polyamide repeating unit in grams.

Therefore:

^P 6-6 ■ H ^ - - ⁸⁸⁵⁰

»6-12

b. AB polyamides (e.g. polycaprolactam)

m
Therefore:

m ⁶
P ₆ = ~~ = 8850 (the same value as for Polyhexa

'' 5 methyleneadipic acid amide) 2. Copolyamides

where f ^ the weight fraction of the polyamide 1 and P- mean whose amide group frequency, etc.

(Note: all copolyamides of caprolactam and hexamethylene adipamide have an amide group frequency Tone 8850). ,

So applies to 6-6 / 6 / 6-12 (75:15:10)

^{P = if} 6-6 ^{+ f} 6 ^{) 8850 + f} 6-12 ^{x 645} ° = 0.90 χ 8850 + 0.1Ox 6450

= 8610

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Example ΐ

An evaporator is charged with an aqueous solution of 116.6 kg of hexamethylenediammonium salt of dodecanedioic acid (6-12 polyamide salt), 922.6 kg of hexamethylenediammonium adipate (6-6 polyamide salt) and 153.3 kg of caprolaetam "and the solution at 3 , at heated 4, until the temperature of 146 ° E and the salt concentration of 76 $> is. Then, the solution is transferred into an autoclave, heated to 205 ° C and brought at a pressure of 18. at this point of the process, so much to 20 percent aqueous slurry of titanium dioxide, that the finished Gopolyamid contains 0.3 fi TiO ₂ as matting agent. Then, the solution at 18 to at heated to 230 ° C. Thereafter, the pressure is relaxed in the course of 80 minutes to atmospheric pressure, and the temperature is increased to 250 ° C. The copolyamide is then kept at atmospheric temperatures of 250 to 260 ° C. for 30 minutes and processed by extrusion at 7.1 atmospheres under nitrogen to form continuous strands which are cooled with water and cut into flakes. The copolyamide, which consists of 75 percent by weight of polyhexamethylene adipamide units, 15 percent by weight of poly-t-caproamide units and 10 percent by weight of polyhexamethylene dodecanedioamide units, has a relative viscosity of 46.

Conventionally, polyhexamethylene adipic acid arid flakes are made produced with a relative viscosity of 46.5. The two types of flakes (6-6 and 6-6 / 6 / 6-12) are used first conditioned in moist nitrogen at 125 ° C or 145 ° C and then melted and fed to a spinneret, as shown in FIG. 3 of US Pat. No. 3,399,108 is shown, with the holes arranged so that three-thread yarns are spun. After conditioning is the relative viscosity of the 6-6 polyamide 50 and that of the 6-6 / 6 / 6-12 polyamide 56. The two polyamides become with the copolyamide as the core to three-thread eccentric

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Sheath-core hosiery yarns spun up to 58 percent by weight from the randomly structured copolyamide and 42 percent by weight consist of the homopolyamide ". At its thinnest Place the sheath has a thickness that corresponds to about 1 # of the entire thread diameter knife. The distance between the Protrusion 135 and plate 142 according to US Pat. No. 3,399,108 is 0.076 mm. The threads are cooled in fixed in a 152 cm long duct at an air temperature of 60 ° C, then, as described in US Pat. No. 2,289,860, conditioned with steam and finally wound up at a speed of 500 m / min to form a package. Then the yarn is pulled from the package and attached to a non-heated stretching pin located between the feed roller and the rear roller is stretched to 4.47 times, so that it has a liter of 23-24 (nominally 20-3} den attained .. Then the thread runs from the forging roller at one speed of 533 m / min through a 3 inch tubular curling chamber of the type shown in Figure 5 of the United States patent 3 399 108 is shown. The yarn is made by passing 0.03 m ^ 278 ° G of leisser air per minute heated by the chamber »with the air at the chamber outlet has a temperature of 188 ° G.

The yarn then runs over two drawing pins, the total contact angle with the pins being 390 °, and then to a take-off roller and finally to a winder. The Yerstreekungsstifte slow down the thread of the yarn through the heating zone, so that the thread components shrink differently and the threads can be thinned under the influence of the heat, in addition, the yarn between the pins and the take-off roller is stretched so far that most of the crimp Will get removed. The yarn is allowed to contract by 40% of its drawn length between the forging roll and the take-off roll.

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1Q9346M640

911 BD-1760 ft ^L ' ^|

When the crimpable yarn is exposed to hot water or steam, it crimps back into very evenly, and the crimp diameter and the crimp elongation are quite even. The crimp stretch "at a load of 1.2 mg / den, determined as above is 38 # in atmospheric water vapor. The mean crimp distance and diameter are 0.56 mm and 0.12 mm, respectively. The shrinkage of the yarn is $ 1.6 .. The The strength of the yarn drawn from a finished stocking is 4.2 g / den.

Example 2

A 3-ply yarn produced according to Example 1 with a linear density of 20 den and a crimp elongation of 4-0 5 & is used as a Stocking leg yarn used for knitting women's stockings. to For comparison purposes, the same stockings are otherwise made from one 5-ply yarn of 20 denier knitted according to the last Paragraph of Example 3 has been produced. It is observed that the sock chair fabric from the yarn according to the Invention as it comes from the knitting machine, is much smaller than the comparison hosiery because the threads Show a tendency to pucker at this stage of the process. This reduction in size leads to a reduction in the formation of "picks" when the hosiery is processed in the factory. "Picks" are mistakes in the structure of the mesh. These may be minor distortions of the mesh that are can be eliminated by pulling a wale or a row of stitches, but it can also be a lot of distortion acts that are more difficult to fix. When the types of hosiery described above on their tendency to formation can be examined by "picks" by tumbling the sock stool for 6 minutes in a drum fitted with needle pins lined, which have the task of generating "picks" at high speed, are created in 12 stockings

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from the yarn according to the invention only 101 "picks", while in 12 stockings are made from the comparison hosiery 226 "Picks". Furthermore, it was found that the circulation steam treatment in the case of the hosiery made of the easily puckered yarn can be omitted entirely according to the invention, because a sufficient one is already found in the normal washing and dyeing processes Ripple forms. When hosiery made of the yarn according to the invention without prior circulation treatment with steam Washed for 15 minutes at 66 or 100 ° C and then dyed for 90 minutes at 82 ° G, the total length of the unshaped Stocking 48 cm and the length of the leg part 38 cm. The total mean length of the recirculation treatment with steam subjected to comparison stocking is 60 cm and the Leg length of the same 50 cm.

Example 3

Following the procedure of Example 1, copolyamide flakes are made produced, the 75 weight percent hexamethylene adipic acid units, 15 percent by weight of epsilon caproic acid amide units and 10 percent by weight of hexamethylene dodecanedioic acid amide units and have a relative viscosity of 55.9 *

The copolyamide flakes and polyhexamethylene adipic acid aroid flakes with a relative viscosity of 50.1 v / earth are spun from the spinneret described in Example 1 to form a sheath-core thread in which the copolyamide forms the core and which has a final denier of 15 denier . the existing of 60 weight percent Kern'und 40 weight percent sheath monofilament is cooled by air and wound up into a package. Then, the yarn is withdrawn from said yarn package and an unheated pin and a stretching roll at a order ^r peripheral speed of 776 m / min stretched 5.02 times. From the forging roll, the thread runs upwards through a tubular crimping caramer, as shown in FIG.

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Tentschrift 3 399 108 is shown, then a change of direction guide and down over a series of straightening pins with a diameter of 4.77 mm and a non-positively driven take-off roller that runs at a peripheral speed of 482 m / min revolves, to a winding device, where the thread in the usual way to the package is wound up. In the crimping device, the thread is heated by a stream of air that is heated from a temperature of 295 ° C Nozzle exits.

The threads identified in Table I rait A and B are marked with different degrees of stretching produced on the stretching pins. When making the thread B is the speed of the take-off roller is somewhat higher, which is noticeable in the lower degree of contraction. The cumulative angle of contact with the stretching pins, i.e. the sum of the contact angles with the individual extension pins is given in Table I. The frizz and The tensile strength properties of the threads can also be found in Table I.

For purposes of comparison, threads are produced in the same way as thread B, but with the difference that the thread core is made from a copolyamide, which according to Example VIII of US Pat. No. 3,399,108 by mixing a 49.5 percent by weight 6-6 polyamide salt solution, the 617.8 kg dry Contains salt, a 26% by weight 6-12 polyamide salt solution, which contains 220.5 kg of dry salt, and one 31 percent by weight 6-10 polyamide salt solution made with technical Sebacic acid and containing 377.8 kg of dry salt. The stretching ratio will be like this adjusted so that one obtains approximately the same elongation at break that the threads according to the invention also have. The air temperature in the Kräuselkamaer is slightly lower, since this lower temperature is closer to the optimum for the concerned

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Polyamide composition lies. These threads are labeled C and D in the table below.

0? away thread Hurry I. C. D. Stretching ratio A. B. 4.74 4.74 Pen stretching, cumu
lative contact angle 5.02 5.02 245 ° 1025 ° Contraction *, fo 245 ° 1025 ° 28 28 Air temperature at the
nozzle inlet s, ⁰ O 38 28 280 280 Crimp elongation, $> 295 295 41 63 Crimps per cm, stretched,
at 0.3 g / den load 58 71 11.2 16.4 Shrinkage, i ° 11.4 14.9 5.3 4.6 Crimp pitch, mm 3.0 3 * 7 0.648 0.371 Frill! Diameter, mm 0.565 0.384 0.200 0.112 strength, g / den 0.180 0.109 4 * 4 3.8 Elongation at break, $> 5.3 5.1 45 50 Firmness after the ab
cook, g / den 43 45 3.9 3.3 Elongation at break after the ab
cook, ^c / o 4.5 5.1 45 38 TDA melting point ** des
Copolyamides, ⁰ ° C 42 44 207 207 219 219

Amide group frequency des
Copolyamides ,, - equivalents per 10 ° g 8595 8598 7840 7840

* Contraction of the thread between the forging roller and the take-off roller, calculated from the circumferential speeds of the two rollers.

** Determined by differential thermal analysis.

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RD-1760 15

" Example 4

Seamless women's stockings are usually made from monofilaments of 15 knitted the same as threads 0, D and B of the example 3 have been produced. One notices that the stocking chair fabric as it comes from the knitting machine is in The case of threads D and B is much smaller than the hosiery made from threads C. In Table II the relative areas of the knitted hosiery indicated, with the area of the Socks made from thread C with a value of 1.00 is. This area reduction of the knitted fabric is due to the greater tendency of the threads D and B to move after the knitting to ripple. It is true that the relative area of the knitted fabric from the thread D is considerably reduced; but this comes at a cost a significant decrease in strength (by 0.6 g / den), as can be seen from a comparison of threads G and D in Table I. results.

Tabel B e i s ρ i e II 1 5 thread Relative area Area reduction C. 1.00 _ D. 0.35 65 B. 0.31 69

Following the procedure of Example 3, copolyamides are made from Hexamethylene adipic acid araid, epsilon caprolactam and hexamethylene dodecanedioic acid amide prepared with the compositions given in Table III and together with polyhexamethylene adipamide spun as a sheath component into two-component threads of 15 denier. The procedural conditions are the same as in Example 1. The crimp elongation for the three thread compositions results from Table III, the Compositions 75:15:10 and 70:20:10 as part of the invention

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dung, while the composition 82: 8: 10 is a comparison copolyamide represents.

Table III 6-6 / 6 / 6-12 copolyamide, wt .- ^

TDA melting point, ⁰ g

Amide group frequency, equivalents per 10 ° g

Crimp elongation, ° / °

75:15:10 70:20:10 82: 8: 10 219 215 * 234 * 8610 8610 8610 66 63 30th

* Determined from the phase diagram

The threads according to the invention and the yarns produced therefrom, which are explained in the preceding examples, show a good combination of advantageous crimping properties, high strength and low shrinkage in the textile fabric. Certain comparative polyamides, which are not within the scope of the invention, can be processed into threads which have almost the same characteristic crimp properties; However, this is only possible at the expense of strength, especially after boiling in the finished stocking. Furthermore, as the examples show, the threads according to the invention have the advantageous property that they are essentially straight after being removed from the package, but easily develop a crimp after knitting as a result of the mechanical processing of the thread in the knitting machine. This leads to a reduction in the area of the chair fabric and consequently to the formation of fewer "picks" in the stockings during processing in the factory. Furthermore, the shrinkage capacity of the yarns according to the invention, as the examples show is considerably lower than that of comparable of "two-hosiery yarns. These lower shrinkage (below $ 4>) of the threads according to the invention, the knitting allows denser Hosiery,

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which have less ^{tendency to form "picks 11} " and are more economical with regard to the amount of thread required for a certain stocking size Bicomponent thread for stretch stockings was required to produce satisfactory miniature hosiery.

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Claims (4)

EGG. du Pont de Nemours April 20, 1997I and Company RD-1760 claims 1. Gatherable thread with two endless, eccentric components, one of which is made from a homopolyamide and the other from a randomly thawed Copolyamide, characterized in that the randomly structured copolyamide is 70 to 82 percent by weight from hexamethylene adipic acid units, from 13 to 25 percent by weight from caproamide units and from 5 to 17 Percentage by weight consists of hexamethylendodecanedioic acid amide units. 2. Thread according to claim 1, characterized in that it has a shrinkage under load of less than 4 $> and a strength after boiling of at least 4.0 g / den. 3. Thread according to claim 1 or 2, characterized in that the randomly structured copolyaroid has a melting point of 210 to, determined by differential thermal analysis 225 C and an amide group frequency of 8440 to 8725 equivalents per 10 g. 4. Thread according to claim 1 to 3, characterized in that its crimp elongation under load is higher than $ 30. - 18 103846/1640 5. Use of threads according to claims 1 to 4 for production of hosiery. - 19 -109846/1640