EP0756026A1 - Process for manufacturing divisible thanelast-yarns - Google Patents

Abstract

A process for making divisible elastane multifilament yarns comprises a dry spinning process contg. the following steps :(1) at least one multi-hole spin nozzle is placed in the head of a standard dry spinning appts., the distance (x) between holes in the nozzle being >40 mm and <500 mm and the distance (y) between holes in adjacent nozzle plates is <500 mm but >(x) ; (2) turbulence is generated in the appts. by lamellar gas flow to bind the individual yarn filaments together as they leave the nozzle holes ; (3) the elastane yarns are passed out of a spin shaft via a first guide section contg. one hole per filament and then a second guide section to combine the filaments together to form a multifilament yarn ; and (4) the multifilament yarn is spooled-up. Elastane multifilament yarns made by this process are also claimed.

Description

The invention relates to a manufacturing process for divisible elastane multifilament yarns, which is carried out in such a way that coalescence of the individual filaments forming the yarn caused by fusing, gluing or mechanical intermingling or twisting is prevented. The single filaments that can be obtained from the process can be separated from the multifilament yarn bobbin after they have been removed and processed separately in textile production processes.

Elastane fibers are fibers that consist of at least 85% by weight segmented polyurethanes. These fibers achieve their typical property profile through the use of polyurethane polyureas made from oligomeric polyester or polyether diols, aromatic diisocyanates and short-chain aliphatic diamines. The thread is usually formed by spinning solutions of the polyurethanes by the wet spinning or preferably by the dry spinning process, polar solvents such as dimethyl sulfoxide, N-methylpyrrolidone, dimethylformamide or preferably dimethylacetamide being suitable as solvents in both cases.

Commercial elastane yarns have been known for a long time. Due to their elastic properties, they are used to manufacture functionalized textile products, i.e. Articles with a combination of elasticity and resilience or shape. For this purpose, the elastane filament yarn is refined with other inelastic yarns to form combination yarns, e.g. by winding, spinning or intermingling, or it is processed with the inelastic yarns directly to form a sheet material, e.g. by knitting or knitting.

To ensure that these processing processes run smoothly, the elastane yarns must be practically free of fluff, thin spots and defects. The prior art teaches that the elastane yarns are produced as coalesced multifilament yarns. This means that the individual filaments forming the total yarn are virtually in love with each other during their spinning, for example in the dry spinning process. A method for producing coalesced elastane yarns is described, for example, in US Pat. No. 3,094,374 and European Patent Application 182,615. In the former document, the The advantages of a multifilament with high interfilamentary adhesion with regard to safe processing are expressly described and methods for setting this property profile are disclosed.

It was therefore not to be expected that elastane multifilament yarns with good processing properties could be obtained even if the process for their production deliberately kept or avoided the interfilamentary adhesion.

Laid-open specification JP 03-059 112 describes bundled polyurethane multifilaments or monofilaments which are wound in an aligned manner on a spool, the bundled multi- or monofilaments having a separation tension of 15 mg or less when detached from the spool. They are processed as separate multifilaments or monofilaments at a speed of at least 150 m / min. These products are obtained by subjecting the filaments coming from the dry spinning apparatus to cooling to below 60 ° C. and adding a metal soap to the product. For the process according to JP 03-059 112, it does not matter whether multi or monofilaments are separated.

The object of the invention is the production of multifilament yarns which can be divided into their individual filaments when the bobbin is processed. These must not be twisted, swirled, or at one point or in love with each other longitudinally. It is important to find such rare, i.e. to completely prevent effects occurring at a distance of many hundreds of meters.

• 1) im Spinnkopf einer an sich bekannten Trockenspinn-Apparatur eine oder mehrere Mehrloch-Spinndüsen einsetzt, deren Einzelbohrungen auf einer Platte liegen, wobei der Abstand x der Bohrungen voneinander auf einer Platte und deren Abstand y zu Bohrungen auf benachbarten Mehrloch-Spinndüsen-Platten folgender Beziehung gehorcht:
  40 mm < x < y <500mm
• 2) in der Trockenspinn-Apparatur durch Laminarisierung der Spinngasströmung eine Verwirbelung der Einzelfilamente aus einer Mehrlochdüse bzw. aus benachbarten Mehrlochdüsen unterbindet,
• 3) nach dem Verlassen des Spinnschachtes die gebildeten Filament-Garne durch ein erstes Fadenleitorgan mit einer Öffnung pro Einzelfilament und danach durch ein zweites Fadenleitorgan führt, bei dem mehrere Einzelfilamente zu einem Multifilament zusammengefaßt werden und
• 4) das Multifilamentgarn aufwickelt.

The invention relates to a production process for the production of divisible, so-called splicable elastane multifilament yarns from known polyurethane polyureas with the aid of a modified dry spinning process, which is characterized in that

• 1) one or more multi-hole spinnerets are used in the spinning head of a dry spinning apparatus known per se, the individual bores of which lie on a plate, the distance x of the bores from one another on a plate and their distance y from bores on adjacent multi-hole spinneret plates following Relationship obeys:
  40mm <x <y <500mm
• 2) prevents turbulence in the individual filaments from a multi-hole nozzle or from adjacent multi-hole nozzles in the dry spinning apparatus by laminarizing the spinning gas flow,
• 3) after leaving the spinning shaft, the filament yarns formed through a first thread guide member with an opening per single filament and then through a second thread guide member in which several individual filaments are combined to form a multifilament and
• 4) the multifilament yarn is wound up.

The polyurea polyurethanes are produced by methods known per se. The synthetic structure of the fiber raw materials according to the prepolymer process has proven itself, with a long-chain diol in the solvent or in the melt being reacted with a diisocyanate to form a prepolymer in a first process step in such a way that the reaction product contains isocyanate end groups (NCO groups).

Polyester diols on the one hand and polyether diols on the other hand are preferred as long-chain diols. Mixtures of both types of diol are also suitable. These generally have a number average molecular weight of 1000-6000.

As polyester diols e.g. Suitable dicarboxylic acid polyester, which can contain both several different alcohols and different carboxylic acids. Mixed polyesters of adipic acid, hexanediol and neopentyl glycol in a molar ratio of 1: 0.7: 0.43 are particularly suitable. Suitable polyesters have a molecular weight of 1000-4000.

As polyether diols are, for. B. polytetramethylene oxide diols, preferably with a molecular weight of 1000-2000 (unless specifically mentioned, all molecular weights are understood as number average).

Polyester and / or polyether diols can also be used in combination with diols which contain tertiary amino groups. For example, are particularly suitable N-alkyl-N, N-bishydroxyalkylamines. The following are examples of connections:

4-tert-butyl-4-azaheptanediol-2,6,4-methyl-4-azaheptanediol-2,6,3-ethyl-3-azapentanediol-1,5,2-ethyl-2-dimethylaminoethyl-1,3 -propanediol, 4-tert-pentyl-4-azaheptanediol-1,6, 3-cyclohexyl-3-azapentanediol-1,5, 3-methyl-3-azapentanediol-1,5, 3-tert-butylmethyl-3 -azapentanediol-1,5 and 3-tert-pentyl-3-azapentanediol-1,5.

In the synthesis of the elastane raw materials, the customary aromatic diisocyanates are optionally used in a mixture with small proportions of aliphatic and / or cycloaliphatic diisocyanates. Particularly useful results are obtained with the diisocyanates mentioned below: 2,4-tolylene diisocyanate and corresponding isomer mixtures, and also 4,4'-diphenylmethane diisocyanate (MDI) or corresponding isomer mixtures. It is of course possible to use mixtures of aromatic diisocyanates.

Another embodiment of the synthesis of elastane raw materials consists in mixing polyester and polyether-polyurethane prepolymers and then converting them into polyurea polyurethanes in a known manner. The mixing ratio of polyester and polyether diols, which is favorable for the respective technical purpose, can easily be determined by preliminary tests.

In the polyurea-polyurethane synthesis, the urea groups are introduced into the macromolecules by a so-called chain extension reaction. The prepolymers ("macrodiisocyanates") containing NCO end groups and synthesized in the prepolymer stage are usually reacted in solution with diamines. Suitable diamines are, for example, ethylenediamine, tetramethylenediamine, 1,3-cyclohexanediamine, isophoronediamine and mixtures of these diamines. By using a small amount of monoamines, for example diethylamine or dibutylamine, during the chain extension, the desired molecular weight of the polyurea polyurethanes can be set. The chain extension itself can be carried out discontinuously or continuously, and optionally using CO ₂ as a retardant.

A mixture of polyester and polyether polyurethane ureas can also be produced after the synthesis of the individual components has been completed.

The reactions are usually carried out in an inert polar solvent such as dimethylformamide or dimethylacetamide.

A number of conventional additives can also be mixed into the polymer solution intended for spinning, e.g. Antioxidants and light stabilizers against polymer degradation or discoloration, further stabilizers against nitrogen oxide yellowing, pigments, e.g. Titanium dioxide or ultramarine blue, dyes, processing aids such as lubricants and non-stick agents based on (earth) alkali stearates, internal release agents based on polydialkylsiloxanes and / or polyether polysiloxanes, as well as additives to prevent chlorine water degradation, e.g. Zinc oxide.

The spinning solutions with a solids content of 20 to 40 wt .-%, preferably 22 to 30 wt .-% based on fiber polymer and a viscosity of 50 to 350 Pa · s at 25 ° C are subjected to a dry spinning process according to the invention, the e.g. can correspond to the embodiment disclosed in the patent specification DE 35 34 311.

DE 35 34 311 C2 describes a spinning head for the production of elastomer threads from spinnerets with one or more bores, feed lines for the liquid material to be spun, a spinning gas flow and distribution, and a method, in particular a dry spinning method, for producing elastomer threads from a spinning solution.

DE 35 34 311 C2 claims a spinning head made of spinnerets with one or more bores, feed lines for the material to be spun, a spinning gas supply and distribution, which is characterized in that the spinning gas supply consists of a central gas tube and the spinning gas distribution consists of a cylindrical one Chamber into which the gas pipe opens, the diameter of which is at least three times as large as the diameter of the central gas pipe, the height of which is a maximum of 25% of the chamber diameter, which has a gas-permeable base with a free area of 2 to 15% and in which below the Central baffle a baffle plate system is attached, which consists of several horizontally and concentrically spaced, overlapping circular rings with a diameter and a circular plate.

Divisible elastane multifilament yarns with two to six individual filaments and a total titer of 15 to 120 dtex are accessible with the method according to the invention. A preferred embodiment of the method according to the invention provides elastane multifilament yarns with a total of 20 to 50 dtex with two individual filaments.

A defined cooling of the threads analogous to JP 03-059 112 is not relevant for the method according to the invention and the purpose pursued thereby. In contrast, however, the described design of the spinneret geometry and the laminarization of the gas flow in the spinning shaft, as z. B. is described in the patent specification DE 3 534 311, crucial. This is the only way to ensure that the extrudate filaments that are still plastic at the beginning of the spinning shaft passage do not come into contact with one another. While JP 03-059 112 describes a type of aftertreatment, the present invention relates to the spinning process (spinneret and shaft). The present method is thus simpler and does not require the additional process step of separate cooling.

The elastane multifilament yarn wound on a spool can be used in processing techniques in which a single elastane filament is used if the multifilament yarn is separated into individual filaments before or during processing. Examples of such processing techniques are e.g. circular knitting or the production of combination yarn with a core made of elastane yarn and a wrapped, blown or wound cover made of non-elastic yarn, e.g. Nylon or cotton. The separation of the elastane multifilament yarns according to the invention into individual filaments takes place between the elastane delivery plant and the spinning, blowing or winding. The division takes place by simply inserting the separate individual filaments into their respective processing organs and starting the processing process. If necessary, the separation process can be further supported by attaching pins or spikes in front of the processing element.

The elastane multifilament yarns according to the invention show high uniformity and excellent processing behavior and do not differ from conventionally produced elastane yarn spun directly to the final titer. The divisibility also allows a spinning station to produce a number of elastane yarns corresponding to the number of single filaments of a particular single filament titer generate, which significantly increases the economy of the manufacturing process, especially the space-time yield. In other words, this manufacturing process results in a multiple of fine titer elastane yarn per unit time than when using a conventional spinning process that leads directly to the final titer.

Examples

The invention is illustrated by the following examples.

In all examples, the elastane fiber polymer is obtained from a polytetramethylene ether-α, ω-diol of number average molecular weight 2000, e.g. Terathane 2000, commercial product from DuPont de Nemours, which is capped with methylene bis (4-phenyl isocyanate) (MDI, commercial product Desmodur 44 from Bayer AG) to form the NCO prepolymer and with a mixture of ethylenediamine (EDA) and diethylamine (DEA ) chain is extended to the polymer. The elastane fiber polymer was made following essentially the same procedure for each of the following examples.

530 parts by weight of polyether diol of molecular weight 2000 are mixed with 359 parts by weight. Dimethylacetamide and 108 parts by weight. MDI mixed at 25 ° C, heated to 50 ° C and kept at this temperature for 95 min. The result is an NCO prepolymer with 2.20% by weight of isocyanate end groups. The prepolymer is then cooled to 20 ° C. and diluted with 598 parts by weight of DMAC.

100 parts by weight of this diluted prepolymer are mixed intensively in a continuous reactor with 31.67 parts by weight of DMAC, 0.58 parts by weight of EDA and 0.66 parts by weight of a 10% solution of DEA in DMAC and converted into a polymer solution which has a solids content of 30% by weight, a viscosity of 124 Pa · s at 50 ° C and an inherent viscosity η _inh of 1.4 dl / g.

This spinning solution are mixed through various stock solutions the following additives (all figures in wt .-% based on fiber solids): 1 wt .-% Cyanox 1790 ^®, 3.75% basic polyurethane from dicyclohexylmethane and (Cytec, USA, stabilizer.) Bis-2-hydroxypropyl-N-methylamine (nitrogen oxide quencher), 0.05% by weight titanium dioxide, 0.2% by weight magnesium stearate (lubricant), 0.3% by weight polyether siloxane Silwet L 7607 (Fa. OSI, antistatic) and optionally 1% by weight of polydimethylsiloxane (internal release agent).

Example 1:

A polyurethane polyurea spinning solution was prepared as described above. It contained 0.35% by weight of magnesium stearate based on the solid and 0.98% by weight of polydimethylsiloxane (Baysilone M 100, commercial product from Bayer AG), 0.35% by weight of siloxane wetting agent (Silwet L 7607, commercial product from OSI Inc.) and 0.05% by weight of titanium dioxide (Rutile RKB 2 from Bayer AG). The solution was dry-spun in a manner according to the invention on a spinning apparatus, in the spinning head of which 8 nozzles with two nozzle holes each 0.3 mm in diameter were arranged such that their distance on the common nozzle plate was 54 mm and the distance from two nozzle holes on adjacent plates was at least 62 mm was. The vertical spinning apparatus had tempered wall surfaces, which were kept at about 220 ° C. Through a fine wire screen in the spinning head, spinning gas was fed in at 55 Nm ³ / h at 290 ° C. in a laminar flow. At the lower end of the spinning apparatus, the individual filaments formed were passed through a first thread guide element with circular ceramic eyelets and then two of these individual filaments were combined in a second thread guide element with a comb-like shape to form a multifilament yarn. The multifilament yarns then passed through an infeed godet, a preparation oil applicator roller and a second godet before they were wound up at 880 m / min into bobbins with 560 g support. The multifilament yarn according to the invention had a titer of 45 dtex.

The yarn mentioned has now been used in a manufacturing process for combination yarn. For this purpose, a wrapping yarn machine, such as e.g. is described by H. Gall and M. Kausch in Chap. 13 polyurethane elastomer fibers in Becker / Braun: Kunststoff-Handbuch vol. 7 Polyurethane, Carl Hanser Verlag, Munich, 1993, p. 689, the elastane multifilament yarn according to the invention put on and processed into a winding yarn with nylon yarns as a sheath, divided into two adjacent hollow spindles . The bobbins ran without a thread break in the dividing zone and in the transport unit and spindle area of the winding machine and gave satisfactory combination yarn.

The separability of these threads according to the invention was also given in an experiment on a blown yarn machine. Here, take-up bobbins were processed to single-filament end bobbins at a take-off speed of over 100 m / min.

Example 2:

The procedure was as in Example 1, but using a spinning solution containing 0.25% by weight of magnesium stearate, 0.7% by weight of polydimethylsiloxane and 0.25% by weight of siloxane wetting agent. Spinnerets with a nozzle hole spacing of 34 mm were used on the nozzle plate. At the end of the spinning apparatus, the 8 multifilament yarns, each consisting of two filaments, were passed through a conventional twist device, in this case an air rotating nozzle, whereby conditions for less false twist were set compared to the normal process. The result was a dtex 45 multifilament yarn with two individual filaments, which could be split up by hand.

A thread break occurred on the winding machine (see Examples 1) during processing under the conditions for producing winding yarn (draw-off by 5 m / min) approximately every 10 minutes. Investigations showed that the individual filaments of the multifilament yarn were fused together at the break points.

From the examples it can be seen that compliance with the dry spinning process according to the invention is necessary to produce the elastane multifilament yarn according to the invention. Without this being provable in every detail, it is assumed that in order to produce the divisible elastane multifilament yarns during their manufacture, such geometric and physical conditions must exist along the thread path through the spinning apparatus that contact, swirling or other intensive contacting is avoided.

Claims (6)

Process for the production of divisible elastane multifilament yarns, characterized in that a dry spinning process is used in which 1) one or more multi-hole spinnerets are used in the spinning head of a dry spinning apparatus known per se, the individual bores of which lie on a plate, the distance x of the bores from one another on a nozzle plate and their distance y from bores on adjacent multi-hole spinneret plates obeys the following relationship: 40 mm <x <y <500 mm 2) prevents turbulence of the individual filaments from a multi-hole nozzle and from adjacent multi-hole nozzles in the dry spinning apparatus by laminarizing the gas flow, 3) the elastane yarns formed after leaving the spinning shaft through a first thread guide with an opening per single filament and then through a second thread guide, in which several individual filaments are combined to form a multifilament, and 4) the multifilament yarn is wound up. A method according to claim 1, characterized in that the gas flow is laminarized by using a spinning head which consists of spinnerets with one or more bores, feed lines for the material to be spun, a spinning gas supply and distribution, and in which the spinning gas supply consists of a central gas tube and the spinning gas distribution from a cylindrical chamber into which the gas pipe opens, the diameter of which is at least three times as large as the diameter of the central gas pipe, the height of which is a maximum of 25% of the chamber diameter, which has a gas-permeable base with a free area of 2 to 15% has and in which a baffle plate system is attached below the central gas pipe, which consists of several horizontally and concentrically spaced from each other overlapping circular rings with a diameter and a circular plate. Method according to Claims 1 to 2, characterized in that an eyelet plate is used as the first thread guide element and a comb thread guide is used as the second thread guide element. Process according to claims 1 to 3, characterized in that the elastane multifilament yarns consist of two to six individual filaments and have a titer of 10 to 120 dtex. Method according to claims 1 to 4, characterized in that the elastane multifilament yarns preferably consist of two individual filaments and have a titer of 30-50 dtex. Elastane multifilament yarns obtainable from a process according to claims 1 to 5.