DE1570969A1 - Process for the production of fiber-forming polyurethane elastomers - Google Patents

Description

DR. E. WIEGAND 8000 MÖNCHEN 15, 13th M df 1965

MUNICH NUSSBAUMSTRASSE 10

D [PL.-1NG. W. NIEMANN phone: 555476

HAMBURG
FATINTANWKlTi

W. 12208/65 9 / Hir

Monsanto. Company, St. Louis, Missouri (V.St.l.)

Process for the manufacture of / fiber-forming Polyurethane elastomers.

The invention relates to a process for the production of elastomeric polymers. In particular, the invention is directed to a continuous process for the manufacture of fiber-forming Polyurethane elastomers made from polymeric glycols and organic diisocyanates ^

Polymers of this general type have recently found widespread use in manufacturing found of elastic fibers and threads. So far, we-n Polyurethane elastomers made by using a polymer

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Dlyool and organic diisooyanate were introduced into a reactor and the reaction participants were intimately mixed with one another until the glycol old isocyanate radicals ended and was "capped" in order to obtain a copolymer with old ionooyanate end groups. The Torpolyaerisat is then removed from the reactor, whereupon a further batch of fieaktionateilnehBern is introduced into the leactor The Yorpolymerieate are subsequently reacted in a second reactor with a chain extending agent (chain extending agent) to form urethane polymer IU, whereupon the polymer from the second Reactor is removed and then a further batch of the Torpolymerisats is introduced into the second reactor in order to react it in a corresponding manner with the chain extension agent. 'S' it can be seen that this type of procedure is normally referred to as a sentence-wise procedure ( ^N bateh ^N prooess).

The term "polyurethane elastomers" as used herein is intended to mean elastomeric copolymers Clay polyurethane, e.g., elastomeric polyurethane-polyurea copolymers.

Although polyurethane elastomers made in this manner have generally been satisfactory an inherent basic laughing part of everyone

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aatsweisca procedure in a lack of uniformity and uniformity of the end products. Si · uniformity can be effectively controlled when the reaction is carried out in a continuous manner, but it was bilker says sohwiorlg, if not impossible, Producing polyurethane elastomers in an efficient, practical continuous process, and was because of. the very high viscosity of the prepolymer with isoojanate groups. This high viscous Torpolymerisat Terhindort not only a correct · and impeccable loss, but also a steady flow in a continuously operating device. Such an uneven flow does not only lead to the following an uneven product, but also easily results in frequent interruptions or plant closures in a continuous process.

^The purpose of the invention is to create a novel continuous process for the production of fiber-forming polyurethane elastomers. Another aim is the creation of a continuous process but the production of fiber-forming polyurethane elastomers of uniform and superior quality. Another Koch purpose is to create a continuous process

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for the production of fiber-forming polyurethane elastomers in an effective and economically practical arrangement. Other purposes and advantages will be apparent from the discussion below.

The method according to the invention generally comprises the following operations: Continuous Supplying a polymeric glycol, an organic diisocyanate and a solvent which is a solvent for the glycol, for the diisocyanate and the prepolymer product and with these materials unresponsive to a reaction zone at a predetermined controlled rate; the reaction zone becomes kept essentially free of substances other than reactants, prepolymer and solvent; continuous deduction of the in this Formed manner capped with isocyanate groups Prepolymer from the reaction zone and introducing it at a controlled rate into a polymerization zone; continuous supply of a chain extender to the polymerization zone at a predetermined regulated rate; and continuous withdrawal of urethane polymer from the polymerization zone. The tJrethane polymer can then be stored or continuously fed to a suitable device in which the polymer is processed into Pfiden.

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The method according to the invention is as follows further explained in connection with the flow diagram of the accompanying drawing. Polymeric glycol found in a suitable solvent can be dissolved, is from a supply source 1 through a line 3 and a measuring pump 5 is fed to a reactor 7. At the same time and in essentially stoichiometric amounts Diisoeyanat, which is also in a suitable solvent can be solved, fed from a source 2 through a line 4 and a measuring pump 6 into the heater 7. Although the solvent is in the form of a separate feed stream from a separate source (not shown) can be added, it has been found more effective to add one or both of the reactants in the form of a solution in the solvent to feed. In some cases it can be advantageous to use the reactor contents for the formation of the prepolymer to keep moving or to stir} in this case the reactor 7 is equipped with a stirrer 8, the latter is driven by a motor 9. The design of the reactor must be chosen so that the possibility the presence of substances other than the respondents, the prepolymer and the solvent is eliminated. This has proven necessary

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since air and moisture cause the formation of impurities and their presence must be avoided. It was found that a blanket with inert gas, as is normally used to exclude moisture and air from the reaction zone is applied, the formation of polymeric skins on the liquid surface supports. Since the running time of continuous polymerization is long, any Formation of an impurity, even if it is formed to a small extent and at a slow rate, a premature interruption and suspension of the proceedings cause and must therefore be avoided. The reactor 7 is shown schematically in the 3-phase diagram, that he is on the ground through lines 3 and 4 is charged and the prepolymer formed is discharged at the top through a line 10. Such a one Training has been found to be suitable for the purposes of the method according to the invention, since at Using a reactor of this design the prepolymer is not discharged until the reactor is completely filled by the reactants entering and the prepolymer formed therefrom. In this way the possibility of the presence of other substances is eliminated. However, you can also

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other constructions can be used as long as the need for an inert gas cover is avoided.

Yorpolyeerisat that formed in the reactor 7 has been, is passed through the line 10 and a hot pump into a PolymerisationsbehSlter 14-, namely simultaneously with a measured amount of a chain extender from a source 12 through a Line 15 and a let pump 13 · The polymerization vessel 14 is equipped with a stirrer 18 which is driven by a motor 19. The polyurethane product is withdrawn through line 20 and can to a storage tank 21 or it can be fed directly to a suitable device (not shown) for the production of polyurethane threads.

In addition, it has proven to be particularly desirable proven to continue the evenness of the product through. Regulation of the feed rate into the polymerization tank 14 to regulate to minor changes to compensate, which are caused by slightly changing conditions, as they can occur in reactor 7, result. According to this embodiment of the invention the extent of introduction of either prepolymer or chain extender into the polymerization vessel depending on and in response to measured

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Changes in viscosity of the material in the polymerization "tank varies. For this purpose, the polymerization vessel 14 can be equipped with a viscosity measuring device 16 , the latter can be designed so that it generates a signal which is amplified and through

a line 17 to the measuring pump 11 or to the measuring pump 13 can be performed to regulate their operation. When using a device δπΗ? this is done automatically Changes in the amount of prepolymer or chain extender in response to changes in viscosity resulting in a more uniform polymer product results.

The method according to the invention is not limited to any specific reactants. On the contrary, one of the technically advantageous features of the process according to the invention is that the process for making polyurethane elastomers from any of the conventional starting materials can be used, for example those described in US Pat. No. 5,115,384. So comes in the process according to the invention, the use of polyether glycols, such as polyalkylene ether glycols, polyalkylene arylene ether glycols, polyalkylene ether thioether glycols (polyalkylene ether thioether glycols) and polyester olycols, including polyester glycols derived from caprolactones , in

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Consider, The same general observation applies to the wide range of starting materials in relation to the organic diisocyanates used in the process according to the invention for reaction with the polymeric glycol can be used. The method according to the invention is not in any specific way of diisocyanates ", rather any of the numerous diisocyanates noted in the art can be used in the method according to the invention. These substances are also in the field known, so that a repetition is superfluous at this point; for example see the USA patent 2,871,227 and the United States patent referenced above pointed «In the technical implementation it was found that the preferred diisocyanate 4-, 4 -'-diphenylmethane diisocyanate is.

The chain extenders are also known in the art as compounds that are not have more than two atoms that carry accessible active hydrogen atoms. The term "active hydrogen atoms "refers to hydrogen atoms which, as a result of their position in a molecule, have activity in the Zerewitinoff tea, as described by Kohler in J. Am. Ghem. Sac. 49 »5181 (1927), Beigen. Here too is a new enumeration of all usable chain

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• Extension means not required} for example refer to the patents listed above. Preferred chain extenders are 1,3-benzene-bis (methylamine), ethylenediamine, propanediamine and hydrazine. The publications mentioned above are hereby incorporated by reference.

As previously indicated, it has been found that by reacting the polymeric glycol and the organic diisocyanate in a solution, the process can be carried out in a continuous manner since, in doing so, the viscosity of the system at this stage of the process is low enough to permit one to allow the continuous process to operate effectively. Any solvent can be used which is a solvent to the glycol, diisocyanate and prepolymer product and which will not react with these materials under the reaction conditions used in the process. Examples of suitable solvents are dimethylformamide, dimethylacetamide, dimethylpropionamide, dimethylsulfoxide, etc. For purposes of the invention, dimethylacetamide and dimethylformamide are the preferred solvents. As mentioned above, for maximum effectiveness, a solution will be prepared by one or both of the participants prior to introduction to the session, albeit

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the solvent can be introduced into the reactor in the form of a separate stream, so either the polymeric glycol is the reactor in the form of a Solution added, or the organic diisocyanate is dissolved in a solvent and this solution becomes introduced into the reaction zone, or both reactants are introduced as solutions. Goal in part both the glycol and the diisocyanate are added to the reaction zone in the form of separate solutions admitted.

The temperature maintained in the reactor and the polymerization vessel is not critical. Usually, once the reaction between the polymeric glycol and the diisocyanate has begun, enough exothermic heat of reaction will be given off to maintain a continuous reaction. Although temperatures as high as 90 -. 100 ⁰ C can be used in the Vorpolymerisatreaktor, it was found that at these high temperatures a strong tendency to form impurities, etc. as lllophonat, is what, if possible, to avoid is . Accordingly, the temperature of the prepolymer reaction is preferably maintained between about 25 ° and about 40 ⁰ C. The temperature of the polymerization tank can be convenient

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and suitably kept at approximately the same temperatures will.

The one in the reactor or the polymerization tank Maintained pressure is not critical and it can be atmospheric, sub-atmospheric, and super-atmospheric Pressures are applied. Usually the reaction between the glycol and the diisocyanate is carried out at atmospheric pressure. Although the reaction between the prepolymer and the chain extender are carried out in a satisfactory manner at atmospheric pressure Generally, a head of pressure of between about 0.5 and about 1.1 atmospheres (8-15 psig) will result the continuous nature of the process in the polymerization vessel.

The rate or speed (amount / time) at which the reactants are introduced into the reactor is, of course, determined by the desired residence time in the reactor and the desired molar ratio of the reactants is determined. The residence time or residence time in the reactor is in turn dependent on various factors. The higher the reaction temperature used, the shorter the required Be response time. As stated above, however, high temperatures should avoid the formation of impurities increase, be avoided. The response time will too

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influenced by the use of catalysts. In the process according to the invention, any of the known and conventionally used catalysts can be used in the reaction between the polymeric glycol and the organic diisocyanate. However, it has been found that basic dibutyltin acetate and dibutyltin dilaurate are particularly advantageous when the reaction is carried out in solution because of their stability in the solvent. Using these catalysts, a further reduction in the amount of undesirable impurities such as allophonate formed can be observed. In any case, the prepolymer should be withdrawn from the reactor prior to any significant gel formation. In general, the prepolymer compositions (prepolymer dopes) produced by the process according to the invention are stable for several hours and accordingly no gelation occurs in the reactor. It can be seen that any significant gelation would adversely affect the continuity of the process and should be avoided. Within the scope of the variables listed above, it has been found that the residence time in the reactor can range anywhere from 30 minutes to 4 hours. The most convenient and preferred time

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is 1 hour.

The reactants are introduced into the reactor at such a rate that the desired residence time therein is brought about and a constant molar ratio is also created between the reactants. It has been found that the best results are obtained when the molar ratio is essentially stoichiometric. The stoichiometric ratio for the reaction between the polymeric glycol and the organic diisocyanate is 2 moles of diisocyanate per mole of glycol. "Essentially stoichiometric" is to be understood as meaning a ratio between 1.9 mol and 2.1 mol of diisocyanate per mol of glycol, ie a change of 10 % is possible. However, it is important, regardless of the ratio employed, that the feed be introduced at a constant rate as any changes in the feed rate will affect the uniformity of the final product.

In general, the chain extender can be added to the prepolymer in a stoichiometric amount i.e. about 1 mole of chain extender for each mole of prepolymer, however, in order to avoid one Cross-linking required, enough chain extender to react with all free isocyanate groups to be used, i.e. at least one chemical equivalent

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of diamine groups to I so cyanate groups. · The reason for this consists in the fact that free isocyanate groups are able to attack the urea bonds formed in order to bring about a cross-linking. Cross-linked polymers are infusible and insoluble and can accordingly not be extruded into thread structures. Accordingly, the chain extender is generally used in Amounts slightly larger than the stoichiometric amount added. It can be seen that the exact amount of chain extender added to the prepolymer of that employed in the reaction between the polymeric glycol and the organic diisocyanate nolarexi ratio and continues on the amount of no unoccupied reaction participants in the polymer ion container enter, will depend. This has its The reason is that whenever other than precisely stoichiometric ratios are used in the initial reaction or the initial reaction does not proceed to completion, an excess of one of the reaction participants will be in the system at the point where the addition of the chain extender is made. It is hence, in general, it is desirable to adjust the rate of addition of the chain extender to the rate at which the polymeric glycol and the organic diisocyanate to the

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Reactor are to be adjusted, so that essentially a mole or slightly more of chain extension agent for every mole of prepolymer formed in the reactor is added to the system. The chain extender can also be introduced in the form of a solution and such an approach is preferred. It is generally preferable to use the same solvent as used in the initial reaction. However, other solvents can also be used can be used as long as they are solvents for the chain extender and that polyurethane polymers are used represent under the conditions used and do not react with these materials.

When carrying out the process according to the invention, it was found that the prepolymer, which leaves the reactor and enters the polymerization vessel, not always exactly the same composition Has. This is due to slightly variable conditions in the reactor, which is the inevitable result of operating a continuous apparatus of this type. Because the production of a uniform product represents one of the purposes of performing the method according to the invention, it has been found to be or proved necessary, the feed rate in the polymerization tank in accordance with this change in the

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Composition of the prepolymer masses leaving the reactor to varyj the latter is indicated by a change in the viscosity of the contents of the polymerization vessel. As mentioned above, there is one particularly expedient embodiment of the invention is such a state by applying a Compensate viscosity meter, which is maintaining a relatively constant Viscosity in the polymerization vessel enables · line such equipment can be independent of the actual Viscosity of the contents of the polymerization tank be used. For example, if it becomes necessary to produce a polymer that can be used in a The dry spinning process is to be used is a highly viscous polymer, e.g. from 75,000 - 100,000 cps, required, while a polymer of lower viscosity, e.g. 20,000 - 30,000 cps, is required, when the polymer is to be wet-spun. In the method according to the invention, both types of Polymer are generated and these have more uniform properties as a result of the application of the above Viscosity measuring device. This facility is on the polymerization vessel in such a manner attached that they reduce the viscosity of the contained therein

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Polymer solution continuously BiBt. When see the Viscosity of the polymer in any noteworthy. If the extent changes, the viscometer gives a The indicator for the change and the charge to the polymerization vessel is adjusted to compensate for this change. You can adjust automatically take place} in this case a signal τοη of the Viekositätsmeßeinriehtung is emitted and this signal can amplified and then transmitted to the hot pump, through which the prepolymer in its path τοη the leak tor goes to the polymerization tank, or to the let pump through which the chain extender is introduced into the polymerization vessel · through Operation of the method with such a device the evenness of the end product is greatly increased. Although the device can be designed so that If it transmits a signal to one or both of the reactants entering, it has proven advantageous to feed in what is coming from the reactor Regulate prepolymer xu and the supply of the chain extension agent at a constant predetermined Keep rate au.

The method according to the invention is easy to the production of polyurethanes that contain stabilizers or matting agents such as titanium dioxide.

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fit. These and any others you want Additives can be introduced into the process at any point where their addition is compatible with the system is.

The invention is illustrated below by way of examples further explained, however, it is not limited thereto and any of the above may be the modifications presented with comparable results be made.

example 1

In the bottom of a glass reactor about 76 mm (3 inches) in diameter and about 152 mm (6 inches) long, having a volume of about 800 cm *, a dineth-lformanide solution containing a mixture of 50 parts of polyethylene adipate was introduced and 20 parts of polypropylene adipate in a ratio of about 1 part of dimethylformamide to 2 parts of glycol by weight. At the same time, a solution of 1 part 4,4'-diphenylmethane and 1 part dimethylformamide, based on the weight, was fed in at the bottom of the reactor was passed at a level of 3 »9 g / min. the reactor was stirred and the temperature was maintained at about 31 ⁰ C. the Verweilseit in the Beak-

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tor was about 1 hour. Prepolymer was continuously withdrawn from the top of the reactor and introduced into the bottom of a polymerization vessel by a hot pump. The polymerization vessel was designed similarly to the reactor. A solution of 1.53 parts by weight of 1,3-benzene-bis (methylamine) in 100 parts by weight of dimethylformamide was simultaneously added to the polymerization vessel at a rate of 33.8 g / min. The contents of the polymerization vessel were continuously stirred and the temperature was kept at about 28 ^° C. The viscosity of the polymer was measured continuously by a viscosity measuring device connected to the polymerization vessel; this was designed in such a way that it responded to changes in viscosity by automatically regulating the flow of prepolymer coming from the reactor. Polyurethane polymer was continuously sucked out of the polymerization vessel and passed into a storage tank. The polyurethane polymer was then spun into a 300 denier yarn; this had a tencity of 0.5 g / denier and an elongation of 530%.

The procedure of Example 1 was repeated with the exception that 1,3-propanediamine was used in place of

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1,3-Be: azole-bi3 (methylamine) was used. This enhancement means (Extender) was in a solution of dimethylformamide containing 0.87 parts by weight of diamine each Containing 100 parts by weight of dimethylformamide was added. The diamine was in a polymerization tank Rate of 25 »6 g / min fed. Yarn made from this Polymer was spun, had a strength of 0.62 g / denier and an elongation of 600%.

Example 3

The procedure of Example 1 was repeated with the exception that the polymeric glycol was a copolymer was used, that of 80 parts by weight

£ -caprolactone and 20 parts by weight of E-methyl- £> capro-1actone was derived using "diethylene glycol" initiator in dimethylformamide. The glycol was ^{fed at a rate of 9.5 2} l-g / min and the diisocyanate was in a Rate of 3.25 g / min fed in. Yarn which was spun from this polymer had a tenacity of 0.556 g / denier and an elongation of 515 %.

Example 4-

The procedure of Example 1 was repeated except that the dimethylfoamamide solvent was replaced by dimethylacetamide. The amount of solution medium was the same for the glycol solution, the diiso-

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oyanate solution and the diamine solution. Yarn that out the β tu polymer was spun, was that in Example 1 produced yarn very similar.

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Claims (1)

T570969 Claims 1. Process for the production of fiber-forming Polyurethane elastomers, characterized in that. a polymeric glycol and an organic diisocyanate all respondents with predetermined regulated Asked and a solvent, dae with the glycol, the Diisooyanate and the prepolymer product formed by their reaction do not react, however, these materials solves, continuously introduces into a Seaktionssone, the reaction zone is essentially free of others Substances as the reactants, the solvent and the Torpolymerisat holds, continuously withdrawing formed prepolymer from the Seaktionszone and continuously passing this polymerizate at a predetermined controlled rate into a polymerization zone, the ingredients of the polymerization zone intimately Termiecht and continuously withdraws fiber-forming polyurethane elastomer from the polymerization zone. 2. The method according to claim 1, characterized in that at least one of the reactants 009820 /! 597 "β", in f ο im introduces a solution into the solvent. 3. The method according to claim 1 or 2, characterized in that one introduces the polymeric glycol and the organic Diieooyanat in the form of a solution in the solvent and the Bate of the introduction of the leaction participants is selected so that the molar ratio of glycol to diisocyanate is essentially stoichiometric. 4. The method according to any one of claims 1-3 » characterized in that separate solutions of the polymeric glycol and the organic diisocyanate in a solvent prepares the glycol solution and the Diisocyanatesung separately in a regulated hatch introduces into the heating zone, so that a substantially stoehiometric molar ratio of glycol to Diieocyanate is brought about, and in the polymerization zone continuously a Xette extending agent in one Sate regulated in such a way that a small stoichiometric excess τοη Eettenerweitermittel to prepolymer is present. 5 «method according to one of claims 1-4, characterized in that the extent of the introduction of at least one of the polymer! sation zone introduced materials depending on and in response to viscose! 009820/1597 the polymerization zone varies, 6 · Process according to one of claims 1 - 5 »characterized in that the solvent Dimethylaeetamide or dimethylformamide and a diamine is used as a chain extension agent. 7. Procedure in accordance with one of »the inspections 1-6, characterized in that the viscosity of the contents of the polymerisation zone is measured continuously and the rate of supplying the prepolymer to the polymerization zone in response to observed changes in viscosity of the contents of the polymerization zone varies 8. The method according to any one of claims 1-7 »characterized in that the temperature of the reaction zone between about 25 ° and about 40 ⁰ O is kept. 9. The method according to any one of claims 1-8, characterized in that the Diaain Brweitermittel (extender) as a solution of diamine in Diaethylacetamid in an amount which is at least sufficient to to provide one mole of diamine per mole of prepolymer, introduces. bad 0 0 9 8 2 0/1597 Blank page