EP0579979B1 - Process for the production of spandex polymer spinning solutions, with stabilized viscosity and low gel content - Google Patents

Description

The invention relates to a method for producing of surprisingly stable in their solution viscosity Spinning solutions of segmented polyurethane urea elastomers in highly polar solvents such as dimethylformamide (DMF) or dimethylacetamide (DMAC) without or with reduced tendency to paste and without or with a very low gel content, characterized by the Use of a multi-stage nozzle reactor device to carry out the procedure.

The subject of the invention is also a multi-stage nozzle reactor without mechanically moving parts as a device, which by very fast and intense Mixing of the reaction components allowed, e.g. segmented polyurethane urea elastomers as homogeneous solutions in highly polar solvents continuously to manufacture.

Another subject of the invention are those according to the method and obtainable by means of this device Elastane spinning solutions or elastane fibers obtainable therefrom.

Elastane fibers are understood to mean threads that are too at least 85% by weight of segmented polyurethane (urea) consist. Such elastane fibers are commonly used made by first making a long chain Diol (macrodiol) terminated with an aromatic diisocyanate is capped so that you get a macro diisocyanate (NCO prepolymer). The NCO prepolymer is then in a second step with a chain extender, which usually consists of a (cyclo) aliphatic Diamine is made up in solution to a high molecular weight Implemented polyurethane urea. These polyurethane ureas are constructed so that the macromolecule Has segment structure, i.e. from high-melting crystalline and low-melting amorphous segments (Hard or soft segments). The hard segments then act in the solid due to their crystallinity as fixed points of the network and are therefore decisive for the firmness and the softening range of the the molded article produced by the polymer. The soft segments however, whose glass transition temperature is below the temperature of use should be for the elasticity of the elastomers (B. v. Falkai, synthetic fibers, Verlag Chemie, 1981, pp. 179 to 187).

The chain extension is usually carried out batchwise in such a way that the chain extender (an aliphatic diamine, preferably ethylene diamine) and possibly a chain terminator, a secondary monoamine, such as diethylamine in a polar solvent (DMF or DMAC) are placed in a stirred kettle ( and preferably mixed with carbon dioxide). The NCO prepolymer is then added to this suspension of the diamine carbamate, which is now preferably obtained by adding CO ₂ and has a reduced reactivity, and an elastomer solution with a defined elastomer solids content is formed with stirring. A disadvantage of this type of production is that the desired viscosity of the elastane solutions is often not in the intended range, which is necessary for further processing and then has to be adjusted to the desired viscosity by subsequent dosing, for example of aliphatic diisocyanates. Another disadvantage is the pasting of parts of the solution and / or the presence of gel particles if not mixed sufficiently. Such elastane solutions cannot then be practically processed further. In addition, discontinuously produced solutions obviously contain more branched polyurethane ureas because of a lack of mixing intensity, which, at a given concentration, have higher viscosities than more linear polyurethane ureas.

To improve economy (fast spinning) and also from an ecological point of view (lowering the proportion of solvents in the elastane spinning solution) should be as possible Elastane spinning solutions with high solids concentrations ≥ 30% spun. At these high solids concentrations however, there are special problems regarding a limited solubility of the polymers, especially with long storage times of the spinning solutions, resulting in a paste or viscosity increase expresses. The increasing insolubility often leads to the fact that the elastane solution is no longer processed or can be spun. The cause of this Phenomena can be of different types.

1. Je niedriger der Lösungsmittelanteil wird, umso schneller tritt die Desolvatation der Weichsegmente, bestehend aus hochmolekularen Polyester-oder Polyetherdiolen (Makrodiolen), bevorzugtes Molekulargewicht von 2.000, ein. Dieser Prozeß wird noch verstärkt, je höher das Molekulargewicht, z.B. 3.000 bis 8.000, des Makrodiols ist. Zudem sind Polyetherdiole in den üblichen Lösungsmitteln schwerer löslich als Polyesterdiole. Verstarkt wird die Desolvatation insbesondere bei Verwendung von Polyether-Polyesterdiol-Mischungen, da diese aufgrund der unterschiedlichen Löslichkeit von vornherein eine Entmischungstendenz durch Mikrophasentrennung aufweisen.

2. Für besondere Anwendungszwecke, bei denen besonders hohe Festigkeiten und Thermostabilitäten erwünscht sind, wird ein höherer Diisocyanatanteil als üblich (NCO-Gehalt bezogen auf Feststoff ≥ 2,5 Gew.-%) eingesetzt. Der dadurch im Elastan bedingte hohe Anteil an Polyharnstoffsegmenten führt zu einer verminderten Löslichkeit und gesteigerter Verpastungstendenz der Elastanlösung.

3. Da bekanntermaßen eine Temperaturerhöhung zu einer Senkung der Lösungsviskosität führt, werden häufig hochkonzentrierte Elastanlösungen bei erhöhter Temperatur, beispielsweise 50°C, gelagert. Dies hat jedoch in vielen Fällen bereits nach 1 bis 2 Tagen eine drastische Viskositätsänderung der Elastanlosung zur Folge, die häufig auf einem Molekulargewichtsaufbau beruht. Es wird vermutet, daß es sich hier im wesentlichen um eine Endgruppenaminolyse handelt, bei der die sekundären Monoamine oder ihre Umsetzungsprodukte (zum Kettenabbruch) durch die primären Aminoendgruppen (aus überschüssigen Diamin-Kettenverlängerungsmitteln wie Ethylendiamin) aus den Harnstoffbindungen verdrängt werden und insbesondere bei etwa äquivalenten Mengen an sekundären und primären Amingruppen zu besonders hohem Viskositätsaufbau führen.

4. Längeres Erhitzen von Elastanlösungen oder -pasten - z.B. 2 bis 5 Stunden auf 80 bis 120°C führt dagegen zumeist zu einem Molekülabbau - erkennbar am Rückgang des η_rel-Wertes der Polymersubstanz mit steigender Einwirkungsintensität-, -, der jedoch schlecht kontrollierbar verläuft, einen hohen Energieaufwand erfordert und häufig zu Elastanlösungen, welche sich nicht oder nur mit vielen Spinnfehlern verspinnen lassen, führt!

The following causes can, for example, lead to a deterioration in solubility in highly concentrated elastane solutions:

1. The lower the proportion of solvent, the faster the desolvation of the soft segments, consisting of high molecular weight polyester or polyether diols (macrodiols), preferred molecular weight of 2,000, occurs. This process is intensified the higher the molecular weight, for example 3,000 to 8,000, of the macrodiol. In addition, polyether diols are less soluble in common solvents than polyester diols. Desolvation is intensified particularly when using polyether-polyester diol mixtures, since these have a tendency to segregate due to the different solubility due to micro-phase separation.

2. For special applications in which particularly high strengths and thermal stabilities are desired, a higher proportion of diisocyanate than usual (NCO content based on solids ≥ 2.5% by weight) is used. The resulting high proportion of polyurea segments in the elastane leads to a reduced solubility and an increased tendency to paste the elastane solution.

3. Since it is known that an increase in temperature leads to a reduction in the solution viscosity, highly concentrated elastane solutions are often stored at elevated temperature, for example 50 ° C. In many cases, however, this results in a drastic change in the viscosity of the elastane solution after only 1 to 2 days, which is often based on a molecular weight build-up. It is believed that this is essentially an end-group aminolysis in which the secondary monoamines or their reaction products (for chain termination) are displaced from the urea bonds by the primary amino end groups (from excess diamine chain extenders such as ethylenediamine) and in particular in the case of approximately equivalent ones Amounts of secondary and primary amine groups lead to a particularly high increase in viscosity.

4.Longer heating of elastane solutions or pastes - e.g. 2 to 5 hours at 80 to 120 ° C usually leads to a degradation of the molecule - recognizable by the decrease in the η _rel -value of the polymer substance with increasing exposure intensity-, - which, however, is difficult to control , requires a lot of energy and often leads to elastane solutions that cannot be spun or can only be spun with many spinning defects!

If the polyaddition (chain extension) in the usual polar organic solvents used for this, in particular with ethylenediamine the solubility decreases with increasing molecular weight, so that pasting must be expected. Therefore one often leaves the polyaddition at discontinuous Work up to a specified viscosity and / or uses a monofunctional chain terminator, such as dibutylamine, octylamine, butanone oxime (Houben Weyl Volume E 20 / Part 2, p. 1642), but preferably diethylamine (Ullmann's Encyclopedia of Industrial Chemistry, Vol. A 10, p. 612). So you get at the same time a narrower molecular weight distribution.

In order to achieve sufficient mixing of the aliphatic (di) amine mixture with the NCO prepolymer solution before the very fast aliphatic amine / NCO reaction, carbon dioxide is added to the (di) amine mixture in the batchwise reaction procedure. The resulting carbamate suspension then reacts very slowly with the NCO prepolymer, releasing CO ₂ (see DE-A-1 223 154 or DE-A-1 222 253). In contrast, in a method without carbon dioxide, very rapid mixing must be achieved with one device.

The quick mixing of two or more reactive Liquids are inherent in polyurethane chemistry Common technique for performing polyaddition reactions of NCO precursors with water, aliphatic Diols or aromatic diamines. Everyone has to Process operations such as dosing, mixing and Filling moldings before the start of chemical Most of the reaction (pot life) has been completed.

The central operation is the mixing of specified amounts of liquid. This includes mixing in batch with mechanical Stirrers or as they pass through rotor / stator dispersing machines and prick mixers (see plastic manual, Volume 7, Carl Hauser Verlag 1977). Furthermore is mixing with high pressure mixers in PU technology usual (see H. Proksa, plastic consultant 3/1988; High pressure mixing, pioneer of modern PU technology), being two reaction components under high pressure over Nozzles jetted together in a small mixing chamber and are mixed by the intense turbulence (see DE-A-2 344 135 and DE-A-1 157 386). The response times such polyurethane reactions are at least in the second range.

However, since the polyaddition reactions of NCO precursors with the aliphatic diamines during elastane production take place considerably faster than with diols, water or aromatic diamines and highly viscous reaction products are formed in the millisecond range, these devices are little for the continuous chain extension of NCO prepolymers with diamines Suitable: The reaction proceeds faster than the mixing of the reaction components can take place. Unless the available mixing time can be extended considerably by adding reaction-inhibiting additives, such as adding dry ice (CO ₂ ) to the diamine, so that the reaction proceeds via the much slower-reacting carbamate stage and / or additionally through the lower temperature is braked.

EP-A-399 266 describes a process for the production from highly concentrated, finely divided dispersions the melt of high-melting organic compounds, however no reaction mixtures, described, by using a melt to form a pre-suspension into a colder liquid phase at a temperature below metered the crystallization temperature and this pre-emulsion in a downstream homogenizing nozzle finely dispersed. As a disperser i.a. an emulsifying device with a mixing nozzle and specified a downstream homogenizing nozzle.

The same applies to simple mixing nozzles in one DC reactor, which e.g. according to EP-A-0 303 907 for the production of aqueous polyurethane dispersions used by using an NCO prepolymer with water mixed.

Such dispersing devices are in their mixing times still too slow, and are only suitable if the response time is more than 0.1 seconds.

Without deactivation e.g. with carbon dioxide Polyadditions with aliphatic or cycloaliphatic Diamines or with by catalyst or raising the Reactivity accelerated mixing temperature Diols, do not perform. Such manufactured Reaction solutions then contain specks and gel bodies and are therefore suitable for further processing (in particular interference-free spinning) not suitable.

The object of the invention was therefore to implement a cost-reducing and also environmentally friendly manufacturing process (Use less solvent and Improvement of economy through fast spinning) for highly concentrated elastane spinning solutions with improved flow properties (Improved spinnability through a lower Solution viscosity while maintaining the necessary molecular weights) and an improved viscosity constancy long storage times of spinning solutions without loss in thermal and elastic behavior of the resulting End products as well as a gel-free form of spinning solutions with increased linearity of the polymer.

These advantages as they appear from the description and the Examples could emerge from the Use of the mixing and homogenizing device according to the invention (in the form of a multi-stage nozzle reactor) can be achieved in the polyaddition. Here were simple but highly effective mixing devices largely used without mechanically moving mixing units, however, these need to be used in a certain way fastest reaction processes are constructed and preferably contain several levels.

The invention relates to a continuously operated Process for the production of highly concentrated Elastane spinning solutions with improved flow properties and high viscosity constancy with a long service life Maintaining the usual level of thermal and elastic properties the one available from these solutions Elastane fibers preferably available from accordingly produced segmented polyurethane ureas with certain monoamines and / or monoisocyanates as chain terminators.

According to the method of the invention can easily highly concentrated elastane spinning solutions based on Polyurethane ureas with a solids content of up to 40 wt .-% are produced, which is excellent Solubility and constant viscosity, even when adjusted a higher proportion of hard segments e.g. by a higher proportion of diisocyanate, and surprisingly also a reduction in the viscosity of the elastane spinning solution have at the same concentration of the polymer.

It has now surprisingly been found that homogeneous, highly concentrated, excellent viscosity stability Spinning solutions preferably both made of polyester or Polyether diols as well as in particular from mixtures of Polyester and polyether diols, with excellent Flow properties and therefore better spinnability according to the procedure, if you are in the Chain extension stage (polyaddition) the mixing and Homogenizing device (multi-stage nozzle reactor) working continuously starts. Due to the very quick mixing during the The reaction process can then be used e.g. of carbon dioxide as Reaction inhibitors can be dispensed with.

The invention relates to a continuous process for the production of highly concentrated elastane spinning solutions with improved flow properties and high viscosity constancy from fast reacting polyaddition components, characterized in that the reaction components from the Batch containers in a multi-stage nozzle reactor consisting of a Mixing chamber with a fabric nozzle, a mixing nozzle and a homogenizing nozzle, which are connected in direct succession, are continuously metered in the first stage of the multi-stage nozzle reactor, the reaction components in the mixing nozzle of the reactor can be mixed with each other in up to 10 ms reacting mixture in a second stage, in a homogenizing nozzle is homogenized and then in a downstream reactor is reacted.

The invention is explained in more detail below with the aid of figures:

Fig. 1a shows a section through a nozzle reactor with short residence times of the reaction mixture in the area of the mixing chamber (not according to the invention).

1b shows a section through a known nozzle reactor with a long one Residence time of the reaction mixture (>> 100 ms) in the area of the mixing chamber.

Fig. 2 shows schematically a section through an inventive Multi-stage nozzle reactor.

3 shows a diagram of the overall method according to the invention for Production of spinning solutions.

The multi-stage nozzle reactor device according to the invention makes it possible to mix reactive components faster than the reaction expires (e.g. ≤ 10 ms) (Fig. 2). The well-known arrangement (see Fig. 1b) is unsuitable because of the mixing the components run too slowly. (The dwell time the reaction mixture here is > 100 ms). As can be seen from the drawing (Fig. La), the fabric nozzle (21) and the mixing nozzle (22) must be very be closely linked to one another for fast, optimal Mixing and reducing backmixing to guarantee.

3 shows the flow diagram of the method according to the invention essentially for continuous polyurethane urea chain extension from NCO prepolymer solution and (cyclo) aliphatic diamines. In the invention Short-term mixing and homogenizing device after Fig. 2 (called nozzle reactor), the two material flows e.g. NCO prepolymer solution (B) and aliphatic Diamine solution (A) using metering pumps 5 and 6 from the Batch containers 3 and 4 metered in continuously. The Mixture preparation of the amine solution (chain extender, chain terminator and solvent) and the NCO prepolymer solution (NCO prepolymer and solvent) can weighed into the templates or using dosing pumps be produced continuously.

The multi-stage nozzle reactor (see e.g. Fig. 2) exists from a series connection of different nozzles namely the fabric nozzle 1, the mixing nozzle 2 and the homogenizing nozzle 7 with the holes 8 and in a preferred Execution of the displacer 9. Fabric nozzle and Mixing nozzle are connected in direct succession, so that the residence time until complete mixing the amine stream (A) with the prepolymer stream (B) in a time of ≤ 10 ms, preferably 0.1 to 5 ms is. Both nozzles 1 and 2 are designed that there is an injector effect and backmixing avoided in the area 10 between the two nozzles becomes.

The homogenizing nozzle is connected to the injector part 7 with the holes 8, which is already reacting Reaction mixture homogenized again intensively. In order to the mixing with the lowest possible viscosity is the volume between the mixing and homogenizing nozzle minimized by a displacer 9.

One of the possible constructive embodiments shows 2.

The preferred overall method is shown in FIG. 3 further explained:

Immediately behind the actual multi-stage nozzle reactor the reaction solution gets into the buffer tank 11, (Fig. 3), which has the task of the nozzle reactor with its upstream dosing pumps, hydraulic from the downstream piping system with to decouple the discharge pumps 12 and 13. Hereby back impulses to the metering pumps 5 and 6, the Can cause fluctuations in the microdosing range, prevented. Direct introduction to would also be possible a spinning kettle.

The course of the reaction can be measured by direct pressure measurement in the nozzle reactor e.g. between mixing nozzle 2 and homogenizing nozzle 8 are tracked.

The degree of polymerization of the polymer solutions can be about the viscosity measuring devices 14 and 15 are tracked. There the reaction in the buffer tank 11 under certain circumstances has not yet been fully completed and thus the use of viscosity as a control variable for Control of the recipe is difficult, the buffer boiler 11 preferably with a pumping circuit and this particularly preferably provided with a heat exchanger 16. So-called heat exchangers 16 come in particular KSM heat exchanger (the heating or cooling coil is in a tube shaped like a static mixer). By heating to about 50 to 60 ° C in this Area achieved a complete implementation, so that with the viscosity measured value 14 through the viscosity constancy Regulation of the metering pumps 5 and 6 can be achieved. Other possible intervention parameters for controlling the Viscosity are continuous or gravimetric Weighing of the amine boiler via the ratio of chain extender to chain terminators or by the amount of selected amine excess over the NCO end group content. The pressure can be at various points on the device be tracked via pressure gauges 17.

The advantages of the method lie in the achievement high throughputs in the nozzle reactor with uniform Product quality (e.g. regarding molecular weight distribution) and product concentration since each volume of reaction solution with exactly the same shear and concentration conditions mixed and thus for reaction was brought and practically no way to Side reactions (e.g. cross-linking reactions) exist.

The segmented polyurethane urea elastomers constructed according to the invention deliver clear, gel-free stable Spinning solutions that according to usual wet and special after the dry spinning process even with high solids concentration (e.g. 30 to 40% by weight) very well processed can be. The inventive preferably have highly concentrated spinning solutions excellent viscosity stability both at 25 ° C as well as at 50 ° C with storage times (e.g. also at high Concentrations) up to at least 5 days and longer.

Surprisingly, those produced according to the invention Spinning solutions have a lower viscosity given solid concentration as such elastomer solutions, those after discontinuous polyaddition processes getting produced. It is believed that a linear polymer structure is achieved, which is not only on productivity, but also on a better one Spinning behavior of the elastane solutions.

By using the multi-stage according to the invention Nozzle reactor as a mixing and homogenizing device, preferably with a downstream buffer tank, Pump circulation and heat exchanger, enables the invention Manufacturing process accordingly using advantages such as improved solubility, reduced viscosity, Viscosity constancy also with longer storage time and elevated temperature as well as improved Quality constancy, the production of Elastomer threads without sacrificing thermal and mechanical property profile of the elastane threads.

The invention also relates to threads or fibers, prepared from the spinning solutions according to the invention.

The elastane solutions according to the invention can also be used for Manufacture of films, foils, tubes or coatings be used.

The production of the polyurethane urea elastomers according to the invention can according to known process steps respectively. The synthesis has proven particularly successful according to the NCO prepolymer process, the first Process step a higher molecular weight diol a) in the solvent or in the melt with diisocyanate c), if appropriate in the presence of low molecular weight diols b) an NCO prepolymer is reacted so that the NCO prepolymer Contains NCO end groups in a certain amount.

As long-chain, high-molecular dihydroxy compounds a) (also called macrodiols) are especially polyester diols and polyether diols. These diols generally have molecular weights from 1,000 to 8,000, preferably 1,500 to 4,000.

As polyester diols e.g. Aliphatic dicarboxylic acid polyester Suitable dicarboxylic acids, both several Diols as well as several dicarboxylic acids or hydroxycarboxylic acids can contain. Mixed adipic acid esters are particularly suitable from adipic acid, 1,6-hexanediol and neopentyl glycol, Adipic acid, 1,4-butanediol and neopentyl glycol or adipic acid, 1,4-butanediol, neopentyl glycol and 1,6-hexanediol.

Particularly suitable as long-chain polyether diols Polytetramethylene oxide diols or their copolyethers with others ether-forming compounds such as ethylene oxide or Propylene oxide. Mixtures of the above can also be used Connections are used.

Other high molecular weight diol compounds, (macrodiols) e.g. Dihydroxylactone esters or dihydroxypolycarbonates as known from the prior art can also are used, as well as others, in the state of the Technology known high molecular weight diols. These include also diols linked to diisocyanates (e.g. in molar ratio OH / NCO = 2: 1 to 5: 4).

Low molecular weight diols b) are e.g. Ethylene glycol, 1,2-butanediol, 1,4-butanediol, 1,4-and / or 1,3-cyclohexanedimethanol, N, N-bis (β-hydroxypropyl) methylamine, N, N'-bis (β-hydroxyethyl) piperazine, N, N-dimethyl-N, N'-hydroxyethyl hydrazine and other connections of this Substance classes.

The usual aromatic diisocyanates c) Diisocyanates are used. You will if necessary in combination (with smaller proportions) of (Cyclo) aliphatic diisocyanates, but optionally the (cyclo) aliphatic diisocyanates are used alone. You get particularly useful results with 4,4'-diphenylmethane diisocyanate or corresponding isomer mixtures with minor amounts of 2,4'- and / or 2,2'-isomers, and with toluene diisocyanate (TDI). Of course it is possible to use mixtures of aromatic To use diisocyanates. As mixture components or individual components are still, for example the following (cyclo) aliphatic diisocyanates are suitable, in particular 1,6-hexamethylene diisocyanate, 1,8-octamethylene diisocyanate, 2/3-methylhexamethylene diisocyanate-1,6 or 2,4-diisocyanato-1-methyl-cyclohexane as well as the 4,4'-dicyclohexylmethane, 4,4'-dicyclohexylalkylidene, 4,4-dicyclohexyl ether diisocyanate or isophorone diisocyanate in their various stereoisomers or stereoisomer mixtures.

In the synthesis of the segmented elastomers after the The macrodiols in the NCO prepolymer process Melt or in a solvent with excess molar amounts of diisocyanates c) via the diols (a + b) implemented so that the reaction product isocyanate end groups contains. The OH / NCO ratios are between 1: 1.4 to 1: 4.0, preferably 1: 1.6 to 1: 3.8, selected, so that NCO prepolymers with an NCO content of 1.4 to about 4.5% by weight, preferably 1.8 to 4.0% by weight, of NCO, arise. The OH / NCO ratio must be dependent of the molecular weight of the macrodiol within the ratio specified here are chosen so that the NCO content of the NCO prepolymer in the here measured Area falls.

As catalysts are for the NCO prepolymer production suitable: Lewis acid catalysts such as tin salts or e.g. Organotin compounds such as organotin carboxylates or halides, dibutyltin dilaurate, inorganic Organic acid salts, e.g. Tin octoate, tin stearate, Tin acetate, lead octoate, plug-in catalysts such as organotin alcoholates, β-dicarbonyl compounds, oxides, mercaptides, sulfides, organoamine tin compounds, phosphine tin compounds: furthermore are Lewis base catalysts such as tertiary amines, phosphines, pyridines as catalysts suitable, as in the prior art of Polyurethane production are known in principle. Preferably dibutyltin dilaurate (Desmorapid® Z / Bayer AG) or diazobicyclooctane (DABCO®). Mostly the use of catalysts is often omitted however, small amounts of deactivators used against alkali acids.

Become solvents in the prepolymerization reaction chlorobenzene are particularly suitable for this, N-methylpyrrolidone, dimethyl sulfoxide and especially most of them also used as spinning solvents Amide solvent dimethylformamide and dimethylacetamide.

For the synthesis of segmented polyurethane ureas the desired urea groups through a chain extension reaction of NCO prepolymers with diamines introduced into the macromolecules. The one in the NCO prepolymer stage synthesized NCO prepolymers (also Macro diisocyanates are called) in highly polar solvents with chain extenders f), preferably aliphatic diamines and chain terminators / Blocking agents (secondary monoamines) g) accordingly the inventive method using the multi-stage Mixing and homogenizing device according to the invention implemented.

Straight-chain or branched are preferred as diamines f) Diamines used, e.g. 1,2-propylenediamine, 1,4-diaminobutane, 1,6-diaminohexane, 1,3-diamino-cyclohexane or also 1,3-diamino-2,2-dimethylpropane; prefers however, ethylenediamine is the sole or predominant Chain extender used.

Cycloaliphatic diamines can also be used in proportions <50 mol-X are used as co-chain extenders, e.g. 1,3-diamino-cyclohexane.

Secondary amines such as piperazine, N-methylethylenediamine can also be used or N, N'-dimethylethylenediamine as codiamines be used, but this is less preferred.

The chain extension reaction is preferably carried out in solution using highly polar solvents such as dimethyl sulfoxide, N-methylpyrrolidone, but preferably Dimethylformamide or especially dimethylacetamide.

The viscosity of the elastomer solution required for the preferred dry spinning process is generally in the range from 10 to 350 Pa.s at 50 ° C. and a shear rate of 23 s ^-1 , the concentration of the spinning solution being between 18 and 34% by weight. The elastomer solutions produced by the process according to the invention can have solids concentrations of up to 40% and more, the viscosity of the elastomer solution being in the range from 100 to 250 Pa.s at 50 ° C. (shear rate 23 s ^-1 ).

In the dry spinning process, the - if necessary up to heated to approx. 120 ° C - spinning solutions with viscosities of at least 30 Pa.s at 50 ° C through nozzles in one to about 150 to 250 ° C heated, about 4 to 8 m long spinning shaft, in the air heated to about 150 to 350 ° C or blowing in inert gases such as nitrogen or steam will be spun.

The solutions prepared according to the invention have one Viscosity stability of at least ± 20% over at least 5 days, preferably at least 7 days compared to the discontinuous process cheaper.

By using a small amount of a monofunctional Chain terminator during the chain extension reaction, can be the desired molecular weight adjust easily.

Completely surprisingly, according to the invention Process spinning solutions of reduced viscosity with an otherwise identical composition. Hereby becomes a spinning from more concentrated solutions possible.

The elastomer solutions produced according to the invention can also the usual ones for various purposes Additives i) are added in effective amounts. For example, Antioxidants, light stabilizers, UV absorbers, fining dyes, pigments, coloring additives (e.g. oligomers or polymers containing tertiary amine), Antistatic, DMF-soluble silicone oils, adhesive effective additives such as magnesium, calcium, lithium, Zinc and aluminum salts of long chain carboxylic acids such as stearates, palmitates or dimer fatty acids or any Mixtures of these salts or additions of fine particles Zinc oxides, which up to 15% by weight others Oxides, e.g. Magnesium oxide or calcium oxide or carbonates, e.g. Ca or magnesium carbonates can contain. Such zinc oxides with alkaline earth oxides or Carbonates as additives can have excellent chlorine resistance of ether as well as polyester elastomer threads against chlorine water (detergents / swimming pools / bleach) can be achieved without a high Purity requirement, e.g. in zinc oxide or trace sulfur content, should adhere to.

The elastomer solutions obtained by the process according to the invention can according to the specified procedures Spun elastomer threads, but also for film coatings or similar fabrics will. This can be done by drying or by coagulation happen.

The elastomer solutions according to the invention show an unusual one Combination of excellent solubility and constant viscosity, even at high temperature and long storage times.

Measurement methods:

t₁ : Durchlaufzeit (s) der Polymerlösung

t_o : Durchlaufzeit (s) des reinen Lösungsmittels

ηi = ln ηr c umgerechnet. The measurement variables mentioned in the examples were determined as follows: The inherent viscosity (ηi) of the elastomers was determined in dilute solution of 0.5 g / 100 ml of dimethylacetamide at 30 ° C. by determining the relative viscosity η _r compared to the pure solvent and after of the formula η R = t1 t0

t ₁ : throughput time (s) of the polymer solution

t _o : cycle time (s) of the pure solvent

η i = ln η r c converted.

The tenacity was determined based on DIN 53 815 (cN / dtex). The maximum tensile force elongation (in%) was also carried out in accordance with DIN 53 815. The module at 100% or 300% initial elongation was determined in cN / dtex at an elongation rate of 4 x 10 ^-3 meters per second. The residual elongation was determined after five expansions to 300% and after a recovery time of 60 seconds. The measurement of heat distortion temperature (HDT), hot tear time (HRZ) or hot water voltage drop (HWSA) takes place according to methods described in man-made fibers / textile industry, January 1978, issue 1178, 28.180. Vintage are described on pages 44 to 49. Corresponding information can also be found in DE-A-25 42 500 (1975).

The spinning was carried out after the dry spinning process according to the examples under the following conditions: Shaft temperature 200 ° C Air temperature 220 ° C Air volume 40 m ³ / h jet 12 holes, diameter 0.3 mm Spin head temperature 80 ° C Air swirl nozzle 0.6 bar Deduction of godets 1, 2, 3 325/340/340 m / min

Examples Example 1 (NCO prepolymer solution for Examples 3, 4, 5, 7 and 8)

25,000 g of a polyester diol with a molecular weight M _n = 2,014 based on adipic acid, 1,6-hexanediol and neopentyl glycol (mol ratio of the diols 65:35) were mixed with 13,175 g dimethylacetamide and 5,741 g diphenylmethane-4,4'-diisocyanate ( Desmodur® 44 / Bayer AG). The mixture was then heated to 50 ° C. for 40 minutes until the NCO content of the NCO prepolymer was 2.60%. The solids content of the NCO prepolymer solution was 70%.

Example 2 (NCO prepolymer solution for Examples 6 and 9)

18,000 g of a polyester diol (based on adipic acid, 1,6-hexanediol, 1,4-butanediol, neopentyl glycol; molar ratio of the diols: 64:17:19) with a molecular weight M _n of 3,313 and 7,714 g of a polytetramethylene ether diol (Terathane® 2,000, Du Pont, M _n of 2,066) were mixed with 12,857 g of dimethylacetamide and 4,286 g of diphenylmethane-4,4'-diisocyanate were added. The mixture was then heated to 50 ° C. for 60 minutes until the NCO content of the NCO prepolymer was 2.14% (based on solids). The solids content of the NCO prepolymer solution was 70%.

Example 3 (comparative test carbamate method) to Examples 7 and 8)

60 g of CO _{2 were} added to a mixture of 26 g of ethylenediamine, 1.6 g of diethylamine and 4,463 g of dimethylacetamide. 2,000 g of the NCO prepolymer solution from Example 1 were added to this freshly prepared carbamate suspension with vigorous stirring within 15 minutes. A clear solution with an elastomer solids content of 22% and a solution viscosity of 39 Pa.s / 20 ° C. is obtained. The inherent viscosity was 1.06 dllg. To this viscous elastomer solution, based on polyurethane solids, 0.3 wt .-% Mg stearate 1 wt .-% Cyanox _® 1790 (American Cyanamid, USA), 0.5 wt .-% Tinuvin 622 (Ciba- Geigy) 7 ppm Makrolex® - Violett B (Bayer AG), 0.5% by weight of the polyether siloxane Silvet® L7607 (a polyether / polydimethylsiloxane copolymer, supplied by Union Carbide Corp., USA). 3,000 g of this polymer solution were spun using the dry spinning process.

The solution was spun using the dry spinning method via a 12-hole nozzle with holes from 0.3 mm diameter each. Shaft heating temp. 200 ° C, air temperature 220 ° C, trigger speed 340 mlmin using an air swirler. The textile data are in table 1 and the long-term viscosity behavior is in table 2 summarized.

Example 4 (comparison to Example 7)

60 g of CO _{2 were} added to a mixture of 26 g of ethylenediamine, 1.6 g of diethylamine and 2,732 g of dimethylacetamide. 2,000 g of the NCO prepolymer solution according to Example 1 were added to this carbamate suspension with stirring within 15 minutes. A clear elastomer solution with an elastomer solids content of 30% by weight and a solution viscosity of 121 Pa.s / 50 ° C. is obtained. The inherent viscosity was 1.24 dl / g. Additives as described in Example 3 were added to this viscous elastomer solution. It was spun analogously to Example 3 using the dry spinning process. The data of the threads obtained are shown in Table 1 and the long-term viscosity behavior is shown in Table 2.

Example 5 (comparison to Example 8)

60 g of CO _{2 were} added to a mixture of 26 g of ethylenediamine, 1.6 g of diethylamine and 2,052 g of dimethylacetamide. 2,000 g of the NCO prepolymer solution according to Example 1 were added to this carbamate suspension with stirring within 15 minutes. A clear, elastomer solution with an elastomer solids content of 35% by weight and a solution viscosity of 158 Pa.s / 50 ° C. is obtained. The inherent viscosity was 0.99 dl / g. Additives as described in Example 3 were added to this viscous elastomer solution and it was spun analogously. The data of the threads obtained are shown in Table 1 and the long-term viscosity behavior is shown in Table 2.

Example 6 (comparison to Example 9)

60 g of CO _{2 were} added to a mixture of 21.7 ethylenediamine, 4,445 g of dimethylacetamide and 1.4 g of diethylamine. 2,000 g of the NCO prepolymer solution according to Example 2 were added to this carbamate suspension with vigorous stirring within 15 minutes. A clear elastomer solution with an elastomer solids content of 22% by weight and a solution viscosity of 61 Pa.s / 20 ° C. is obtained. The inherent viscosity was 1.38 dllg. The additives as described in Example 3 were added to this viscous elastomer solution. It was spun using the dry spinning process. (Data of the threads in Tab. 1).

Example 7

3 and using the 2 was a multi-stage nozzle reactor according to FIG Elastomer solution with a solids content of 30% by weight produced.

394,8 Teile Ethylendiamin

24,6 " Diethylamin

17.430,0 " Dimethylacetamid

53.5 parts of the NCO prepolymer solution diluted to 39.2% by weight and prepared according to Example 1 were placed in container 3 and 17.8 parts of amine solution in container 4. The amine solution had the following composition:

394.8 parts ethylenediamine

24.6 "diethylamine

17,430.0 "dimethylacetamide

The diameter of the fabric nozzle 1 and the mixing nozzle 2 (s. Fig. 2) was 0.5 mm and 0.75 mm. The diameter of the Holes in the homogenizing nozzle 0.75 mm. The NCO prepolymer solution was the nozzle reactor with a form of 25 bar and a mass flow of 45 kg / h and the Amine solution with a pre-pressure of 28 bar and a mass flow of 15 kg / h using the metering pumps 5 and 6 fed. The residence time in the mixing zone was approx. 0.5 to 5 ms. Then the reaction solution got into the Post-reaction part, in which they for post-reaction 50 ° C was heated with the heat exchanger 16. The gear pump 12 moved the mass flow at 90 kg / h and promoted 30 kg / h in the heat exchanger and 60 kg / h from the Post-reaction part. Then the finished, clear, homogeneous and gel-free elastomer solution with the discharge pump 13 promoted from the device. The elastomer solution has an elastomer solids content of 30% by weight and a solution viscosity of only 56 Pa.s / 50 ° C. The inherent viscosity was 1.13 dl / g. In this elastomer solution additives were added as in Example 3. The polymer solution was analogous using the dry spinning process spun (data of the fibers are in Tab. 1 and the long-term viscosity behavior shown in Tab. 2).

Examples 8 and 9

Examples 8 and 9 were carried out according to example 7 in the device described there under the same reaction conditions. Table 3 shows the composition of the starting components and the viscosity and the inherent viscosity of the elastomer solutions obtained. Example 8 Example 9 Template container 3: NCO prepolymer with the prepolymer concentration from example 1
45.75% from example 2
28.86% Template container 3 : 45.9 parts 72.8 parts Template container 4 : 15.3 parts 24.3 parts Composition template Container 4: - ethylenediamine 394.8 parts 325.8 parts - diethylamine 24.6 parts 20.3 parts - dimethylacetamide 14,880.0 parts 23,910.8 parts The elastomer solution obtained had the following characteristics: - solids content 35% 22% - viscosity 70 Pa.s / 50 ° C 90 Pa.s / 20 ° C - inherent viscosity (see measurement instructions) 1.01 dl / g 1.32 dl / g

Standzeitverhalten der Elastomerlösungen aus den Beispielen 3, 4, 5, 7, 8 bei 25°C Beispiel Lösungsviskositäten [Pa.s (50°C; in Beispiel 3: 20°C)] 1. 2. 5.Tag ▵ 3 (Vgl.) 38 36 36 - 8 % 4 (Vgl.) 121 159 verpastet 5 (Vgl.) 158 verpastet 7 (erf.gem.) 56 59 64 +14 % 8 (erf.gem.) 70 n.b. 75 + 7 % ▵: Gesamtänderung der Lösungsviskosität in Prozent gegenüber der Ausgangsviskosität
n.b.: nicht bestimmt As described in Example 3, additives were added to the elastomer solutions obtained. They were spun using the dry spinning method analogous to this example. Table 1 summarizes the textile data and Table 2 summarizes the long-term viscosity behavior. It should be particularly pointed out that elastane threads with increased extensibility are obtained by the process according to the invention, which is of particular advantage for a number of application areas.

Service life behavior of the elastomer solutions from Examples 3, 4, 5, 7, 8 at 25 ° C example Solution viscosities [Pa.s (50 ° C; in Example 3: 20 ° C)] 1. 2nd 5th day ▵ 3 (see) 38 36 36 - 8th % 4 (see) 121 159 pasted 5 (see) 158 pasted 7 (in accordance with) 56 59 64 +14% 8 (in accordance with) 70 nb 75 + 7% ▵: Total change in solution viscosity in percent compared to the initial viscosity
nb: not determined

Example 7a Use of a long-term nozzle according to Fig. 1b (not according to the invention)

3 and using a 1b was attempted an elastomer solution with a solids content of 30 wt .-% and with the same recipe as in Example 7.

The diameter of the fabric nozzle 23 was 0.4 mm and Mixing nozzle 24 had two holes with a diameter of 0.6 mm. The NCO prepolymer was first pre-printed of 30 bar and a mass flow of 45 kg / h and the amine solution with a pre-pressure of 35 bar and a Mass flow of 15 kg / h supplied. The dwell time in the mixing zone was approximately 100 ms. After a short drive there were uncontrolled pressure fluctuations up to> 40 bar on that with a swelling of the emerging reaction solution were connected so that the experiment was terminated had to become.

Example 7b Use of a short-time nozzle according to FIG. 1a (not according to the invention)

In the system according to Fig. 3 and using the 1a was tried an elastomer solution with a solids content of 30 wt .-% and with the same recipe as in Example 7.

The diameter of the fabric nozzle 21 was 0.4 mm and Mixing nozzle 22 had a bore of 0.6 mm in diameter. The NCO prepolymer was initially printed on a 20 bar and a mass flow of 45 kg / h and the amine solution with a pre-pressure of 25 bar and a mass flow fed from 15 kg / h. The residence time in the Mixing zone was about 5 ms.

The spinning solution obtained from this contained microgels during the subsequent dry spinning of the spider solution repeated fiber tears.

Claims (15)

1. Continuous process for the production of highly concentrated elastane spinning solutions with improved flow properties and high viscosity stability from fast-reacting polyaddition components, characterized in that the reaction components are continuously metered from the batch containers into a multi-stage nozzle reactor, consisting of a mixing chamber (10) with a substance nozzle (1), a mixing nozzle (2) and a homogenizing nozzle (7) which are connected directly in series, in the first stage of the multi-stage nozzle reactor the reaction components are mixed together in the mixing nozzle (2) of the reactor in up to 10 ms, in a second stage the reacting mixture is homogenized in a homogenizing nozzle (7) and then reacted fully in a downstream reactor.
2. Process according to Claim 1, characterized in that the reaction components are NCO prepolymers and cycloaliphatic or aliphatic diamines and the diamines are fed to the mixing nozzle (2) via a substance nozzle (1).
3. Process according to Claim 2, characterized in that the NCO prepolymers are produced from a) polyester or polyether diols or mixtures of polyester and polyether diols with a molecular weight of 1000 to 8000, diisocyanate c) and optionally low-molecular diols b).
4. Process according to Claim 1 and 2, characterized in that ethylene diamine is used as diamine.
5. Process according to Claims 1-4, characterized in that the reaction solution is fed into an intermediate buffer reactor (11) directly behind the nozzle reactor.
6. Process according to Claim 5, characterized in that a recirculating circuit with a heat exchanger (16) is connected to the intermediate buffer reactor (11).
7. Process according to Claim 6, characterized in that the viscosity in the recirculating circuit is kept constant in that the viscosity in the recirculating circuit is measured and is used as control variable for the metering of the reaction components.
8. Process according to Claims 1 to 7, characterized in than the residence time of the reactants in the reactor up to the end of the mixing nozzle (2) is from 0.1 to 5 ms.
9. Gel-free polyurethane urea elastomer spinning solutions obtainable by the process according to one of Claims 1-8 with a viscosity of 10-350 Pa.s measured at 50 °C and a shear rate of 23 s^-1, characterized in that they have a solids concentration of > 30 wt.% and a viscosity stability of at least +/- 20% when stored at 50°C for at least five days.
10. Spinning solutions according to Claim 9 produced by the process according to Claims 1-8.
11. Fibres or filaments, produced from spinning solutions according to Claims 9 to 10.
12. Multi-stage nozzle reactor for implementing the process according to one of Claims 1-8, consisting of a mixing chamber (10) with a substance nozzle (1), a mixing nozzle (2) and a homogenizing nozzle (7) which are connected directly in series, characterized in that the residence time of the reaction components which flow into the reactor and of which one is fed via the substance nozzle (1) and further reactants via the mixing chamber (10) is ≤ 10 ms up to complete mixing at the end of the mixing nozzle (2) and in that back-mixing is avoided in the region of the mixing chamber (10) between the substance nozzle (1) and the mixing nozzle (2).
13. Multi-stage nozzle reactor according to Claim 12, characterized in that substance nozzle (1) and mixing nozzle (2) are axially connected in series and a torpedo (9) which guides the reaction mixtures to the holes (8) of the homogenizing nozzle (7) adjoins the mixing nozzle (2) in front of the homogenizing nozzle (7).
14. Multi-stage nozzle reactor according to Claims 12 and 13, characterized in that the residence time of the reaction components in the mixing chamber (10) up to the end of the mixing nozzle (2) is ≤ 10 ms.
15. Multi-stage nozzle reactor according to Claim 14, characterized in that the residence time of the reaction components is from 0.1 to 5 ms.

Images