MXPA99005028A - Procedure for the manufacture of polyisocianates containing iminooxadiazindiona groups, the products of the procedure so manufactured and their - Google Patents

Abstract

The present invention relates to: The invention relates to a process for the manufacture of polyisocyanates with at least 30 mol% of iminooxadiazinedione asymmetric trimers groups), based on the total amount of isocyanurate and iminooxadiazinedione groups, by catalytically induced trimerization - organic polyisocyanates with a molecular weight (average) of 14-600 g / mol with isocyanate groups linked aliphatically, cycloaliphatically and / or araliphatically, independent of each other, characterized in that ammonium fluorides or quaternary phosphonium of the formula are used as trimerization catalyst ( I) in which E represents N or P and R represents aliphatic, optionally branched, aromatic and / or araliphatic moieties, the same or different, two or more R substituents can also form together with nitrogen or phosphorus saturated or unsaturated cycles, in which the catalyst is present in the pure form, ii) mixed with agents of S solvation for the fluoride anion, where S can be a pure compound or a mixture of different substances from the group of protic compounds with a pKa value greater than 2 (determined in H2O at 25 ° C) and oxalic acid, but no functionalization alcohol higher (di- or polyol) or HF, with the proviso that the molar ratio of S to fluoride ion (F) does not exceed the value of 20, iii) mixed with water, where the molar ratio of water to fluoride ions ( F) do not exceed

Description

PROCEDURE FOR THE MANUFACTURE OF PCLIISOCIANATOS CONTAINING GROUPS IMINOOXADIAZIDIONA, THE PRODUCTS OF THE PROCEDURE SO MANUFACTURED AND SO USE FIELD OF THE INVENTION.

The invention relates to a process for the manufacture of polyisocyanates containing iminooxadiazinedione groups, to the process products thus manufactured and to their use.

DESCRIPTION OF THE PREVIOUS TECHNIQUE The polyisocyanates containing amideoxadiazmione groups (asymmetric trimers) are very valuable raw materials among other things for the production of polyurethane coatings and coatings (DE-A 19 611 849). These are, certainly only as subcomponents, a usual companion of the isocyanurates (trimeres símemeos) known for some time.

The isocyanate cligomerics with a Ref .: 30444 significantly high content of iminooxadiazinedione are subject of the "oldest application" (DE-A 19 611 849) in which its advantageous properties are also described in detail, for example as a raw material for the manufacture of polyurethane lacquers and coatings Thus, the polusocyanates containing moxadiazdione groups are the oligomers of at least trifunctional (di) isocyanate in NCO of lower viscosity.

DE-A 19 611 849 proposes very general hydrogens (poly) fluorides of the general formula. { M [nF ~ * (HF)]} , where m / n > O and M is a charge cation n or a n-valent moiety, as a catalyst for the trimeation of isocyanates with preferred formation of immooxadiazinedione groups.

This method of procedure, however, suffers from the disadvantage that for the preparation of the catalysts, which is generally carried out from the corresponding fluorides. { M [nF ~]} / where M represents a n-charge cation, HF must be used. This last circumstance limits the practicability of the whole procedure, since for the handling of the, given the anhydrous case, fluoride of rcaenc on the one hand, special protection measures are required which make the preparation of the catalyst very expensive and on the other hand, due to the corrosiveness of the material, certain requirements result in the choice of reactors in which the catalyst can be prepared and used.

These circumstances prevent a broad and safe realization of the process of isocyanate trimeation with partial formation of iminooxadidiazdione groups.

It has therefore been the object of the invention to provide a process which, on the one hand, is characterized in that, for the preparation of the catalysts, hydrogen fluoride must not be handled and, on the other hand, products with a high content of ammooxadiazamione groups in the mixture of trimers (the term "trimer mixture" is always referred to the sum of isocyanurate and iminooxadiazmione). A high content of ammooxadiazinedione groups means, in the sense of the present invention, products with at least 30% of the ammooxadiazinedione groups in the mixture of trimers.

This task could be solved by the procedure described below, in which the trimerization is catalyzed by ammonium fluorides or quaternary phosphonium.

BRIEF DESCRIPTION OF THE INVENTION The subject of the invention is a process for the production of polyisocyanates containing at least 30 * mol of iminooxadiazinedione groups (asymmetric trimers) in the mixture of trimers by catalytically induced trimerization of organic di- or polyisocyanates with a molecular weight (average) of 140-600 g / mol with isocyanate groups linked aliphatically, cycloaliphatically and / or araliphatically, independent of each other, characterized in that ammonium fluorides as well as quaternary phosphonium of formula are used as trimerization catalyst.

R, E "F" ÍI) wherein E represents N or P and R represents aliphatic radicals, optionally branched, aromatic and / or araliphatic, identical or different and optionally two or more R substituents can also form with each other and with the nitrogen or phosphorus atom saturated or unsaturated cycles, in which the catalysts are i) present in pure form, ii) mixed with solvation agents S for the fluoride anion, where S can be a pure compound or a mixture of different substances from the group of protic compounds with a pKa value greater than 2. (determined in H: 0 to 25 ° C) as well as oxalic acid, but no alcohol of superior functionalization (di- or polyol) or HF, with the proviso that the molar ratio of S to fluoride ion F "does not exceed the value of 20, or iii) mixed with water, where the molar ratio of water to fluoride ions (F ~) does not exceed the value of 10.

DESCRIPTION OF THE INVENTION Preferably, in the process according to the invention, as the isocyanate component to be trimerised, aliphatic diisocyanates of a molecular weight (range) of 140-300 g / mol are used as pure compounds or as discrete mixtures with each other.

The products of the process preferably have a content of at least 35%, more preferably at least 40% by mole, of iminooxadiazidione groups (asymmetric trimers).

As the trimerization catalyst, preference is given to using ammonium or quaternary phosphonium fluorides of the formula (I) mixed with monofunctional alcohols (or mixtures of) of a molecular weight (average) in the range of 32-250 g / mol, not exceeding concentration of the ammonium fluoride or quaternary phosphonium 20% by weight, particularly preferably 30 * by weight, in the mixture.

Another object of the invention is the above-described process, characterized in that ammonium or quaternary phosphonium fluorides of formula (I) mixed with organic acids with a pKa value greater than 2 (determined in H 0 to 25 ') are used as the trimerization catalyst. C) as well as oxalic acid, not exceeding the molar ratio of organic acid to fluoride ion, F ", the value of 10, preferably 5, with particular preference 2.

Another object of the invention is the above-described process, characterized in that ammonium or quaternary phosphonium fluorides of formula (I) are used as a trimatization catalyst mixed with water, the molar ratio of water to fluoride ion (F ") not exceeding the value of 10, preferably 5.

Finally, it is also the object of the invention to use the products manufactured according to the method according to the invention.

The type and degree of solvation of the fluoride anions are of essential significance in the invention for carrying out the process described herein.

An essential feature of the invention of the method presented is the use of the catalyst tetraalkylphosphonium fluoride or ammonium in the trimerization as concentrated as possible even by dosing it as practically pure active substance. This is limited in practice by the requirements of the technical handling of the catalyst. Thus, the solubility or rapid homogeneous distribution, for example, of solid catalysts or highly concentrated and sometimes very viscous catalyst solutions in the (poly) isocyanate (or mixture) is sometimes too low to avoid spontaneous formation of gel particles. consequence of local over-contracts.

In this context it is therefore necessary to mention an essential property of S: the complexing properties of S for the fluoride ion must be such that at least up to the homogeneous distribution in the (poly) isocyanate (or mixture) to trimerize a slow display of the catalytic activity of the fluoride anion (slow release mechanism, for its acronym in English "slow reléase") is established. Otherwise this can lead to the formation of spontaneous over-tethering that leads to the formation of unusable turbidity products. This can be counteracted by diluting the catalyst, as has surprisingly been found, but in this way the proportion of iminooxadiazinedione in the trimer mixture is reduced to the same extent (see Example 4).

Thus, the use of liquid tetraalkylphosphonium or ammonium fluorides as the trimerization catalyst is especially preferred. However, they can also be used as solid pure substance but with addition of very small amounts of liquid S compounds such as for example tetrabutylammonium fluoride or tetrabutylphosphonium.

In principle, with the same good results, pure compounds or discrete mixtures of compounds of empirical formula RE + F "can be used in which E represents N or P and R represents identical or different radicals, optionally branched, optionally substituted, aliphatic, aromatic and / or araliphatic Ci-C ... can be purchased commercially at least in the form of their salts with other counterions than the fluoride ion, but which can easily be transformed into the fluoride form, for example chlorides, bromides, iodides, (hydrogen) sulfates; see among others J. Org. Chem. 1989, 54, pgs. 4827-4829, as well as Synthesis 1988, 12, pgs. 953-5 and Example 1, for example the tetrakis (hydroxymethyl) phosphonium chloride and sulfate, the chloride, bromide and / or iodide of tetraethyl, tetrabutyl, tetraoctyl, tetrakis (hexadecyl), tributyl (tetradecyl), tributyl (hexadecyl) and trioctyl (methyl) -ammonium or -phosphonium.

It is also possible in principle to use phenyl (alkyl) derivatives, although due to their poorer solubility compared to representatives exclusively aliphatically substituted in solvents or solvation media suitable for use in the oligomerization of isocyanates, especially monofunctional alcohols, they are less preferred.

In general, the special role, the type and amount of the solvation agent (s) S present during the catalysis for the preferred formation of iminooxadiazinedione groups is not foreseeable for the person skilled in the art.

The molar ratio F ": S is, however, significantly decisive for carrying out the process according to the invention in order to achieve a high content of iminooxadiazinedione groups, that is to say at least 30f in moles in the mixture of trimers.

The present invention differs significantly from previous publications which describe or reproduce the use of fluorides for the trimepzation of isocyanates with formation of isocyanurates by the surprising observation that the selectivity of the catalysis depends significantly on the concentration of the catalyst.

Thus, in DE-A 38 27 596 reference is made to the possibility of manufacturing polyisocyanates having isocyanurate groups with ammonium fluorides and quaternary phosphonium. In the indicated patent publication it is explicitly highlighted on p. 3, lines 30-35 that the fluoride concentration of the solution used for the homogeneous catalysis should not exceed 0.5 mMol of F "per g of solution, using as solvent for example 2-ethyl-l, 3-hexanediol, acetonitrile or N, N-dimethylformamide (DMF).

Own tests, carried out according to the method proposed in DE-A 38 27 596, show, however, that the use of these fluorides dissolved in the indicated solvents, at the concentration of fluoride ions preferred mentioned in the aforementioned applications (0.01 -0.1 mMol of F "per g of solution, ie approximately 0.02-0.2% of F" in the catalyst solution), leads only to the formation of extremely turbid products that are totally mutilizable as high-quality isocyanate components, for example for the manufacture of lacquers and polyurethane coating agents. The proportion of iminooxadiazindione in the mixture of product trimer thus manufactured is also small and is greatly reduced by diluting the catalyst solution strongly with the aforementioned solvents (Example 2, Table 1).

The aprotic solvents of the catalyst such as acetonitrile or DMF are generally unsuitable for the intended processThese, therefore, in the recovery, for example by distillation, of unreacted monomers, for example of dusocyanates such as HDI, which are usually carried out following the (partial) trimerization of the isocyanate groups, are eliminated with these of the process and then used again, again together with these, so that with the successive repetition of this process would be enriched more and more what would make it necessary sooner or later its costly separation of the monomer "cyclically driven". A similar procedure would naturally be affected by serious shortcomings from, among other, economic points of view.

Furthermore, DMF can react with isocyanates at elevated temperature, forming undesired byproducts (see Angew Makromol, Chem., 1992, 197, 131-139, release of CO2 and formation of formamidine) and in combination with basic substances (for example impurities). at lower temperature they catalyze the undesired linear polymerization of the (poly) isocyanates forming extremely insoluble 1-nylon compounds (for example "Organic Chemistry, A Series of Monographs, "volume 13 B / 2, Acad. Press, New York and London, pp. 332 ff., And bibliography therein).

To this is added that by using aprotic catalyst solvents such as acetonitrile and DMF, also using relatively highly diluted catalyst solutions, gross turbid trimerized solutions are formed which contain very thick gel-like solid matter particles which can only be further used in the process after costly filtration steps and even then they do not provide fully turbidity-free resins after processing by molecular distillation (see Examples 2b and 2c). The proportion of iminooxadiazinedione in the trimerized product resins thus manufactured is also very small (Table 1).

Furthermore, in the exemplary embodiments of DE-A 38 27 596 there is only a reference to the preparation of a phosphonium fluoride catalyst which was also applied on a solid support (silica gel) (page 6, Tab.1, Example 4) . Its use for the modification of isocyanates is not mentioned in the mentioned patent publication.

Similar catalyst systems, here in conjunction with CO 2, and their use for the manufacture of modified polyisocyanates having isocyanurate groups are described in DE-A 39 62 078, although the phosphonium salts are expressly disclosed in various places in this publication of patent as "less preferred" in relation to ammonium species (page 3, lines 32/33, lines 60/61, page 4, line 12). The references to the preferred catalyst concentrations in the homogeneous catalysis are analogous to those already found in DE-A 38 27 596. In the examples of embodiment of the above-mentioned patent publication there is no further reference to the preparation or use of phosphonium fluorides as a catalyst for the modification of isocyanates. It is also expressly emphasized in the aforementioned patent publication that in the resulting products "the proportion of iminooxadiazinedione is maintained at a lower order magnitude" (page 4, lines 51-52). Exemplary embodiments 6 to 9 in DE-A 39 02 078, which report the partial formation of iminooxadiazinediones together with isocyanurate and oxadiazinetrione as the two main products of the reaction, suggest in the end that on the one hand, the formation of iminooxadiazinedione requires the presence of C02 in the trimerization reaction and that, on the other hand, the iminooxadiazinediones are more likely to be undesired byproducts.

Both DE-A 38 27 596 and DE-A 39 02 078 give an allusion to the special role played by the catalyst solvent, not only for the dilution of the catalyst, but also to guarantee a course of the reaction without problems, that is, to avoid formation of turbidity or solids, as well as a selectivity control agent (solvating agent) for the preferred formation of iminooxadiazinedione groups in the trimerization of the isocyanates.

It is also found in the literature (patents) - references on the possibility of a use of phosphonium fluorides generated "in situ" from an alkaline or alkaline earth fluoride and another quaternary phosphonium salt (chloride, bromide, etc., see more above), for the modification of isocyanates (phase transfer catalysis, for example Isr. J Chem., 1985, 26, 222-224, however the use of phosphonium fluorides is not described here).

Following these ideas in the document EP-A O 315 692 are described processes catalyzed with potassium fluoride for the manufacture of substances with cyclic isocyanurate structures, which among other things proposes the simultaneous presence of onium compounds for the "increase in the efficiency of the reaction" In the examples of embodiment of this patent publication, however, there is no reference to the use of phosphonium salts. In addition, the trimerization of aromatic isocyanates (TDI, MDI) is basically dealt with and only the catalytic activity of the potassium fluoride itself (example 1 of EP-A O) demonstrates by the reaction of n-butyl isocyanate with KF in two examples. 315 692) or in the presence of the quaternary ammonium salt (benzyltrimethylammonium chloride, example 5 of EP-A 0 315 692) for the trimerization of isocyanates with NCO groups linked aliphatically with isocyanurate formation.

The method is not practical for use on a commercial scale due to the following disadvantages: 1) the high reaction temperature (120 ° C) as well as the comparatively long reaction times (8 h in Example 1, 4 h in Example 5 of EP-A 0 315 692) with high catalyst concentration, 2) the technically disadvantageous separation of the solid potassium salt components after the reaction by filtration (example 1 of EP-A 0 315 692) or washing with water (example 5 of EP-A 0 315 692), which prevents the separation of products containing isocyanate groups and 3) as well as the fact that with the claimed use of onium salt together with potassium fluoride a continuous "extraction" of fluoride ions is carried out from the more soluble inorganic phase, which is referred to as the catalyst itself, in the organic phase which contains isocyanate, make the method in general appear to be unprofitable and practically unfeasible technically.

In the reaction known from EP-A 235 388 of isocyanates with carboxylic acids or their anhydrides catalyzed by fluorides, the corresponding polyamides / imides are obtained, but no NCO / NCO reaction product.

In none of the aforementioned publications is any reference made to the (co) formation of iminooxadiazinedione structures together with the described isocyanurates.

Therefore, it was not foreseeable for the specialist on the basis of the state of the art described above that in organic media (as a rule the isocyanate (or mixture of) to be modified) could be particularly advantageous for the preparation of trimerized resins. of isocyanates lacking turbidity with a high proportion of iminooxadiazinedione groups in the mixture of fully soluble trimers, ammonium fluorides or quaternary phosphonium, or special combinations of these phosphonium fluorides with certain solvation agents for the fluoride anion of the type described in more detail in the present invention.

According to the process according to the invention, protic solvating agents S can be used as water, alcohols and / or aliphatic and aromatic carboxylic acids, as discussed in more detail below. However, the amount of the respective S to be added in order to achieve the highest content of iminooxadiazindiones is limited upwards, that is, by successively reducing the concentration of ammonium fluoride or quaternary phosphonium in the catalyst mixture, this loses its shape. increasing its selectivity for the formation of the iminooxadiazinedione preferred and forming, in addition to the by-products resulting from the presence of S, essentially only the isocyanurates known for some time.

Suitable monoalcohols are straight-chain or branched, primary, secondary and tertiary alcohols with up to twenty C atoms, preferably from one to eight C atoms, for example methanol, ethanol, n- as well as iso-propanol, 1- and 2- butanol, isobutanol and 2-ethylhexanol.

Oxalic acid and weaker acids which have a pKa value greater than 2, such as for example formic acid, acetic acid, pivalic acid (s) (optionally substituted with hydroxy groups), are generally suitable organic acids. ), malonic acid, succinic acid as well as propan-1,3-dicarboxylic acid (optionally substituted in the CH group (s)), as well as phthalic acid, salicylic acid, etc. As a tabulation condition for the pKa value, water at 25 ° C is generally indicated (see also example 5).

The process according to the invention can be carried out in a temperature range from about 20 C (room temperature) to about 200 C, preferably between 30 ° C and 120T, particularly preferably between 40 ° C and 100 ° C, with partial transformation of the isocyanate groups involved in the poly (isocyanate (s) / mixture, starting at the reaction degree RNco / calculated as the ratio of the NCO content difference of the poly (isocyanate (s) / mixture) of, starting, before the trimerization and the NCO content of the reaction mixture after the reaction has been stopped and the NCO content of the poly (isocyanate (s) / mixture of, starting before the trimerization, between 5% and 60%, preferably between 10% and 40%.

Here, the unreacted monomer can be separated after deactivation of the catalyst system, for example by (molecular) distillation or extraction, and then reused.

For the deactivation of the catalyst system after obtaining the desired R.NC.sub.o, all previously described prior art methods, such as those used to stop the trimerization reaction in which isocyanurates are formed, are suitable in principle. These are, for example, the addition in sub- or also supra-stoichiometric amounts of strong acid or acid derivatives (for example benzoyl chloride, acid esters of phosphorous acid and phosphoric acid, these acids themselves, etc., but not the HF and other weak acids with a pKa value less than 2.0), fixing the catalyst by adsorption and subsequent separation by filtration, thermal deactivation, etc.

The elimination of excess starting isocyanate (s), as long as these (these) are (n) (a) (di) isocyanate Cs) "monomer (s)" of low molecular weight, is preferably carried out if the products of the process according to the invention are intended for applications in the sector of polyurethane lacquers and coating agents. In this respect, the excellent chromatic index and stability of the process products as well as their high stability against retrodissociation in the base monomer (s) (di) isocyanate (s) are used.

For the production of the trimers (mixtures of) according to the invention, concentrations of catalyst, based on the (poly) isocyanate (mixture of) used and the fluoride ion (molar mass 19), between 1 ppm and 1, preferably between 1 ppm and 0.1%, with particular preference between 1 ppm and 0.05 ?.

According to a special embodiment, which works continuously, of the process according to the invention, the oligoing is carried out in a tubular reactor.

Here, the least tendency, in particular of the phosphonium fluoride catalysts, is used, although they are applied in highly concentrated solution or as pure active substance, to spontaneously form gel particles in the product. In addition, highly concentrated catalyst solutions can be used, as in the case of discontinuous trimerizations ("batches" trimerizations), since the mixing speeds in tubular reactors with turbulent piston flow with respect to the mixture of the reactants in agitation reactors are notably accelerated, the mechanism of slow release, by its abbreviations in English "slow reléase" mentioned above must consequently extend significantly less time.

The process according to the invention can be carried out both without solvent and also by diluting the starting (poly) isocyanate or the (poly) isocyanates (mixture of) starting. For the dilution, all organic compounds which are inert towards NCO groups, such as toluene, xylene (s), higher aromatics, esters, ethers, ketones, alkylsulfonic esters C: .- C, are suitable here. as well as mixtures of such solvents.

For carrying out the process according to the invention, all di or polyisocyanates having a molecular weight (average) of 140-600 g / mol with isocyanate groups linked aliphatically, cycloaliphatically and / or araliphatically, independent of each other, in pure form or as discretionary mixtures with each other. As an example they are to mention: Hexamethylene diisocyanate (HDI), 2-methylpentan-1,5-diisocyanate (MPDI), 1,3-bis (isocyanatomethyl) cyclohexane (1,3-H6-XDI, 3 (4) -isocyanatomethyl-1-methyl-cyclohexyl isocyanate (IMCI) ), isophorone diisocyanate (IPDI), bis (isocyanatomethyl) -norbornane (NBDI), 4-isocyanatomethyl-l, 8-octane diisocyanate (triisocyanatononane, TIN), 1,3-bis (isocyanatomethyl) benzene, 1,3-bis (2-isocyanatopropyl-2) benzene and bis (4 (2) -isocyanatocyclohexyl) methane (H-MDI, Desmodur "W, product from Bayer AG) Here, the process by which the above-mentioned (poly) isocyanates are manufactured, ie with or without the use of phosgene, is of no importance.

Preferably HDI, MPDI, 1,3-H6XDI, NBDI as well as mixtures of HDI and IPDI are used.

It can also be advantageous to use mixtures of certain (poly) isocyanates in the process according to the invention, for example to optimally match the requirements profile of the respective product or mixture of products. Thus, in many applications, for example in the (factory) automotive paint, mixtures of linear aliphatic base, for example branched, for example HDI, and, on the other hand, cycloaliphatic dusocyanates, for example IPDI, are used. or H? 2MDI (DesmodurR W, commercial product of Bayer AG). These mixtures are prepared as a rule by further mixing of polyisocyanates based on diisocyanates of one type with those of the other. However, it can also be advantageous to prepare them by simultaneous mixed addition from the corresponding mixture of the monomer components (EP-A 00 47 452). Many polyphocyanates based on cycloaliphatic diisocyanates of the state of the art are solid. They sometimes have such a high melt viscosity that the separation of monomers by (molecular) distillation sometimes causes considerable difficulties. Therefore, it is necessary to use solvents or creep aids for their processing or sometimes also in molecular distillation. If you do not want to suffer too great losses in the degree of transformation (yield in ream) and NCO functionalization in the manufacture of these polnsocyanates the concentrations of the solution are 70% resin (solid), for example in polyisocyanates with isocyanurate, based on cycloaliphatic diisocyanates, with good processable dynamic viscosities between one and ten Pa.s (measures at 23 ° C) commercial of the state of the art.

If, on the other hand, mixtures of linear aliphatic diisocyanates, for example HDI, and cycloaliphatics, for example IPDI, are trimerized, according to the process according to the invention with (partial) formation of iminooxadiazinedione, flowable products are also obtained at room temperature (viscosity at 23 ° C). C less than 100 Pa.s) which also have a drastically faster reduction in viscosity by successive additions of solvent, as composition products (NCO functionalization, diisocyanate base, average molecular weight) corresponding to the state of the art (Example 6) .

The products or product mixtures obtainable according to the process according to the invention therefore represent polyvalent starting materials for the production of plastic (s), if applicable expanded, as well as lacquers, coating agents, glues and additives.

Before use as an isocyanate component in polyurethane systems, the process products are additionally modified, if appropriate, in the isocyanate groups, for example by introducing urethane, urea, biuret and / or allophanate groups or partially or completely transforming the NCO groups with special compounds, that can be eliminated again ("blockers"). For example, phenols, lactams, such as e-caprolactam, oximes, di and triazoles, certain amines, such as diisopropylamine, compounds with acidic CH such as, for example, dialkyl esters of malonic acid, ethyl acetoacetate, etc. are suitable.

Especially for the production of one and two-component polyurethane lacquers, optionally dispersible in water, they are suitable, if necessary in the form NCO blocked, due to its low viscosity in solution as well as in the molten state compared to products based (predominantly) on polyisocyanates with isocyanurate groups with, in addition, an equally high or improved property profile. Thus, the products of the process according to the invention based on HDI are, also at high dilution in lacquer solvents, more stable against the appearance of flocculations or turbidity than the corresponding products containing, basically, isocyanurate groups of the state of the art. Its resistance to the action of moisture (for example, formation of outdoor scale, matt appearance of the surfaces that are lacquered with higher humidity and room temperature, called ("reduction of brightness", for its acronym in English "do nglossing") is also improved in relation to the products that contain (almost) exclusively isocyanurate groups.

The invention will be further illustrated, but is not intended to be limited by the following examples in which all parts and percentages are by weight, unless otherwise specified.

Examples All percentage data are, unless otherwise indicated, in percentages by weight.

The data from ? in moles were determined spectroscopically and are always referred, unless otherwise indicated, to the sum of the NCO derivative products that are formed by the modification reaction ("trimerization"). The measurements are performed on a DPX 400 apparatus from the Brucker firm in samples at approximately 5% (XH NMR) or approximately 50% (13 C NMR) on anhydrous CDC13 at a frequency of 400 MHz (XH NMR) or 100 MHz (1 C NMR). As a reference for the ppm scale, small amounts of tetramethylsilane are chosen in solvents with a chemical shift of l of 0 ppm (NMR of: H) or the solvent itself (CDCl 3) with a displacement of 77.0 ppm (RMN of ljC). The data for the chemical displacement of the compounds in question are taken from the literature (see Die Ange andte Makromolekulare Chemie 141, 1986, 173-183 and the literature cited therein) or by measurement of model substances. 3, 5-Dimethyl-2-methylimino-4,6-diketo-1,3,5-oxadiazine obtainable according to the procedure described in Ber. d. dtsch. Chem. Ges. 1927, 20, 295 from methyl isocyanide with catalysis with 3 * of tri-n-butylphosphine with a yield of approximately 70% shows the following chemical shifts in NMR (in ppm): 3.09, 3.08 and 2.84 (NMR of: H , CH.) And 148.3, 144.6 and 137.3 (NMR of * 'C, C = 0 / C = N). The products of the process according to the invention with the iminooxadiazinedione structure have very similar changes or chemical shifts in 1 JC NMR of the C = 0 / C = N atoms and can undoubtedly be differentiated as such from other isocyanate-derived products.

The dynamic viscosities were determined at 23 ° C with a VT 550 viscometer from Haake. By measuring at different cutting speeds it has been established with certainty that the flow behavior of the polyisocyanate mixtures according to the invention as well as that of the comparison products corresponds to that of ideal neonatal fluids. Therefore, data on cutting speeds can be suppressed.

The determination of the residual content of monomers was determined by gas chromatography.

The turbidity of the trimerized resins was determined with an apparatus of the firm Hach. For this, measurements of light dispersed at 90 ° with respect to the direction of a light beam of the wavelength of 400-800 nm conducted through the resin sample were made and are given in units referring to formazin standard solutions, UT (F).

The majority of the reactions were carried out by way of example with HDI as isocyanate to be trimerized and with catalysts based on tetrabutylphosphonium fluoride under a nitrogen atmosphere. This was done only to clarify the advantages of the process according to the invention and does not mean any limitation of the present invention to the described reaction systems or conditions.

Example 1: Preparation of quaternary ammonium fluorides (stock solutions) According to J. Or-g. Chern. 1989, 54, pgs. 4827-4829. (The preparations for R ^ N + C1"were carried out analogously to those of R4P * C1 ~) a) Bu4P * F "in methanol / iso-propanol (stock solution). 953.8 g of a Bu4P * solution was dissolved Cl "at 71.4% in iso-propanol (CyphosR 443P, product of the Cytec firm), corresponding to 2.3 mol of Bu4P * Cl" in 1 kg of technical methanol (approximately 0.2% H20), was mixed with 150 g (2.58 mol) of pulverized potassium fluoride and stirred for 24 h at 20-25 ° C (room temperature). Then it was filtered, the filter residue was washed twice with 100 g of technical methanol. and the combined filtrates were again mixed with 150 g (2.58 mol) of pulverized potassium fluoride and stirred for 24 h at 20-25 ° C (room temperature). After subsequent filtration and new two washes with 100 g of methanol tecn. each one, methanol and iso-propanol in excess were largely removed at 30 ° C maximum and a pressure of about 1 mbar in a rotary evaporator and filtered again.The solution thus obtained practically colorless presented the following data: Fluoride (with ion selective electrode at pH 5.5): 5 * Chlorine (total, by digestion, gravimetrically): 0.4% MeOH (by gas chromatography, according to normalization): 16.3% i-PrOH (by gas chromatography, according to standardization ): 7.3% b) Bu. (C; 4H ..) P * F "in methanol / iso-propanol (stock Ib) 500 g of a solution of Bu, (C -., H ..) P 'Cl "to 7 .2'. In iso-propanol (Cyphos 3453P, product of the firm Cytec), corresponding to 0.85 mol of Bu, (C: 4H;,) P 'Cl "in 0.5 kg of technical methanol (approximately 0.2 * of H ^ 0), was mixed with 50 g (0.86 mol) of pulverized potassium fluoride and stirred for 24 h. -25 ° C (room temperature), then filtered, the filter residue was washed 2 times with 50 g of technical methanol, the combined filtrates were again mixed with 50 g (0.86 mol) of pulverized potassium fluoride and stirred for 24 h at 20-25 'C (room temperature) After subsequent filtration and two further washes with 50 g of methanol technically, methanol and iso-propanol in excess at 30 ° C at most and pressure of about 1 mbar in a rotary evaporator and filtered again The solution thus obtained presented the following data: Fluoride (with ion selective electrode at pH 5.5): 3.65% Chlorine (total, by digestion, gravimetrically): 0.145% MeOH (by gas chromatography, according to standardization): 9.1% i-PrOH (by gas chromatography, according to standardization) 3.8% c) Phj (Bu) P "F" in methanol (mother solution) g (56.3 mmol) of Ph3 (Bu) P + Cl were dissolved " (signature Chemconserve) in 40 g of methanol tecn. (about 0.2% H.0), 3.3 g (56.8 mmol) of powdered potassium fluoride was added and stirred for 24 h at 20-25 C (room temperature). After it was filtered, the filter residue was washed twice with 5 g of technical methanol. and the combined filtrates were again mixed with 3.3 g (56.8 mmol) of pulverized potassium fluoride and stirred for 24 h at 20-25 ° C (room temperature). After subsequent filtration and two new washes with 5 g of methanol tecn. each one removed the excess methanol at 30 ° C maximum and a pressure of about 1 mbar on a rotary evaporator until the crystallization started and filtered again. Here you must take care that only potassium salts are separated, that as a result of a subsequent concentration precipitate in the solution, and that no phosphonium salt remains in the filter residue (solubility test). The solution thus obtained presented the following data: Fluoride (with ion selective electrode at pH 5.5): 3. 15% Chlorine (total, by digestion, gravimetrically): < 0.2% MeOH (by gas chromatography, according to normalization): 42.8% d) R, (Me) N * F "in methanol / iso-propanol (stock solution Id) 151 were dissolved. 3 g of a solution of R. (Me) N 'Cl "to approximately 90% in iso-propanol' Adogen 464, product of the Aldrich form, R represents Cs-? Residues or predominantly those of Cs, chlorine content: 7.1%) in 170 g of Technical methanol (approximately 0.2% H20) was mixed with 17.6 g of pulverized potassium fluoride and stirred for 24 h at 20-25 ° C (room temperature), then filtered, the filter residue was washed twice with 100 g. g of technical methanol and the combined filtrates were again mixed with 17.6 g of powdered potassium fluoride and stirred for 24 h at 20-25 ° C (room temperature), after subsequent filtration and two further washes with 100 g of methanol technology each. one of the excess methanol and iso-propanol was removed at a maximum of 25 ° C and a pressure of about 1 mbar on a rotary evaporator to constant weight and filtered again.The weakly colored solution of yellow showed the following data: Fluoride (with ion selective electrode at pH 5.5): 3.4% Chlorine (total, by digestion, gravimetrically): 0.2% MeOH by gas chromatography, according to standardization): 13.9% i-PrOH (by gas chromatography, according to standardization): 2.5% Example 2: Comparative example a) Trimerization of HDI with a solution of tetrabutylphosphonium fluoride to approximately 1.5% in 2-ethyl-l, 3-hexanediol (approximately 0.1% F ", preferred region of the catalyst concentration according to DE-A 38 27 596 or DE-A 39 02 078).

In a three-neck flask with agitator firstly removed at 60 ° C by stirring for about one hour under vacuum (0.1 mbar) the dissolved gases of 200 g (1.19 mol) of HDI, was aerated with nitrogen and then carried away The trimerization reaction was carried out over the course of 4 h by adding dropwise a solution diluted with 2-ethyl-l, 3-hexanediol to approximately 0.1% F "of the stock solution of Bu4P + F" up to an NCO content. of the crude solution of 42.1% (catalyst consumption: 46 ppm of F), interruption with 103 g of dibutyl phosphate.) In the course of the addition of catalyst, solid matter particles are gradually formed and deposited through the catalyst. of the liquid especially in the walls of the flask The resin obtained after filtering the crude solution through a pleated filter and subsequent molecular distillation in a laboratory evaporator, evaporator of the short path type, to 140 ° C / 0.2 mbar presented the data shown in Table 1.

If, for example, glycol is used instead of 2-ethyl-1, 3-hexanediol as a solvent for the catalyst, analogous effects are in principle produced: too high turbidity of the crude solutions of the trimerization and of the resins with a tendency to a degree of formation of iminooxadiazindione the lower the more the catalyst is diluted. b) Trimerization of HDI with a solution of tetrabutylphosphonium fluoride to about 1.5% in acetonitrile (approximately 0.1 of F ", preferred region of catalyst concentration according to DE-A 38 27 596 or DE-A 39 02 078) . c) Trimerization of HDI with a solution of tetrabutylphosphonium fluoride to approximately 1.5% in DMF (approximately 0.1% F), preferred region of catalyst concentration according to DE-A 38 27 596 or DE-A 39 02 078 ).

The procedure was completely analogous to that in Example 2a. In this way, crude turbid solutions were obtained containing approximately 3% aprotic solvent, which after expensive filtration (gel-like solid particles) and molecular distillation gave strongly clouded resins (Table 1). The process was, due to the complex separation of the solvent from the catalyst very laborious in any case and therefore barely realizable.

See also the exposures found in Example 4 for the dosing of the catalyst by other dosing techniques ("injection") Table 1 Comparative example for catalysis with quaternary phosphonium fluoride (not according to the invention).

Example 3: Use of water as solvating agent S The mother liquor la, b, c or d respectively was mixed with one equivalent of water, based on the fluoride content, and the mixtures were used for the HDI mixtures in the manner described in 2a. Here again the monomer recovered in the respective previous test was added again (runs 3-1 to 3-3, respectively a-d) to complete the amount of HDI removed as resin in the previous test. In these tests, formation of flocs or solids was not observed during the reaction, the isolated reams showed a very low turbidity level and a high content of imoxadiazinedione (see Table 2). The UfJCo was at approximately 20 *. The interruption of the prolongation of the reaction was performed by adding the molar amount of dibutyl phosphate corresponding to the consumption of F ". The consumption of F" of the reaction reached between 10 and 30 ppm, based on the weight of HDI used and the relative weight of the fluoride ion, 19 g / mol.

If the amount of H20 in the used catalyst is raised to 5 or 10 equivalents per equivalent of F "in the stock solution (tests 3-4 and 3-5), the proportion of iminooxadiazinedione in the trimerization mixture is successively reduced. Also in assay 3-5, highly viscous HDI derivatives resulting from the NCO-H_0 reaction (basically biuret and oxadiazintrione, the latter formed by immediate incorporation catalyzed by carbon dioxide fluoride) can be detected well in resin by NMR spectroscopy. which is released in the NCO-H: 0 reaction, see also DE-A 39 02 078).

Table 2 Results of HDI trimerization catalyzed by phosphonium fluoride or ammonium using water as solvating agent S for the fluoride ion Example 4: Use of alcohols as solvating agent S All Examples relating to the manufacture of products containing less than 30% by mole of iminooxadiazinedione in the mixture of trimers and / or surpassing a turbidity value of 1.5 UT (F) are comparative examples.

The stock solution was used as such (Test 4-0) or more diluted with the alcohols set forth in Table 3 at the concentration respectively set forth in Table 3, for the trimerization of HDI as described in 2a (respective RNCo approximately 20). %, interruption by addition of the molar amount of dibutyl phosphate corresponding to the consumption of F ", consumption of F" of the reaction 20-50 ppm of F ", based on the weight of HDI used and the weight of the fluoride ion, 19 g / mol).

Only if the catalyst is used at a very high concentration (Test 4-0) can small formations of solids occasionally be observed in the reaction solution In these cases the crude product can either be filtered before processing by molecular distillation, which is achieved practically without problems as in the cases shown in 2b and 2c, or else inject the catalyst to achieve a more homogeneous mixture faster. If this is done with the catalyst solutions used in 2b and 2c the nozzles are immediately clogged with solid matter.

The content of iminooxadiazinedione, on the other hand, is then at the high level according to the invention if the amount of alcohol (molar) does not substantially exceed about 20 times the concentration of the fluoride ion, ie the concentration of the catalyst should not exceed approximately 20. to 30% (see Table 3).

Table 3 Results of the trimerization of HDI catalysed with phosphonium fluoride using monofunctional alcohols as solvation agent S for the fluoride ion.

Injecting the catalyst, see text Example 5: Use of organic acids as solvating agent S In the stock solution equimolecularly, relative to the relative weight of the fluoride ion, 19 g / mol, the respective organic acid set forth in Table 4 was dissolved and the resulting mixtures were used for the transfer of HDI in the manner described in 2a (respective UNCo). of about 20 *, interruption by addition of the molar amount of dibutyl phosphate corresponding to the consumption of F ", consumption of F" of the reaction 20-50 ppm of F ", referred to the weight of HDI used and the relative weight of the ion fluoride, 19 g / mol) No reaction was observed during the reaction, regardless of the type of catalyst addition, solid matter formation The contents of iminooxadiazinedione are shown in Table 4.

Table 4 Results of the trimerization of HDI catalyzed with phosphonium fluoride using organic acids as solvating agent S for the fluoride ion * pKai is always indicated in polybasic acids; intervals are indicated if the data differ somewhat from those in the literature (Handbook of Chemistry and Physics, 67th edition, 1986-1987 CRC Press, Boca Raton, Florida, pgs. D-163 and next. or Beilstein, online data bank).

Example 6: Mixed trimerization of HDI / IPDI A mixture of 100 g (0.59 mol) of HDI and 100 g (0.45 mol) of isophorone diisocyanate (IPDI) in a 250 ml four-necked flask with internal thermometer, stirrer, reflux condenser, gas introduction tube and dosing device was first subjected to room temperature and a pressure of about 0.1 mbar in the course of one hour to removal of gases from the diisocyanate mixture and then heated to 60 ° C while introducing a weak stream of nitrogen. Subsequently, a total of 0.3 g (75 ppm F) of the stock solution was added dropwise at that temperature over the course of about 20 minutes and trimerized at 60-70 C to an NCO content of the mixture of 34.0% was interrupted by adding 0.2 g of di-n-butyl phosphate, stirring was continued for another hour at 60 ° C and then the monomeric diisocyanates that had not reacted by molecular distillation were separated in a short path evaporator at 0.1 mbar and a heating medium temperature of 170 ° C. The transparent resin (turbidity = 1.1 UT (F)) and practically colorless (65.6 g corresponding to a yield of 32.8%) presented in pure form a viscosity of 23,000 mPa. s, an NCO content of 20.3% and a residual monomer content of 0.07% HDI and 0.18% IPDI.The content of iminooxadiazinedione in the mixture of trimers amounted to 41.5%.

Example 7: First of all 100 g (0.51 mol) of 1,3-bis (isocyanatomethyl) cyclohexane (Aldrich) were treated first as described in Example 6 and then trimerized by adding portions of the polyfluoride solution in portions in the course from 3 hours to an NCO content of 36.6%, succinctly catalyst consumption: 42 ppm of F "at 58-60 ° C. Then it was stopped by adding 100 mg of di-n-octyl phosphate, stirring was continued for another hour to 60 C and the 1, 3-bis (isocyanatomethyl) cyclohexane which had not reacted by molecular distillation was removed in a short path evaporator at 0.2 mbar and a heating medium temperature of 140 ° C. The transparent and practically colorless resin (33.5 g corresponding to a yield of 33.5%) presented an NCO content of 19.9% and in pure form at room temperature (20-25 ° C) it is still fluent. The viscosity of the 80% solution in n-butyl acetate was 1530 mPa.s, with an NCO content of 15.9%. The residual monomer content amounted to 0.07% of 1,3-bis (isocyanatomethyl) -cyclohexane. The proportion of iminooxadiazinedione in the mixture of trimers amounted to 45.2%.

Although the invention has been described in detail in the above items for purposes of illustration, it can be understood that such detail is only for those purposes and that variations can be made here by those skilled in the art without departing from the spirit and scope of the invention. the invention, except as may be limited by the claims.

It is noted that in relation to this date, the best method known to the applicant, to put into practice the aforementioned invention is that which is clear from the manufacture of the objects to which it refers.

Having described the invention as above, the content in the following is declared as property.

Claims (4)

1. Process for the production of polyisocyanates with at least 30% by weight of iminooxadiazinedione groups (asymmetric trimers), based on the total amount of isocyanurate and iminooxadiazinedione groups, by catalytically induced trimerization of organic di- or polyisocyanates with a molecular weight (average) of 140-600 g / mol with isocyanate groups linked aliphatically, cycloaliphatically and / or araliphatically, independent of each other, characterized in that ammonium fluorides or quaternary phosphonium of formula are used as trimerization catalyst. R4E * F " where E represents N or P and R represents aliphatic radicals, optionally branched, aromatic and / or araliphatic, identical or different, and it is also possible for two or more R substituents to form with each other and with the nitrogen or phosphorus atom saturated or unsaturated cycles, in which the catalyst is i) present in the pure form ii) mixed with solvating agents S for the fluoride anion, where S can be a pure compound or a mixture of different substances from the group of protic compounds with a pK value greater than 2 (determined in H, 0 to 25 ° C) as well as oxalic acid, but no alcohol of superior functionalization (di- or polyol) nor HF, with the proviso that the molar ratio of 6 to fluoride ion (F ") does not exceed the value of 20. iii) mixed with water, where the molar ratio of water to fluoride ions (F ") does not exceed 10.

2. Process according to claim 1, characterized in that aliphatic diisocyanates of a molecular weight (range) of 140-300 g / mol are used as pure compounds or mixed discretionally with each other and because the products of the process contain at least one of the isocyanate components to be trimerised. 3 moles of iminooxadiazinedione groups (asymmetric trimers), based on the total amount of isocyanurate and iminooxadiazinedione groups.

3. Process according to claim 1, characterized in that as trimer catalyst 7a ion are present at a concentration of 20% by weight in one or more alcohols having a numerical average molecular weight of 32-250.

4. Process according to claim 1, characterized in that the trimerization catalyst is mixed with a solvating agent S and the molar ratio of the organic acid to fluoride ions F ", does not exceed the value of 10. SUMMARY OF THE INVENTION The invention relates to a process for the preparation of polyisocyanates with at least 30 mol% of iminooxadiazinedione groups (asymmetric trimers), based on the total amount of isocyanurate and iminooxadiazinedione groups, by catalytically induced trimerization of organic di- or polyisocyanates with a molecular weight (medium) of 140-600 g / mol with isocyanate groups linked aliphatically, cycloaliphatically and / or araliphatically, independent of each other, characterized in that ammonium or quaternary phosphonium fluorides of the formula are used as trimerization catalyst R4E * F "(I), where E represents N or P and R represents aliphatic radicals, optionally branched, aromatic and / or araliphatic, identical or different, and it is also possible for two or more R substituents to form with each other and with the nitrogen or phosphorus atom saturated or unsaturated cycles, in which the catalyst is i) present in the pure form ii) mixed with solvating agents S for the fluoride anion, where S can be a pure compound or a mixture of different substances from the group of protic compounds with a pKa value greater than 2 (determined in H: 0 to 25lC) as well as acid oxalic, but no higher functionalizing alcohol (di- or polyol) or HF, with the proviso that the molar ratio of S to fluoride ion (F ~) does not exceed the value of 20. iii) mixed with water, where the molar ratio of water to fluoride ions (F ") does not exceed 10.