EP0756026B1 - Process for manufacturing divisible thanelast-yarns - Google Patents

Description

The invention relates to a production method for divisible elastane multifilament yarns, which is carried out so that a coalescence of the yarn forming Single filaments caused by fusing, gluing or mechanical Whirling or twisting is prevented. The available from the process Single filaments can be removed from the multifilament spool divided and processed separately in textile production processes become.

A generic method is for example known from DE-A-3 534 311.

Elastane fibers are fibers made up of at least 85% by weight segmented polyurethanes exist. Reach your typical property profile these fibers through the use of polyurethane polyureas from oligomers Polyester or polyether diols, aromatic diisocyanates and short-chain aliphatic diamines. The thread is usually formed by spinning of solutions of the polyurethanes after the wet spinning or preferably after the dry spinning process, using polar solvents in both cases Solvents such as dimethyl sulfoxide, N-methylpyrrolidone, dimethylformamide or preferably dimethylacetamide are suitable.

Commercial elastane yarns have been known for a long time. They serve because of their elastic properties for the production of functionalized textile products, i.e. Articles with a combination of elasticity and reset or Forming force. To do this, the elastane filament yarn is combined with other inelastic yarns refined to combination yarns, e.g. by winding, spinning or Swirling, or it will go straight through with the inelastic yarn Mesh formation to the flat structure processed, 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 state of the Technology teaches that the spandex yarns are coalesced multifilament yarns be generated. This means that the individual filaments forming the total yarn during their spinning, e.g. in the dry spinning process, with each other are virtually glued. A method of making coalesced Elastane yarn is e.g. in US 3 094 374 and European Patent application 182 615. in the former scripture Advantages of a multifilament with high interfilamentary adhesion in relation to Secure processing is expressly described and methods for setting this Property profile disclosed.

Therefore, it was not expected that elastane multifilament yarns with good processing properties can also be obtained if the process for their Production deliberately keeps the interfilamentary adhesion low or avoids it.

in published patent application JP 03-059 112 are bundled polyurethane multifilaments or monofilaments described in an aligned manner are wound on a spool, the bundled multi or monofilaments have a separation voltage of 15 mg or less when detached from the coil. They are called separate multifilaments or monofilaments at one speed processed of at least 150 m / min. These products are obtained by the filaments coming from the dry spinning apparatus are cooled to below Subject to 60 ° C and adds a metal soap to the product. For the procedure According to JP 03-059 112, it does not matter whether multi or monofilaments are separated become.

The object of the invention is the production of multifilament yarns which Processing from the bobbin into its individual filaments are divisible. These are not allowed twisted together, swirled or glued to one another at certain points or longitudinally his. It is important to find such rare, i.e. at hundreds of intervals To completely prevent the effects that occur.

That will solve this problem Proposed method according to claim 1.

The invention relates to a manufacturing process for the production of so-called divisible splicable elastane multifilament yarns made from known polyurethane polyureas by spinning a spinning solution using the dry spinning method using a Dry spinning apparatus with one or more multi-hole spinnerets, Laminarization of the gas flow in the dry spinning apparatus to prevent the Swirling the individual filaments from the multi-hole nozzle and from neighboring ones Multi-hole nozzles, guide the elastane yarns formed after leaving the Spinning shaft through thread guide elements and winding of the multifilament, thereby characterized in that one or more multi-hole spinnerets are used, the Single holes are on a plate, the distance x of the holes from each other on a nozzle plate and their distance y to holes neighboring multi-hole spinneret plates of the relationship: 40 mm <x <y <500 mm obeyed, and that the elastane yarns formed after leaving the spinning shaft through a first thread guide element with an opening per single filament and then through a second thread guide can be performed, in which several individual filaments to one Multifilament can be summarized.

The polyurea polyurethanes are produced by methods known per se. The synthetic structure of the fiber raw materials after the Prepolymer process, wherein in a first step a long-chain diol in Solvent or in the melt with a diisocyanate to form a prepolymer implemented that the reaction product isocyanate end groups (NCO groups) contains.

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. Have this generally a number average molecular weight of 1000-6000.

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

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

Polyester and / or polyether diols can also be used in combination with diols contain tertiary amino groups, are used. For example, N-alkyl-N, N-bishydroxyalkylamine. For example, here are connections called:

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.

The usual aromatic diisocyanates are used in the synthesis of elastane raw materials optionally in a mixture with small amounts of aliphatic and / or cycloaliphatic diisocyanates used. Particularly useful Results are obtained with the diisocyanates mentioned below: 2,4-tolylene diisocyanate and corresponding mixtures of isomers, and also 4,4'-diphenylmethane diisocyanate (MDI) or corresponding isomer mixtures. Of course it is possible to mix aromatic diisocyanates use.

Another embodiment of the synthesis of elastane raw materials is Mix polyester and polyether polyurethane prepolymer and then in implement known manner to polyurea polyurethanes. That for the respective technical purpose favorable mixture ratio of polyester and Polyether diols can be easily 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 synthesized in the prepolymer stage are usually reacted in solution with diamines. Suitable diamines are, for example, ethylenediamine, tetramethylene diamine, 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 generated after completion of the synthesis of the individual components.

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

The polymer solution intended for spinning can be a number of more common Additives are mixed in, 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 polyetherpolysiloxanes, as well as additives against chlorine water degradation, e.g. Zinc oxide.

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

DE 35 34 311 C2 describes a spinning head for the production of elastomer threads from spinnerets with one or more holes, supply lines for the spinning liquid material, a lead gas distribution and distribution and a process in particular a dry spinning process for the production of elastomer threads from a spinning solution.

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

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

For the method according to the invention and the purpose pursued by it is a defined cooling of the threads analogous to JP 03-059 112 not relevant. Against it but the described design of the spinneret geometry and the laminarization the gas flow in the spinning shaft, as z. B. in the patent DE 3 534 311 is crucial. This is the only way to ensure that the No plastic extrudate filaments at the beginning of the spinning shaft passage come into contact with each other. While JP 03-059 112 a kind Aftertreatment describes, the present invention is in the field of Spinning process (spinneret and shaft). This is the present procedure simpler, it comes without the additional process step of separate cooling out.

The elastane multifilament yarn wound on a spool can be found in such Use processing techniques in which a single elastane filament is applied if you put the multifilament yarn in before or during processing Separates individual filaments. Examples of such processing techniques are e.g. circular knitting or the production of combination yarn with one soul Elastane yarn and a wrapped, wrapped or wrapped cover non-elastic yarn, e.g. Nylon or cotton. The separation of the invention Elastane multifilament yarns in single filaments are made between the elastane supply plant and the wrapping, blowing or winding. The Division takes place by simply inserting the separate individual filaments into it respective processing organ and start of the processing process. One can if necessary by attaching pins or thorns before the Processing organ further support the separation process.

The elastane multifilament yarns according to the invention show high uniformity and excellent processing behavior and are no different from conventionally produced elastane yarn spun directly to the final titer. The Divisibility also allows a single filament number from a spinning station corresponding multiple of elastane yarn of a certain single filament titer generate, thereby increasing the economics of the manufacturing process, in particular the space-time yield is significantly increased. In other words, means this is that with this manufacturing process in the unit of time a multiple Fine titer elastane yarn is obtained than when using a conventional, directly to the final titer of the spinning process.

Examples

The invention is illustrated by the following examples.

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

530 parts by weight of polyether diol of molecular weight 2000 are 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 a NCO prepolymer with 2.20% by weight isocyanate end groups. Then that will Cooled prepolymer 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.

The following additives are added to this spinning solution via various master batches added (all data in% by weight based on the fiber solids): 1% by weight Cyanox 1790® (Cytec, USA, stabilizer), 3.75% basic polyurethane. out Dicyclohexylmethane diisocyanate and bis-2-hydroxypropyl-N-methylamine (nitrogen oxide quencher), 0.05% by weight of titanium dioxide, 0.2% by weight of magnesium stearate (Lubricant), 0.3 wt.% Polyether siloxane Silwet L 7607 (from 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) the OSI Inc.) and 0.05% by weight 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 that were kept at about 220 ° C. Through a fine wire screen in the spinning head, spinning gas at 55 Nm ³ / h at 290 ° C was fed 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 was now in a manufacturing process for combination yarn used. For this purpose, a wrapping yarn machine, such as e.g. described is by H. Gall and M. Kausch in Chap. 13 polyurethane elastomer fibers in Becker / Braun: Plastic Handbook Vol. 7 Polyurethane, Carl Hanser Verlag, Munich, 1993, p. 689, put on the elastane multifilament yarn according to the invention and divided into two adjacent hollow spindles to form a winding yarn processed with nylon yarns as a cover. The bobbins ran in without thread break the dividing zone and in the conveyor and spindle area of the winding machine and gave satisfactory combination yarn.

The separability of these threads according to the invention was also in an experiment given on a blow yarn machine. Here was with a withdrawal speeds from over 100 m / min feed bobbins processed to single-filament end bobbins.

Example 2:

The procedure was as in Example 1, but using a spinning solution 0.25% by weight of magnesium stearate, 0.7% by weight of polydimethylsiloxane and 0.25 wt .-% siloxane wetting agent used. There were spinnerets with one Nozzle hole spacing of 34 mm is used on the nozzle plate. At the end of The 8 multifilament yarns consisting of two filaments each became spinning equipment passed through a conventional swirl device, in this case an air rotating nozzle, compared to the normal process, conditions for less false twist have been set. The result was a dtex 45 multifilament yarn with two Individual filaments, which could be split up in a manual test.

On the wrapping machine (see examples 1) occurred under the Conditions for the production of wrapping yarn (withdrawal by 5 m / min), for example a thread break every 10 minutes. Investigations showed that at the break points the individual filaments of the multifilament yarn melted together were.

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

Claims (5)

1. A process for manufacturing divisible elastane multifilament yarns by spinning a spinning solution by the dry spinning process by means of a dry spinning apparatus having one or more multi-hole spinnerets, laminarisation of the gas flow in the dry spinning apparatus to suppress entanglement of the individual filaments from the multi-hole spinneret and from adjacent multi-hole spinnerets, guidance through thread guide members of the elastane yarns formed after they leave the spinning cabinet and windup of the multifilament,
   characterised in that
   one or more multi-hole spinnerets are used, whose individual bores are located on a plate, wherein the distance x between the bores on a spinneret plate and their distance y from bores on adjacent multi-hole spinneret plates fulfil the relationship: 40 mm < x < y < 500 mm, and in that the elastane yarns formed are guided, after leaving the spinning cabinet, through a first thread guide member with one opening per individual filament and then through a second thread guide member, in which a plurality of individual filaments are combined into one multifilament.
2. A process according to claim 1, characterised in that the gas flow is laminarised by using a spinning head, which consists of spinnerets with one or more bores, supply lines for the material to be spun and a spinning gas feed and distributor and in which the spinning gas feed consists of a central gas pipe and the spinning gas distributor consists of a cylindrical chamber, into which the gas pipe opens, whose diameter is at least three times as large as the diameter of the central gas pipe, whose height amounts to at most 25 % of the chamber diameter, which comprises a gas-permeable bottom with an open surface area of 2 to 15 %, and in which there is accommodated, beneath the central gas pipe, a baffle plate system which consists of a plurality of spaced, horizontally and concentrically attached, overlapping circular rings of graduated diameters and a circular plate.
3. A process according to claim 1 to 2, characterised in that an eyeletted plate is used as the first thread guide member and a comb thread guide is used as the second thread guide member.
4. A process according to one of claims 1 to 3, characterised in that the elastane multifilament yarns consist of two to six individual filaments and exhibit deniers of from 10 to 120 dtex.
5. A process according to one of claims 1 to 4, characterised in that the elastane multifilament yarns preferably consist of two individual filaments and exhibit deniers of 30 - 50 dtex.