Process for isocyanate modification using a spirocyclic ammonium salt as catalyst

Abstract

The invention relates to a process for producing a modified isocyanate, comprising the reaction of a monomeric isocyanate in the presence of a catalyst to form a reaction mixture, wherein the catalyst comprises at least one spirocyclic ammonium salt containing at least one spirocyclic ammonium cation and at least one anion. The invention further relates to a modified isocyanate obtainable by the process according to the invention and the use thereof for producing polyurethane bodies or coatings, as well as to the polyurethane bodies or coatings. The invention further relates to one-component or two-component systems comprising the polyisocyanates having improved properties.

Description

[0001] Method for isocyanate modification using a spirocyclic

[0002] Ammonium salt as a catalyst

[0003] The invention relates to a process for producing a modified isocyanate comprising the reaction of a monomeric isocyanate in the presence of a catalyst to form a reaction mixture, wherein the catalyst comprises at least one spirocyclic ammonium salt containing at least one spirocyclic ammonium cation and at least one anion. The invention further relates to a modified isocyanate obtainable by the process according to the invention and its use for the production of polyurethane bodies or coatings, as well as the polyurethane bodies or coatings. The invention further relates to one- or two-component systems comprising the polyisocyanates with improved properties.

[0004] The oligo- or polymerization of isocyanates, particularly to form higher molecular weight oligomer mixtures with uretdione ("dimer"), isocyanurate ("trimer"), and / or iminooxadiazindeione structures ("asymmetric trimer") in the molecular framework, has been known for a long time. As can be seen above, the oligo- or polymerization of isocyanates is based on essentially the same chemical reactions. The reaction of a small number of isocyanates with one another is called oligomerization. The reaction of a larger number of isocyanates is called polymerization. Within the scope of the present invention, the oligomerization or polymerization of isocyanates described above is collectively referred to as isocyanate modification or modification of isocyanates.

[0005] If the modified polyisocyanates contain free NCO groups, which may also have been temporarily deactivated with blocking agents, they are exceptionally high-quality starting materials for the production of a wide variety of polyurethane plastics and coating materials.

[0006] Several technical processes for isocyanate modification have become established. These typically involve reacting the isocyanate to be modified, usually a diisocyanate, by adding catalysts. Once the desired degree of conversion of the isocyanate to be modified is reached, the catalysts are deactivated by suitable means, and the resulting polyisocyanate is usually separated from the unreacted monomer. A summary of these state-of-the-art processes can be found in H.J. Laas et al., J. Prakt. Chem. 1994, 336, 185 ff.

[0007] Ionic compounds have proven effective as modification catalysts because they can be used in very small quantities relative to the monomer to be converted and lead to the desired result extremely quickly, with the cations being particularly important with regard to the solubility of the respective salt in the isocyanate environment.

[0008] WO 2015 / 124504 Al and WO 2017 / 029266 Al describe very stable ammonium salts in which the charge-carrying nitrogen atom is part of a ring system. However, these compounds have the disadvantage of being poorly soluble in isocyanate-functional polyisocyanate resin and therefore potentially causing turbidity in the final process products.

[0009] The invention was based on the objective of providing an improved process for isocyanate modification in which commercially available compounds, or those readily synthesized from inexpensive starting materials, are used as catalysts. These catalysts exhibit high catalytic activity and selectivity, combined with good catalyst stability and low turbidity of the process products. In particular, the objective was to provide spirocyclic ammonium salts as catalysts for the production of modified isocyanates with improved solubility in aprotic media, such as monomeric isocyanates like HDI and IPDI and their oligomers ("polyisocyanates"), compared to the prior art spiro compounds.

[0010] According to the invention, the problem was solved by a process for the production of a modified isocyanate comprising a. the reaction of a monomeric isocyanate in the presence of a catalyst to form a reaction mixture (a), wherein the catalyst comprises at least one spirocyclic ammonium salt containing at least one spirocyclic ammonium cation and at least one anion, wherein the spirocyclic ammonium cation includes at least one charge-bearing nitrogen atom which is part of two different ring systems (I) and (II), wherein the different ring systems (I) and (II) each consist of C2-C20 alkylene chains, wherein the respective alkylene chains may optionally be interrupted by heteroatoms such as oxygen, nitrogen or sulfur in the alkylene chain, wherein at least one alkylene chain of the two different ring systems (I) and (II) comprises at least one, preferably at least two,particularly preferably two to four and very preferably two or three exocyclic substituents other than H, wherein the at least one, preferably the at least two, particularly preferably the two to four and very preferably the two or three substituents other than H is bonded via a carbon-carbon bond, preferably a carbon-carbon single bond, to at least one carbon atom, preferably at least two different carbon atoms, particularly preferably two to four different carbon atoms and very preferably two or three different carbon atoms of the C2-C20 alkylene chains of the ring system (I) and / or (II).

[0011] According to the invention, exocyclic substituents are substituents in the side chain or side chains of the ring systems (I) and / or (II).

[0012] Preferably, references to "comprehensive," "containing," etc., mean "essentially consisting of" and, most preferably, "consisting of." The further embodiments mentioned in the claims and in the description can be combined as desired, in particular also among the various subject matter of the invention, unless the context clearly indicates otherwise.

[0013] “At least one,” as used herein, refers to one or more, for example, two, three, four, five, six, seven, eight, nine, or more. In the context of constituents of the compounds described herein, this term refers not to the absolute quantity of molecules but to the type of constituent. “At least one cyclic ammonium salt,” for example, means that only one type of cyclic ammonium salt or several different types of cyclic ammonium salts may be present, without specifying the quantity of each compound.

[0014] Numerical values ​​given herein without decimal places refer to the full value given with one decimal place. For example, "99%" means "99.0%".

[0015] Numeric ranges specified in the format "from x to y" include the stated values. If multiple preferred numeric ranges are specified in this format, it is understood that all ranges resulting from the combination of the different endpoints are also included.

[0016] In one embodiment of the invention, the spirocyclic ammonium salt contains exactly one spirocyclic ammonium cation and exactly one anion.

[0017] In one embodiment of the invention, the respective alkylene chains contain only carbon and hydrogen, i.e., the respective alkylene chains are not interrupted by heteroatoms such as oxygen, nitrogen or sulfur, especially oxygen, in the alkylene chain.

[0018] In one embodiment of the invention, the at least one substituent other than H is a branched or unbranched alkyl group, a branched or unbranched cycloalkyl group and / or a substituted or unsubstituted aryl group, preferably a branched or unbranched alkyl group.

[0019] In one embodiment of the invention, the at least one substituent other than H is a branched or unbranched alkyl group, wherein in a preferred embodiment the branched or unbranched alkyl group contains 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms. In an alternative embodiment of the invention, the respective alkylene chains are interrupted by heteroatoms such as oxygen, nitrogen, or sulfur, preferably oxygen, wherein, according to the invention, "interrupted" means, for example, the replacement of a CHi group of the alkylene chain by oxygen, formally resulting in an ether unit.

[0020] In one embodiment of the invention, the ring system (I) is composed of 3 to 5 atoms, preferably 4 to 5 atoms and particularly preferably 5 atoms, the spirocyclic ammonium cation being counted in each case.

[0021] In a preferred embodiment of the invention, the ring system (I) is composed of 3 to 5 atoms, preferably 4 to 5 atoms, and particularly preferably 5 atoms, and contains no exocyclic substituents other than H. In another embodiment of the invention, the ring system (II) is composed of 6 to 8 atoms, preferably 6 to 7 atoms, and particularly preferably 6 atoms, the spirocyclic ammonium cation being included in each count.

[0022] In a preferred embodiment of the invention, the ring system (II) contains at least one, preferably at least two, particularly preferably two to four and most preferably two or three exocyclic substituents other than H, wherein the at least two, preferably two to four and particularly preferably two or three substituents other than H in a side chain lead to a further increase in the solubility of the spirocyclic ammonium salts.

[0023] In a particularly preferred embodiment of the invention, the ring system (II) is composed of 6 to 8 atoms, preferably 6 to 7 atoms, and particularly preferably 6 atoms, and comprises two to four, preferably two or three, exocyclic substituents other than hydrogen, each with a branched or unbranched, preferably an unbranched, alkyl group, wherein the branched or unbranched alkyl group contains 1 to 10, preferably 2 to 6, carbon atoms. In one embodiment, the calculated molar mass of a branched or unbranched, preferably an unbranched, alkyl group is greater than that of at least one further branched or unbranched, preferably an unbranched, alkyl group.The molar mass of an alkyl group is calculated from the sum of the molar masses of the carbon and hydrogen in the respective alkyl group, where, for example, a molar mass of 15 g / mol results for a methyl group and a molar mass of 29 g / mol for an ethyl group.

[0024] In principle, all structural types known to be catalytically active towards isocyanates can be used as anions in the spirocyclic ammonium salt according to the invention; preferably, the hydroxide, alkanoate, carboxylate, heterocycles with at least one negatively charged nitrogen atom in the ring, in particular azolate, imidazolate, triazolate, tetrazolate, fluoride, hydrogen difluoride, higher polyfluorides or mixtures of these (adducts of more than one equivalent of HF to compounds containing fluoride ions), wherein the fluorides, hydrogen difluorides, dihydrogen trifluorides and higher polyfluorides lead to products with a high iminooxadiazinde ion group content according to the invention.

[0025] The spirocyclic ammonium salts used according to the invention can be used individually or in any mixture with each other. For example, solutions of quaternary ammonium hydroxides in various alcohols exist partially or completely as ammonium salts with an alkoxide anion, depending on the pKa value of the base and the alcohol used. This equilibrium can be shifted entirely towards complete alkoxide formation by removing the water of reaction resulting from this reaction.

[0026] In one embodiment of the invention, the anion is selected from the group consisting of hydroxide, alkanoate, carboxylate, heterocycles with at least one negatively charged nitrogen atom in the ring, fluoride, hydrogen difluoride, higher polyfluorides (i.e., adducts of more than one equivalent of HF to compounds containing fluoride ions) and any mixtures of the aforementioned, preferably hydrogen difluoride and / or dihydrogen trifluoride.

[0027] In this context, a polyfluoride is understood to be an adduct of more than one equivalent of HF to a compound containing fluoride ions.

[0028] In the process according to the invention, it can further be provided that the production of the modified isocyanate, in particular the reaction of the monomeric isocyanate in the presence of the catalyst to form a reaction mixture (a), is carried out in the presence of a solvent.

[0029] In principle, all known mono-, di-, tri- or poly-isocyanates can be used as monomeric isocyanates according to the invention, either individually or in any mixtures with each other, to carry out the process according to the invention.

[0030] Examples include: pentamethylene diisocyanate (PDI), hexamethylene diisocyanate (HDI), 2-methylpentane-1,5-diisocyanate (MPDI), 2,4,4-trimethyl-1,6-hexane diisocyanate and 2,2,4-trimethyl-1,6-hexane diisocyanate (TMDI), 4-isocyanatomethyl-1,8-octane diisocyanate (nonane triisocyanate, NTI), 3(4)-isocyanatomethyl-1-methylcyclohexyl diisocyanate (IMCI), isophorone diisocyanate (IPDI), 1,3- and 1,4-bis(isocyanatomethyl)benzene (XDI), 1,3- and 1,4-bis(isocyanatomethyl)cyclohexane (H6XDI), norbornane diisocyanate (NBDI), 2,4- and 2,6-toluene diisocyanate (TDI), bis(4-isocyanatophenyl)methane (4,4'MDI). 4-Isocyanatophenyl-2-isocyanatophenylmethane (2,4'MDI) and multinucleated products accessible by formaldehyde-aniline polycondensation and subsequent conversion of the resulting (poly)amines into the corresponding (poly)isocyanates (polymer MDI).

[0031] Aromatic diisocyanates are preferred, i.e., diisocyanates in which both NCO groups are bonded to an sp2-hybridized carbon atom, or aliphatic diisocyanates, i.e., diisocyanates in which both NCO groups are bonded to an sp3-hybridized carbon atom.

[0032] It is irrelevant by which methods the aforementioned monomeric isocyanates are generated, i.e., with or without the use of phosgene.

[0033] In one embodiment of the invention, the monomeric isocyanate has an NCO functionality greater than 1.0, preferably 2.0, particularly preferably between 2.0 and 3.0.

[0034] In one embodiment of the invention, the monomeric isocyanate is an aliphatic monomeric isocyanate or an aromatic monomeric isocyanate, preferably an aliphatic monomeric isocyanate.

[0035] In one embodiment of the invention, the monomeric isocyanate is an aliphatic monomeric isocyanate, and the aliphatic monomeric isocyanate is one or more compounds selected from the group consisting of pentamethylene diisocyanate (PDI), hexamethylene diisocyanate (HDI), 2-methylpentane-1,5-diisocyanate, 2,4,4-trimethyl-1,6-hexane diisocyanate, 2,2,4-trimethyl-1,6-hexane diisocyanate, 4-isocyanatomethyl-1,8-octane diisocyanate, 3(4)-isocyanatomethyl-1-methylcyclohexyl isocyanate (IMCI), isophorone diisocyanate (IPDI), 1,3- and 1,4-bis(isocyanatomethyl)benzene (XDI), 1,3- and 1,4-bis(isocyanatomethyl)cyclohexane (H6XDI).

[0036] According to the invention, in step a) a monomeric isocyanate is reacted in the presence of a catalyst to form a reaction mixture (a).

[0037] The amount of spirocyclic ammonium salt to be used as a catalyst in the process according to the invention depends primarily on the monomeric isocyanate used and the desired reaction rate and is preferably between > 0.001 and < 5 mol%, preferably between > 0.002 and < 2 mol%, based on the sum of the amounts of substance of the monomeric isocyanate and the catalyst used.

[0038] The spirocyclic ammonium salt can be used as a catalyst in the process or catalyst kit according to the invention, either undiluted or dissolved in solvents. Suitable solvents include any compounds that do not react with the catalyst and are capable of dissolving it sufficiently, e.g., halogenated, aliphatic, or aromatic hydrocarbons, alcohols, ketones, esters, and ethers. Alcohols are preferred.

[0039] The process according to the invention can be carried out in the temperature range of 0 °C to + 250 °C, preferably 20 °C to 200 °C, particularly preferably 40 °C to 150 °C and can be interrupted at any degree of conversion, preferably after 5 to 80%, particularly preferably 10 to 60% of the isocyanate used has been converted.

[0040] In one embodiment of the process according to the invention, in step b) the reaction of the reaction mixture (a) is stopped when a predetermined degree of conversion is reached, based on the total amount of NCO groups of the monomeric isocyanate, by adding a stopper component, wherein the stopper component has a pKa value below 4.0 and is different from HF, forming a reaction mixture (b).

[0041] In a preferred embodiment of the method according to the invention, in step b) the stopper component is added in an equimolar or sub-equimolar, preferably sub-equimolar, amount relative to the molar amount of the spirocyclic ammonium salt. Here, the stopper component preferably has a pKa value below 4.0 and is different from HF.

[0042] In one embodiment of the process according to the invention, the stopper component is selected in step b) from the group comprising or consisting of alkane and arylsulfonic acids, such as napthalene mono- and disulfonic acids, toluenesulfonic acid, dodecylbenzenesulfonic acid, methanesulfonic acid, phosphoric acid and acidic esters of phosphoric acid, such as dibutyl phosphate and / or monobutyl phosphate, as well as any mixtures of the aforementioned compounds, preferably aromatic sulfonic acids and particularly preferably dodecylbenzenesulfonic acid and toluenesulfonic acid. In one embodiment of the process according to the invention, the reaction is stopped by adding the stopper component when a degree of conversion of the monomeric isocyanate of 5 to 80 wt., preferably 5 to 60 wt.%, is reached.

[0043] In one embodiment of the process according to the invention, unreacted monomeric isocyanate from the reaction mixture (b) after step b) is separated in step c). Any prior art process is suitable for this purpose, such as (thin-film) distillation or extraction, wherein the separated monomeric isocyanate is preferably subsequently reused (recycled).

[0044] In one embodiment of the method according to the invention, a stabilizer component according to step c) is added in step d), wherein the stabilizer component added in step d) is added together with the stopper component added in step b) in an equimolar or subequimolar, preferably subequimolar, amount, based on the molar amount of the spirocyclic ammonium salt.

[0045] In one embodiment of the method according to the invention, the stabilizer component is identical or different, preferably identical, to the stopper component.

[0046] In a preferred embodiment of the method according to the invention, the stabilizer component has a pKa value below 4.0 and is different from HF.

[0047] In one embodiment of the process according to the invention, the stabilizer component is selected from the group comprising or consisting of alkane and arylsulfonic acids such as e.g. napthalene mono- and disulfonic acids, toluenesulfonic acid, dodecylbenzenesulfonic acid, methanesulfonic acid, phosphoric acid and acidic esters of phosphoric acid, such as dibutyl phosphate and / or monobutyl phosphate, as well as any mixtures of the aforementioned compounds, preferably aromatic sulfonic acids and particularly preferably dodecylbenzenesulfonic acid and toluenesulfonic acid.

[0048] A further object of the invention is a catalyst kit for isocyanate modification, comprising two separate components comprising the spirocyclic ammonium salt and the stopper component, wherein i) the spirocyclic ammonium salt includes at least one charge-bearing nitrogen atom which is part of two different ring systems (I) and (II), wherein the different ring systems (I) and (II) each consist of C2-C20 alkylene chains, wherein the respective alkylene chains may optionally be interrupted by heteroatoms such as oxygen, nitrogen or sulfur in the alkylene chain, wherein at least one alkylene chain of the two different ring systems (I) and (II) contains at least one, preferably at least two, particularly preferably two to four and most preferably two or three exocyclic substituents other than H, wherein the at least one, preferably the at least two,particularly preferably the two to four and most preferably the two or three substituents other than H are bonded via a carbon-carbon bond, preferably a carbon-carbon single bond to at least one carbon atom, preferably at least two different carbon atoms, particularly preferably two to four different carbon atoms and most preferably two or three different carbon atoms of the C2-C20 alkylene chains of the ring system (I) and / or (II); ii) the stopper component has a pKa value below 4.0 and is different from HF.

[0049] In one embodiment of the invention, the stopper component is selected from the group comprising or consisting of alkane and arylsulfonic acids such as e.g. napthalene mono- and disulfonic acids, toluenesulfonic acid, dodecylbenzenesulfonic acid, methanesulfonic acid, phosphoric acid and acidic esters of phosphoric acid, such as dibutyl phosphate and / or monobutyl phosphate, as well as any mixtures of the aforementioned compounds, preferably aromatic sulfonic acids and particularly preferably dodecylbenzenesulfonic acid and toluenesulfonic acid.

[0050] In one embodiment of the invention, the catalyst kit also includes the stabilizer component described above, wherein the sum of the added stopper and stabilizer components is equimolar with respect to the molar amount of the spirocyclic ammonium salt.

[0051] Another object of the invention is the use of the catalyst kit according to the invention in isocyanate modification to prevent turbidity in the modified isocyanate.

[0052] Also included is the use of a spirocyclic ammonium salt for the preparation of a modified isocyanate, wherein the spirocyclic ammonium salt contains at least one charge-bearing nitrogen atom which is part of two different ring systems (I) and (II), wherein the different ring systems (I) and (II) each consist of C2-C20 alkylene chains, wherein the respective alkylene chains may optionally be interrupted by heteroatoms such as oxygen, nitrogen or sulfur in the alkylene chain, wherein at least one alkylene chain of the two different ring systems (I) and (II) contains at least one, preferably at least two, particularly preferably two to four and most preferably two or three exocyclic substituents other than H, wherein the at least one, preferably the at least two,Particularly preferably, two to four, and most preferably two or three, different H substituents are bonded via a carbon-carbon bond, preferably a carbon-carbon single bond, to at least one carbon atom, preferably at least two different carbon atoms, particularly preferably two to four different carbon atoms, and most preferably two or three different carbon atoms of the C2-C20 alkylene chains of ring system (I) and / or (II), as described in the present invention. The modification process according to the invention generally provides access to a wide range of high-quality modified isocyanates, which are therefore very valuable for the polyurethane sector.

[0053] Another object of the present invention is a modified isocyanate obtainable or produced by the inventive method.

[0054] Depending on the starting (di)isocyanate used and the reaction conditions, the process according to the invention yields polyisocyanates of the so-called isocyanate trimer type (i.e., containing isocyanurate and / or iminooxadiazindeione structures) with a low proportion of uretdione groups ("isocyanate dimers"). The proportion of the latter in the process products generally increases with increasing reaction temperature.

[0055] Polyisocyanates containing high levels of iminooxadiazindeione groups, which are accessible according to the invention by polyfluoride catalysis, are preferred. The term "high levels of iminooxadiazindeione groups" is to be understood as at least 30 mol%, preferably >35 mol%, and particularly preferably >40 mol%, based on the sum of isocyanurate and iminooxadiazindeione groups. The aforementioned molar ratios can be determined, for example, by NMR spectroscopy (see example section).

[0056] The products or product mixtures obtainable according to the inventive process thus represent versatile starting materials for the production of, optionally foamed, plastics, as well as paints, coatings, adhesives, and additives. Therefore, the use of the modified isocyanates according to the invention for the production of foamed or non-foamed plastics, as well as paints, coatings, adhesives, and additives, is a further object of the present invention. Consequently, polyurethane bodies, obtainable or produced by reacting at least one monomeric diisocyanate and / or polyisocyanate with at least one polyol component in the presence of the catalyst component according to the invention, are a further object of the invention. In the case of foamed polyurethane bodies, PIR foams are preferred.

[0057] The process products according to the invention can be used as such or in combination with other isocyanate derivatives of the prior art, such as polyisocyanates containing uretdione, biuret, allophane, isocyanurate and / or urethane groups, whose free NCO groups have optionally been deactivated with blocking agents.

[0058] Further aspects of the present invention include one- or two-component systems comprising a component A) comprising at least one modified isocyanate according to the invention, and a component B) comprising at least one NCO-reactive compound, as well as a coating obtainable or produced by curing a one- or two-component system according to the invention, optionally under the influence of heat and / or in the presence of a catalyst, and also substrates coated with at least one one- or two-component system according to the invention, optionally cured under the influence of heat. The surprising observation that the modified isocyanates according to the invention do not exhibit any turbidity – even if it develops with a delay – makes it clear that the products according to the invention must differ from the prior art in structure and composition.The modified isocyanates according to the invention differ from the prior art systems by the presence of the spirocyclic ammonium salt cation. These differences are reflected in the hardened or foamed polyurethane bodies; thus, a composite component comprising a material that is at least partially bonded to a polyurethane body or a coating according to the invention is also part of the invention.

[0059] In the present context, the term "modified isocyanate" has the meaning defined above and preferably refers to a polyisocyanate which, on average, has at least 1.5 NCO groups. The modified isocyanate according to the invention is synonymous with a modified isocyanate composition, since, for example, the cations and anions are not separably contained.

[0060] A first embodiment of the invention relates to a process for the production of a modified isocyanate comprising a) the reaction of a monomeric isocyanate in the presence of a catalyst to form a reaction mixture (a), wherein the catalyst comprises at least one spirocyclic ammonium salt containing at least one spirocyclic ammonium cation and at least one anion, wherein the spirocyclic ammonium cation includes at least one charge-bearing nitrogen atom which is part of two different ring systems (I) and (II), wherein the different ring systems (I) and (II) each consist of C2-C20 alkylene chains, wherein the respective alkylene chains may optionally be interrupted by heteroatoms such as oxygen, nitrogen or sulfur in the alkylene chain, wherein at least one alkylene chain of the two different ring systems (I) and (II) comprises at least one, preferably at least two,particularly preferably two to four and very preferably two or three exocyclic substituents other than H, wherein the at least one, preferably the at least two, particularly preferably the two to four and very preferably the two or three substituents other than H is bonded via a carbon-carbon bond, preferably a carbon-carbon single bond, to at least one carbon atom, preferably at least two different carbon atoms, particularly preferably two to four different carbon atoms and very preferably two or three different carbon atoms of the C2-C20 alkylene chains of the ring system (I) and / or (II).

[0061] A second embodiment of the invention relates to a method according to the first embodiment, wherein the ring system (I) is composed of 3 to 5 atoms, preferably 4 to 5 atoms and particularly preferably 5 atoms, the spirocyclic ammonium cation being counted in each case.

[0062] A third embodiment of the invention relates to a method according to the first or second embodiment, wherein the ring system (II) is composed of 6 to 8 atoms, preferably 6 to 7 atoms and particularly preferably of 6 atoms, the spirocyclic ammonium cation being counted in each case.

[0063] A fourth embodiment of the invention relates to a process according to one of the first to third embodiments, wherein the respective alkylene chains contain only carbon and hydrogen. A fifth embodiment of the invention relates to a process according to one of the first to fourth embodiments, wherein the at least one substituent other than H is a branched or unbranched alkyl group, a branched or unbranched cycloalkyl group, and / or a substituted or unsubstituted aryl group, preferably a branched or unbranched alkyl group.

[0064] A sixth embodiment of the invention relates to a method according to one of the first to fifth embodiments, wherein the at least one substituent other than H is a branched or unbranched alkyl group.

[0065] A seventh embodiment of the invention relates to a method according to the sixth embodiment, wherein the branched or unbranched alkyl group contains 1 to 20 C atoms, preferably 1 to 10 C atoms.

[0066] An eighth embodiment of the invention relates to a method according to one of the first to seventh embodiments, wherein the ring system (II) contains the at least one, preferably the at least two, particularly preferably the two to four and most particularly preferably the two or three exocyclic substituents other than H.

[0067] A ninth embodiment of the invention relates to a method according to one of the first to eighth embodiments, wherein the ring system (II) is composed of 6 to 8 atoms, preferably 6 to 7 atoms and particularly preferably of 6 atoms, and comprises two to four, preferably two or three, exocyclic substituents other than H, each with a branched or an unbranched, preferably an unbranched alkyl group, wherein the branched or unbranched alkyl group contains 1 to 10, preferably 2 to 6, C atoms.

[0068] A tenth embodiment of the invention relates to a method according to the ninth embodiment, wherein the calculated molar mass of a branched or unbranched, preferably an unbranched alkyl group is greater than that of at least one further branched or unbranched, preferably an unbranched further alkyl group.

[0069] An eleventh embodiment of the invention relates to a method according to any one of the first to tenth embodiments, wherein the ring system (I) is composed of 3 to 5 atoms, preferably 4 to 5 atoms, and particularly preferably 5 atoms, and contains no exocyclic substituents other than hydrogen. A twelfth embodiment of the invention relates to a method according to any one of the first to eleventh embodiments, wherein the anion is selected from the group consisting of hydroxide, alkanoate, carboxylate, heterocycles with at least one negatively charged nitrogen atom in the ring, fluoride, hydrogen difluoride, higher polyfluorides, adducts of more than one equivalent of HF to compounds containing fluoride ions, and any mixtures of the aforementioned, preferably hydrogen difluoride and / or dihydrogen trifluoride.

[0070] A thirteenth embodiment of the invention relates to a method according to one of the first to twelfth embodiments, wherein the monomeric isocyanate has an NCO functionality of >1.0, preferably of 2.0, particularly preferably of 2.0-3.0.

[0071] A fourteenth embodiment of the invention relates to a method according to one of the first to thirteenth embodiments, wherein the monomeric isocyanate is an aliphatic monomeric isocyanate or aromatic monomeric isocyanate, preferably an aliphatic monomeric isocyanate.

[0072] A fifteenth embodiment of the invention relates to a process according to one of the first to fourteenth embodiments, wherein the monomeric isocyanate is an aliphatic monomeric isocyanate and the aliphatic monomeric isocyanate is one or more compounds selected from the group consisting of pentamethylene diisocyanate (PDI), hexamethylene diisocyanate (HDI), 2-methylpentane-1,5-diisocyanate, 2,4,4-trimethyl-1,6-hexane diisocyanate, 2,2,4-trimethyl-1,6-hexane diisocyanate, 4-isocyanatomethyl-1,8-octane diisocyanate, 3(4)-isocyanatomethyl-1-methylcyclohexyl isocyanate (IMCI), isophorone diisocyanate (IPDI), 1,3- and 1,4-bis(isocyanatomethyl)benzene (XDI), 1,3- and 1,4-bis(isocyanatomethyl)cyclohexane (H6XDI).

[0073] A sixteenth embodiment of the invention relates to a method according to one of the first to fifteenth embodiments comprising: b) the conversion of the reaction mixture (a) upon reaching a predetermined degree of conversion, based on the total amount of NCO groups of the monomeric isocyanate, by adding a stopper component, wherein the stopper component has a pK s -value below 4.0 and is different from HF, is stopped by forming a reaction mixture (b).

[0074] A seventeenth embodiment of the invention relates to a method according to the sixteenth embodiment, wherein the stopper component is added in an equimolar or subequimolar, preferably subequimolar, amount relative to the molar amount of the spirocyclic ammonium salt.

[0075] An eighteenth embodiment of the invention relates to a method according to the sixteenth or seventeenth embodiment, wherein the stopper component has a pKs -value below 4.0. A nineteenth embodiment of the invention relates to a method according to one of the sixteenth to eighteenth embodiments, wherein the stopper component is selected from the group comprising or consisting of alkane and aryl sulfonic acids such as napthalene mono- and disulfonic acids, toluenesulfonic acid, dodecylbenzenesulfonic acid, methanesulfonic acid, phosphoric acid and acidic esters of phosphoric acid, such as dibutyl phosphate and / or monobutyl phosphate, as well as any mixtures of the aforementioned compounds, preferably of aromatic sulfonic acids and particularly preferably of dodecylbenzenesulfonic acid and toluenesulfonic acid.

[0076] A twentieth embodiment of the invention relates to a process according to one of the sixteenth to nineteenth embodiments, wherein the reaction is stopped by adding the stopper component when a conversion degree of the monomeric isocyanate of 5 to 80 wt.%, preferably 10 to 60 wt.%, is reached.

[0077] A twenty-first embodiment of the invention relates to a method according to one of the sixteenth to twentieth embodiments comprising: c) separation of unreacted monomeric isocyanate from the reaction mixture (b) after step b)

[0078] A twenty-second embodiment of the invention relates to a method according to the twenty-first embodiment comprising: d) adding a stabilizer component according to step c), wherein the stabilizer component added in step d) is added together with the stopper component added in step b) in an equimolar or subequimolar, preferably subequimolar, amount, based on the molar amount of the spirocyclic ammonium salt.

[0079] A twenty-third embodiment of the invention relates to a method according to the twenty-second embodiment, wherein the stabilizer component is identical or different, preferably identical, to the stopper component.

[0080] A twenty-fourth embodiment of the invention relates to a method according to the twenty-second or twenty-third embodiment, wherein the stabilizer component has a pK s -value below 4.0.

[0081] A twenty-fifth embodiment of the invention relates to a process according to one of the twenty-second to twenty-fourth embodiments, wherein the stabilizer component is selected from the group comprising or consisting of alkane and aryl sulfonic acids, such as napthalene mono- and disulfonic acids, toluenesulfonic acid, dodecylbenzenesulfonic acid, methanesulfonic acid, phosphoric acid and acidic esters of phosphoric acid, such as dibutyl phosphate and / or monobutyl phosphate, as well as any mixtures of the aforementioned compounds, preferably of aromatic sulfonic acids and particularly preferably of dodecylbenzenesulfonic acid and toluenesulfonic acid. A twenty-sixth embodiment of the invention relates to a catalyst kit for isocyanate modification, comprising two separate components comprising the spirocyclic ammonium salt and the stopper component, wherein (i) the spirocyclic ammonium salt includes at least one charge-bearing nitrogen atom,which is part of two different ring systems (I) and (II), wherein the different ring systems (I) and (II) each consist of C2-C20 alkylene chains, wherein the respective alkylene chains may optionally be interrupted by heteroatoms such as oxygen, nitrogen or sulfur in the alkylene chain, wherein at least one alkylene chain of the two different ring systems (I) and (II) contains at least one, preferably at least two, particularly preferably two to four and most preferably two or three exocyclic substituents other than H, wherein the at least one, preferably the at least two, particularly preferably the two to four and most preferably the two or three substituents other than H are linked via a carbon-carbon bond, preferably a carbon-carbon single bond, to at least one carbon atom, preferably at least two different carbon atoms.particularly preferably two to four different carbon atoms and most preferably two or three different carbon atoms of the C2-C20 alkylene chains of the ring system (I) and / or (II) are bonded; ii) the stopper component has a pKa value below 4.0 and is different from HF.

[0082] A twenty-seventh embodiment of the invention relates to a catalyst kit according to the twenty-sixth embodiment, wherein the stopper component is selected from the group comprising or consisting of alkane and arylsulfonic acids such as e.g. napthalene mono- and disulfonic acids, toluenesulfonic acid, dodecylbenzenesulfonic acid, methanesulfonic acid, phosphoric acid and acidic esters of phosphoric acid, such as dibutyl phosphate and / or monobutyl phosphate, as well as any mixtures of the aforementioned compounds, preferably of aromatic sulfonic acids and particularly preferably of dodecylbenzenesulfonic acid and toluenesulfonic acid.

[0083] A twenty-eighth embodiment of the invention relates to the use of the catalyst kit according to claim twenty-sixth or twenty-seventh embodiment in isocyanate modification to prevent turbidity in the modified isocyanate.

[0084] A twenty-ninth embodiment of the invention relates to the use of a spirocyclic ammonium salt for the production of a modified isocyanate, wherein the spirocyclic ammonium salt comprises at least one charge-bearing nitrogen atom which is part of two different ring systems (I) and (II), wherein the different ring systems (I) and (II) each consist of C2-C20 alkylene chains, wherein the respective alkylene chains may optionally be interrupted by heteroatoms such as oxygen, nitrogen, or sulfur in the alkylene chain, wherein at least one alkylene chain of the two different ring systems (I) and (II) contains at least one, preferably at least two, particularly preferably two to four, and most preferably two or three, exocyclic substituents other than H, wherein the at least one, preferably the at least two,particularly preferably the two to four and most preferably the two or three substituents other than H are bonded via a carbon-carbon bond, preferably a carbon-carbon single bond to at least one carbon atom, preferably at least two different carbon atoms, particularly preferably two to four different carbon atoms and most preferably two or three different carbon atoms of the C2-C20 alkylene chains of the ring system (I) and / or (II).

[0085] A thirtieth embodiment of the invention relates to a modified isocyanate, obtainable or produced, preferably directly obtainable, by a method according to one of the first to twenty-fifth embodiments.

[0086] A thirty-first embodiment of the invention relates to a one-component system comprising a modified isocyanate according to the thirty-first embodiment in which the NCO groups are blocked, or a two-component system comprising a component 1), comprising at least one modified isocyanate according to the thirty-first embodiment, and a component 2), comprising at least one compound reactive towards NCO groups.

[0087] A thirty-second embodiment of the invention relates to a coating obtainable or produced by applying a one- or two-component system according to the thirty-first embodiment to a substrate and curing, optionally under the influence of heat and / or in the presence of a catalyst.

[0088] A thirty-third embodiment of the invention relates to a composite component comprising a material which is at least partially combined with a coating according to the thirty-second embodiment.

[0089] Measurement methods

[0090] The present invention will be explained in more detail below by means of examples and comparative examples, without, however, limiting it to these.

[0091] Unless otherwise stated, all percentages are to be understood as weight percentages.

[0092] The NCO content was determined by titration according to DIN EN ISO 11909:2007-05.

[0093] The assessment of solubility / turbidity is carried out qualitatively by visual inspection, whereby larger particles are detected, as well as with a device from the company Hach, whereby values ​​above 1.5 TE(F) are considered unacceptable.

[0094] Unless otherwise stated, all reactions were carried out under a nitrogen atmosphere.

[0095] The diisocyanates used are products of Covestro Deutschland AG, D-51368 Leverkusen; all other commercially available chemicals were sourced from Sigma Aldrich Chemie GmbH, Eschenstrasse 5 in D-82024 Taufkirchen.

[0096] The UPAC names of the catalysts used were generated with the ChemDraw Professional program from Perkin Eimer, version 20.1.1.125, and manually translated into German.

[0097] Examples 1 to 15: Production of spirocyclic ammonium salts with different cations and anions (partly according to the invention)

[0098] Step i): general manufacturing procedure for the preparation of spirocyclic ammonium chlorides using the non-inventive example of 5-azaspiro[4.5]decane-5-ium chloride (see also Table 1, entry 2)

[0099] In a 2 1 four-necked flask with stirrer and intensive condenser, 61.7 g (1.1 mol) KOH, 500 ml water (deionized) and 139.7 g (1.1 mol) 1,4-dichlorobutane were placed together and heated to approximately 100-110°C oil bath temperature while stirring (weak reflux).

[0100] After reaching the specified internal temperature, 85.2 g (1 mol) of piperidine were added rapidly to prevent excessive reflux. Solid deposition began shortly after the piperidine was added. The reaction mixture was heterogeneous from the start (initially liquid-liquid, then three-phase liquid-liquid-solid, then solid-liquid), but always contained enough liquid phase for efficient mixing of the majority of the reaction mass. More water can be added if necessary.

[0101] After complete addition of piperidine, the mixture was stirred for two hours at an oil bath temperature of 110–120°C. The reflux decreased noticeably during this period.

[0102] Subsequently, using a rotary evaporator, with successively increasing bath temperature and successively decreasing pressure adapted to the amount of distillate, all volatile components were separated until the end at 0.1 mbar, 150°C, and the nearly colorless, solid residue was taken up in 2-propanol, thoroughly homogenized under reflux with stirring, filtered, and the precipitate was washed with boiling 2-propanol until only KCl remained (dried under vacuum: 73.1 g, 98% of theory).

[0103] The solution of the spirocyclic ammonium salt, 5-azaspiro[4.5]decane-5-nium chloride, was concentrated to approximately 60% solids using a rotary evaporator, whereby crystallization began after cooling to room temperature and was further completed in the refrigerator.

[0104] By filtration, further concentration of the resulting mother liquors and processing as described above, drying of the resulting colorless, well crystallizing solids in a vacuum (3 h, 150°C, 0.1 mbar) a total of 149.3 g (85% of theory) of analytically pure 5-azaspiro[4.5]decane-5-nium chloride was obtained, which was used for the further reactions (anion exchange).

[0105] The other spirocyclic ammonium salts, some of which are according to the invention, were obtained by analogy to the above manufacturing procedure.

[0106] The necessary substituted piperidine derivatives, if not commercially available, were obtained by nuclear hydrogenation of the corresponding pyridine derivatives, as exemplified here by the hydrogenation of 4-tert-butylpyridine to 4-tert-butylpiperidine (mixture of isomers):

[0107] In a stirred 31-liter high-pressure reactor (V4A stainless steel), 1 kg (7.4 mol) of 4-tert-butylpyridine was dissolved in 750 ml of methylcyclohexanone under stirring (800 rpm). 90 g of the catalyst Rh / C (5% charge, Aldrich, Cat. No. 206164) was then added. The reactor was inerted three times with 5 bar nitrogen. Subsequently, 50 bar of hydrogen was applied, the mixture was slowly heated to 160°C under stirring, the hydrogen pressure was increased to 100 bar, and hydrogenation continued until no more hydrogen was absorbed. After cooling and depressurization, the resulting reaction mixture was filtered from the catalyst and completely desulfurized using a rotary evaporator. 914 g of a slightly yellowish liquid remained, which was distilled under vacuum: oil bath 100–105°C, head 67–69°C at 3 mbar. Yield: 870.4 g (83% of theory). The ¹H NMR analysis confirmed the structure of the product.

[0108] The non-commercially available, multiply substituted pyridine derivatives were obtained in accordance with RU 2334739, as exemplified here by the synthesis of 3,5-diethyl-5-propylpyridine, which, after hydrogenation as described above and conversion to the spiro cycle according to the general manufacturing procedure, yields the species shown in Table 1, entry 12 (as a mixture of stereoisomers).

[0109] The reaction was carried out in a 4 L, 4-necked flask. 1600 mL of butanal was placed in the flask and cooled to 0°C with stirring. 400 mL of 28% aqueous ammonia solution were added within a few minutes while cooling and stirring vigorously. The reaction mixture was then transferred to a separatory funnel, and after phase separation, the lower, aqueous phase was drained off and discarded. The upper, organic phase was returned to the reaction flask, and a solution of 54 g of praseodymium(III) nitrate hexahydrate in 608 mL of dimethyl methacrylate (DMF) was added. The reaction mixture was stirred at room temperature for 24 h and then extracted with three 300 mL diethyl ether extracts. The combined ethereal extracts were dried with magnesium sulfate chlorine and concentrated by rotary evaporation. The remaining viscous, yellow-orange liquid was then distilled using a thin-film evaporator at a jacket temperature of 160°C and a pressure of 0.15 mbar. The resulting yellow distillate (711 g, 46% of theoretical value)) 3,5-Diethyl-5-propylpyridine (isomer mixture) were subsequently hydrogenated without further purification as described above.

[0110] To obtain derivatives that are substituted in the ring system newly formed by the cyclization reaction, a four-step route starting from nitroalkanes and maleic esters is suitable, which is described below using the synthesis of 2-isopropyl-1,4-dichlorobutane (IUP AC name: 1-chloro-3-(chloromethyl)-4-methylpentane) as an example, which is required, for example, for the preparation of cations 9 and 10 in Table 1.

[0111] Reaction scheme:

[0112] In a 41 4-inch necked flask, 178 g of 2-nitropropane and 288 g of dimethyl maleate were placed in 2500 ml of acetonitrile and stirred at room temperature. 310 g of 8-diazabicyclo[5,4,0]undec-7-ene (DBU) were added at room temperature, ensuring the internal temperature did not exceed 30°C. Stirring continued at room temperature for 7 hours. 500 g of silica gel (Merck 0.04–0.063 mm) were stirred into the resulting yellowish, transparent solution and filtered off. The filtrate was ionized by rotary evaporation, and the remaining yellow solid was subjected to chromatographic purification using a 2:1 ratio of toluene to ethanol. The fraction containing the product was then desulfurized by rotary evaporation. 367.7 g (98.8% of theory) of dimethyl isopropylidene succinic acid remained as a colorless liquid (structure determined by 'H- and 13(Confirmed by C-NMR). The latter was placed in a 21-liter hydrogenation reactor made of V4A stainless steel with a stirrer, dissolved in 700 ml of ethyl acetate, and mixed with 20 g of catalyst Pd / C (charge 10%) while stirring (800 rpm). After three inerting cycles with 5 bar nitrogen and a pressure test with 30 bar nitrogen with the stirrer switched off, the stirrer was reinserted and the pressure adjusted to 5 bar hydrogen. The mixture was then slowly heated to 35 °C and hydrogenation continued until hydrogen uptake ceased. After cooling, the pressure was reduced, the reaction solution was filtered, and the solvent was removed using a rotary evaporator. 318.5 g of a slightly yellowish liquid remained, which was then distilled under vacuum. Oil bath temperature: 100–115 °C; head temperature: 55–67 °C at 0.05–0.1 mbar. Yield of isopropyl succinic acid dimethyl ester (structure confirmed by 'H-NMR'): 300.2 g (81.0% of theory).

[0113] In a 4 L, 4-necked flask, 1200 mL of anhydrous diethyl ether was placed. 50 g of LiAlH4 was added portionwise while stirring and dissolved. A solution of 99.2 g of dimethyl isopropyl succinate in 400 mL of diethyl ether was then slowly added dropwise. The reaction mixture was stirred for 6 h at room temperature and left to stand overnight. 1000 mL of water was added slowly and very carefully, and the pH was then adjusted to 2-3 with 20% hydrochloric acid. The product was extracted with ethyl acetate (2 x 400 mL). This solution was dried with NaSCl and completely desulfurized using a rotary evaporator. The remaining colorless liquid was distilled under vacuum. Oil bath: 145-150 °C, head: 95-97 °C at 0.2 mbar. Yield: 65.5 g (94.0% of theory) of 2-isopropyl-1,4-butanediol. The structure was confirmed by 1H NMR analysis.

[0114] 205 g of 2-isopropyl-1,4-butanediol were dissolved in 205 g of pyridine in a 4 L four-necked flask, and 729 g of thionyl chloride were slowly added dropwise under external cooling, keeping the temperature of the reaction mixture below 25 °C. A white precipitate initially formed, which dissolved again upon further addition of thionyl chloride. The reaction mixture was stirred for 2 hours at 100 °C (bath), during which time the solution continued to clear and darken. After cooling to room temperature, a 1:1 mixture of ice and water (2330 g total) was added slowly and very carefully, and the mixture was stirred for another hour after it had been completely added. The product was extracted with diethyl ether (3 x 300ml) and the concentrated extracts were washed and neutralized with 50% sulfuric acid and then with sodium bicarbonate solution, dried with MgSCL and completely freed from solvent on a rotary evaporator.After vacuum distillation (oil bath 115°C, head: 44-45°C at 0.02mbar) 220.8 g (84.2% of theory) were obtained. 1 H-NMR analysis of pure 2-isopropyl-1,4-dichlorobutane (1UPAC name: 1-chloro-3-(chloromethyl)-4-methylpentane).

[0115] The catalysts listed in Table 1 were synthesized from the primarily formed chloride by anion exchange (optionally followed by HF addition for the synthesis of the di / polyfluorides) according to Examples 1 to 4 on page 10 of WO 2017 / 029266 Al.

[0116] Example 16: Method for modifying HDI using the non-inventive spirocyclic ammonium salt 5-azaspiro[4.5]decan-5-ium hydrogen difluoride (cation see Table 1, row 2, anion: [HF] '; comparison)

[0117] In a double-walled, ground-glass vessel with a stirrer, connected to an inert gas system (nitrogen / vacuum) and a thermometer, 1000 g of HDI were placed at an internal temperature of 60°C and stirred under vacuum (< 1 mbar) for one hour to remove dissolved gases. After aeration with nitrogen, a 30% solution of 5-azaspiro[4.5]decan-5-ium hydrogen difluoride in 2-propanol was added dropwise to allow the reaction to be carried out in the temperature range between approximately 59 and 62°C. After approximately 1 mol of NCO groups had reacted, indicated by reaching an NCO content of around 45.8%, the catalyst was deactivated by adding an equivalent amount of dodecylbenzenesulfonic acid, dissolved 50% in 2-ethylhexanol, stirred for a further 30 min at 60°C and then worked up.

[0118] The product was processed by vacuum distillation in a thin-film evaporator, short-path evaporator (KWV), with a pre-evaporator (VV) (distillation data: pressure: 0.1 ± 0.02 mbar, VV temperature: 120 °C, HV temperature: 140 °C), whereby unreacted monomer was separated as distillate and the monomer-poor polyisocyanate resin as bottoms (initial run). The polyisocyanate resin was separated, and the distillate was collected in a second ground-glass joint stirrer, identical in design to the first, and made up to the initial volume (1000 g) with freshly degassed HDI. The process was then catalyzed again and carried out as described above. This procedure was repeated a total of six times.After several recycling steps, it was observed that the amount of catalyst required to achieve the desired conversion was slightly higher in the initial run (0.28 g) than in the subsequent run (0.2 g), but then increased successively (0.21; 0.25; 0.31; 0.45 g).

[0119] Furthermore, particularly in the products of the "later" recycling steps, and often only after several weeks of storage, especially at low temperatures and / or after the addition of typical paint solvents such as xylene or solvent naphtha, a slowly developing turbidity was observed in the polyisocyanate resins, sometimes accompanied by a slow increase in the residual monomer content, especially when stored at higher temperatures. The precipitates obtained after filtration, as determined by combined analytical methods, proved to be essentially a mixture of 5-azaspiro[4.5]decane-5-ium chloride (main component) and 5-azaspiro[4.5]decane-5-ium bromide (minor component, approximately 50% molar relative to the chloride), along with small amounts of other salts containing the 5-azaspiro[4.5]decane-5-ium cation, particularly dodecylbenzenesulfonate.

[0120] Example 17: Process for modifying HDI using the spirocyclic ammonium salt 9-ethyl-6-methyl-5-azaspiro[4.5]dekan-5-ium hydrogendifluoride according to the invention (cation see Table 1, line 6, anion: [HF]2'; according to the invention)

[0121] The procedure was carried out in complete analogy to the one described above, with the sole exception that a 30% solution of the catalyst 9-ethyl-6-methyl-5-azaspiro[4.5]dekan-5-ium hydrogen difluoride in 2-propanol was used.

[0122] Precipitations in the polyisocyanate resins were not observed even after long storage, even at low temperatures, optionally in the presence of typical paint solvents, which is why it can be assumed that the solubility of the halide salts of the 9-ethyl-6-methyl-5-azaspiro[4.5]decane-5-ium cation in the polyisocyanate matrix must be higher than that of the 5-azaspiro[4.5]decane-5-ium cation used in the comparison example.

[0123] This assumption was supported by investigating the solubility of 9-ethyl-6-methyl-5-azaspiro[4.5]decan-5-ium chloride in HDI and IPDI (Table 1, row 6, according to the invention) in comparison with the solubility of chlorides of unsubstituted spiroammonium cations (Table 1, rows 1-3, not according to the invention). Therefore, to further investigate suitable catalysts according to the invention, the solubility of the corresponding chlorides in HDI and IPDI was examined to assess their potential suitability for use according to the invention. The results of these investigations are shown in Table 1.

[0124]

Claims

Patent claims 1. A process for the preparation of a modified isocyanate comprising a. the reaction of a monomeric isocyanate in the presence of a catalyst to form a reaction mixture (a), wherein the catalyst comprises at least one spirocyclic ammonium salt containing at least one spirocyclic ammonium cation and at least one anion, wherein the spirocyclic ammonium cation includes at least one charge-bearing nitrogen atom which is part of two different ring systems (I) and (II), wherein the different ring systems (I) and (II) each consist of C2-C20 alkylene chains, wherein the respective alkylene chains may optionally be interrupted by heteroatoms such as oxygen, nitrogen or sulfur in the alkylene chain, wherein at least one alkylene chain of the two different ring systems (I) and (II) comprises at least one, preferably at least two,particularly preferably two to four and very preferably two or three exocyclic substituents other than H, wherein the at least one, preferably the at least two, particularly preferably the two to four and very preferably the two or three substituents other than H is bonded via a carbon-carbon bond, preferably a carbon-carbon single bond, to at least one carbon atom, preferably at least two different carbon atoms, particularly preferably two to four different carbon atoms and very preferably two or three different carbon atoms of the C2-C20 alkylene chains of the ring system (I) and / or (II).

2. Method according to claim 1, wherein the ring system (II) contains the at least one, preferably the at least two, particularly preferably the two to four and most particularly preferably the two or three exocyclic substituents other than H.

3. Method according to claim 1 or 2, wherein the ring system (II) is composed of 6 to 8 atoms, preferably 6 to 7 atoms and particularly preferably 6 atoms, the spirocyclic ammonium cation being included in each count, and two to four, preferably two or three exocyclic substituents other than H, each with a branched or unbranched, preferably an unbranched alkyl group, wherein the branched or unbranched alkyl group contains 1 to 10, preferably 2 to 6 carbon atoms.

4. Method according to claim 3, wherein the calculated molar mass of a branched or unbranched, preferably an unbranched alkyl group is greater than that of at least one further branched or unbranched, preferably an unbranched further alkyl group.

5. Method according to claims 1 to 4, wherein the ring system (I) is composed of 3 to 5 atoms, preferably 4 to 5 atoms and particularly preferably 5 atoms, wherein the spirocyclic ammonium cation is counted in each case and contains no exocyclic substituents other than H.

6. Method according to any one of claims 1 to 5, wherein the anion is selected from the group consisting of hydroxide, alkanoate, carboxylate, heterocycles with at least one negatively charged nitrogen atom in the ring, fluoride, hydrogen difluoride, higher polyfluorides, adducts of more than one equivalent of HF to compounds containing fluoride ions and any mixtures of the foregoing, preferably hydrogen difluoride and / or dihydrogen trifluoride.

7. A method according to any one of claims 1 to 6 comprising: b) stopping the reaction of the reaction mixture (a) upon reaching a predetermined degree of conversion, based on the total amount of NCO groups of the monomeric isocyanate, by adding a stopper component, wherein the stopper component has a pK s -value below 4.0 and is different from HF, forming a reaction mixture (b).

8. The method according to claim 7 comprising: c) separation of unreacted monomeric isocyanate from the reaction mixture (b) after step b) 9. Catalyst kit for isocyanate modification, comprising two separate components comprising the spirocyclic ammonium salt and the stopper component, wherein i) the spirocyclic ammonium salt includes at least one charge-bearing nitrogen atom which is part of two different ring systems (I) and (II), wherein the different ring systems (I) and (II) each consist of C2-C20 alkylene chains, wherein the respective alkylene chains may optionally be interrupted by heteroatoms such as oxygen, nitrogen or sulfur in the alkylene chain, wherein at least one alkylene chain of the two different ring systems (I) and (II) contains at least one, preferably at least two, particularly preferably two to four and most preferably two or three exocyclic substituents other than H, wherein the at least one, preferably the at least two, particularly preferably the two to four and most preferably the two or three substituents other than H are linked via a carbon-carbon bond, preferably a carbon-carbon single bond, to at least one carbon atom, preferably at least two different carbon atoms,particularly preferably two to four different carbon atoms and most preferably two or three different carbon atoms of the C2-C20 alkylene chains of the ring system (I) and / or (II) are bonded; ii) the stopper component has a pKa value below 4.0 and is different from HF.

10. Catalyst kit according to claim 9, wherein the stopper component is selected from the group comprising or consisting of alkane and arylsulfonic acids such as e.g. napthalene mono- and disulfonic acids, toluenesulfonic acid, dodecylbenzenesulfonic acid, methanesulfonic acid, phosphoric acid and acidic esters of phosphoric acid, such as dibutyl phosphate and / or monobutyl phosphate, as well as any mixtures of the aforementioned compounds, preferably aromatic sulfonic acids and particularly preferably dodecylbenzenesulfonic acid and toluenesulfonic acid.

11. Use of the catalyst kit according to claim 9 or 10 in isocyanate modification to prevent turbidity in the modified isocyanate.

12. Modified isocyanate, obtainable or produced, preferably directly obtainable, by a process according to any one of claims 1 to 10.

13. A one-component system comprising a modified isocyanate according to claim 12 in which the NCO groups are blocked, or a two-component system comprising a component 1), comprising at least one modified isocyanate according to claim 12, and a component 2), comprising at least one compound reactive towards NCO groups.

14. Coating, obtainable or produced by applying a one- or two-component system according to claim 13 to a substrate and curing, optionally under the influence of heat and / or in the presence of a catalyst.

15. Composite component comprising a material that is at least partially combined with a coating according to claim 14.

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