Polyisocyanates with improved properties

Abstract

The invention relates to a method for producing modified isocyanates, in which at least one organic diisocyanate and / or triisocyanate is reacted in the at least temporary presence of a component A1 comprising at least one tetramethylammonium salt and / or at least one cyclic ammonium salt having a cation of formula I, wherein Y is a linear or branched C2-C20 segment which optionally also carries a further substituent and which is optionally interrupted by a heteroatom selected from the group consisting of oxygen, sulfur, nitrogen and an aromatic ring and which optionally contains a further ring, and the substituents R1 and R2 on N are, independently of one another, the same or different, substituted or unsubstituted, optionally branched aliphatic C1-C20 groups, aromatic C6-C20 groups or araliphatic C7-C20 groups, or the substituents R1 and R2 on N together form a ring segment X, to which the same or different definitions mentioned above for Y are applicable; when a predeterminable degree of conversion is achieved based on the total amount of NCO groups of the at least one organic diisocyanate and / or triisocyanate, terminating the reaction by adding a substoichiometric amount, based on the molar amount of the cation of formula (I) in component A1, of component A2 comprising at least one acidic compound having a pKa value of less than 4.0 and different from HF; and, after optional purification, adding to the obtained modified isocyanate a component A3 comprising at least one acidic compound having a pKa value of less than 4.0 and different from HF, the at least one acidic compound of components A2 and A3 being different from each other or identical. # imgabs0 #

Description

[0001] The present invention relates to polyisocyanates having improved properties, such as lack of odor, very low monomer content, good monomer stability, and low tendency to cloud. The present invention also relates to a process for preparing these polyisocyanates having improved properties, to their use for preparing polyurethane objects or coatings, and to polyurethane objects or coatings. The present invention further relates to one-component or two-component systems comprising the polyisocyanates having improved properties.

[0002] The oligomerization or polymerization of isocyanates, in particular to form higher molecular weight oligomer mixtures having uretdione ("dimer"), isocyanurate ("trimer") and / or iminooxadiazinedione structures ("asymmetric trimers") in their molecular structure, has long been known. As can be seen above, the oligomerization or polymerization of isocyanates is based in principle on the same chemical reaction. The mutual reaction of smaller amounts of isocyanates is referred to as oligomerization. The reaction of larger amounts of isocyanates is referred to as polymerization. In the context of the present invention, the oligomerization or polymerization of isocyanates described above is collectively referred to as isocyanate modification or modification of isocyanates.

[0003] If the modified polyisocyanate contains free NCO groups, which can optionally also be temporarily deactivated with blocking agents, it is an exceptionally high-quality raw material for the preparation of a wide variety of polyurethane plastics and coating compositions.

[0004] A number of industrial processes for the modification of isocyanates are already established, in which the isocyanates to be modified (usually diisocyanates) are usually reacted by adding catalysts, which are then deactivated (deactivated) by suitable measures when the desired degree of conversion of the isocyanate to be modified has been reached, and the polyisocyanates obtained are usually separated from the unreacted monomers. An overview of these processes from the prior art can be found in HJ Laas et al., J. Prakt. Chem. 1994, 336, pp. 185 ff.

[0005] Compounds consisting of ions, the cation being important inter alia from the viewpoint of the solubility of the respective salts in the isocyanate medium, have proven to be effective modification catalysts since they can be used in very low amounts relative to the monomer to be converted and bring about the desired result very rapidly.

[0006] WO 2015 / 124504 A1 and WO 2017 / 029266 A1 describe very stable ammonium salts in which the charged nitrogen atom forms part of the ring system. However, these compounds have the disadvantage of poor solubility in isocyanate-functional polyisocyanate resins and can therefore lead to turbidity in the final process product.

[0007] According to the teaching of WO 2021 / 122508 A1, this problem is avoided by introducing a hydroxyl function into the catalyst molecule. However, a disadvantage is that specific hydroxyl-functional ammonium salts are not commercially available and their synthesis is very expensive. Inexpensive hydroxyl-functional ammonium salts (in which the hydroxyl function is not bonded to a carbon atom of a charged nitrogen-containing ring) do not offer any advantages in the context of the present invention: they are not odorless, and the monomers generated and usually recycled in the process are not free of interfering catalyst decomposition products.

[0008] The object of the present invention was therefore to provide polyisocyanates having improved properties, such as odorlessness, a very low monomer content of <0.1% by weight, high redissociation stability and a low tendency to clouding. In particular, the object of the present invention was to provide polyisocyanates having a high content of iminooxadiazinedione structures and the above-mentioned improved properties.

[0009] Taking this need into account, a first subject matter of the present invention relates to a process for preparing modified isocyanates, wherein at least one organic diisocyanate and / or triisocyanate is reacted in the at least temporary presence of a component A1 comprising at least one tetramethylammonium salt and / or at least one cyclic ammonium salt having a cation of formula I,

[0010]

[0011] in

[0012] Y is a straight or branched C2-C1-4-oxo-1 ... 20 chain segment, and

[0013] Substituent R on N 1 and R 2 independently of one another represent identical or different, substituted or unsubstituted, optionally branched aliphatic C1-C 20 Group, aromatic C6-C 20 Group or aromatic aliphatic C7-C 20 group, or

[0014] Substituent R on N 1 and R 2Together, they form a ring segment X, for which the same or different definitions as those mentioned above for Y apply, the reaction is terminated upon reaching a predeterminable degree of conversion, based on the total amount of NCO groups of the at least one organic diisocyanate and / or triisocyanate, by adding a substoichiometric amount of component A2, based on the molar amount of cations of the formula I in component A1, comprising at least one acidic compound having a pKa value of less than 4.0 and different from HF, and adding to the modified isocyanate obtained (optionally after further purification) a component A3 comprising at least one acidic compound having a pKa value of less than 4.0 and different from HF, wherein the at least one acidic compound in components A2 and A3 can be different from or identical to one another.

[0015] Taking this need into account, one subject of the present invention is a catalyst kit for isocyanate modification, comprising three separate components A1, A2 and A3, wherein

[0016] a) component A1 contains at least one tetramethylammonium salt and / or at least one cyclic ammonium salt having a cation of formula I,

[0017]

[0018] in

[0019] Y is a straight or branched C2-C1-4-oxo-1 ... 20 chain segment, and

[0020] Substituent R on N 1 and R 2 independently of one another represent identical or different, substituted or unsubstituted, optionally branched aliphatic C1-C 20 Group, aromatic C6-C 20 Group or aromatic aliphatic C7-C 20 group, or

[0021] Substituent R on N 1 and R 2 together form a ring segment X, for which the same or different definitions as mentioned above for Y apply,

[0022] b) component A2 is used in a substoichiometric amount, based on the molar amount of the cation of the formula I in component A1, and comprises or consists of at least one acidic compound having a pKa value of less than 4.0 and different from HF;

[0023] c) Component A3 contains at least one acidic compound having a pKa value below 4.0 and different from HF, wherein the at least one acidic compound in components A2 and A3 can be different from or identical to one another.

[0024] Taking this need into account, one subject matter of the present invention is the use of at least one catalyst kit according to the invention for modifying isocyanates and for preventing turbidity in modified isocyanates.

[0025] References to "comprising", "containing" etc. preferably mean "consisting essentially of", very particularly preferably to "consisting of". The further embodiments mentioned in the claims and in the description can be combined as desired, in particular within the context of different subjects according to the invention, as long as the context does not clearly indicate otherwise.

[0026] As used herein, "at least one" refers to one or more, for example, two, three, four, five, six, seven, eight, nine or more. With respect to the components of the compounds described herein, this numerical value does not relate to the absolute number of molecules, but rather to the type of component. "At least one cyclic ammonium salt" is therefore understood to mean, for example, that only one type of cyclic ammonium salt or a plurality of different types of cyclic ammonium salts may be contained, rather than specifying the amount of each compound.

[0027] Numerical values ​​without decimal places herein refer to the complete value to the nearest decimal place in each case. For example, "99%" means "99.0%".

[0028] Numerical ranges given in the format "from x to y" include the specified values. If multiple preferred numerical ranges are specified in this format, it is understood that all ranges formed by combinations of the different endpoints are also included.

[0029] For polyacids, the pKa value is considered in the context of the present invention to be the lowest value, for example for phosphoric acid this is pKa1 of 2.16, rather than the other values ​​pKa2=7.20 and pKa3=12.33.

[0030] The term "aliphatic" is defined herein to mean a saturated or unsaturated non-aromatic hydrocarbon group.

[0031] The term "araliphatic" is defined herein to mean a hydrocarbon group consisting of an aromatic hydrocarbon group and a saturated or unsaturated hydrocarbon group directly bonded to the aromatic group.

[0032] The term "alicyclic" or "cycloaliphatic" is defined herein to mean non-aromatic, optionally substituted carbocyclic or heterocyclic compounds or units (e.g., cycloalkanes, cycloalkenes, or oxacycloalkanes, thiacycloalkanes, azacycloalkanes, or thiazacycloalkanes). Specific examples are cyclohexyl, cyclopentyl, and their N- or O-heterocyclic derivatives, such as pyrimidine, pyrazine, tetrahydropyran, or tetrahydrofuran.

[0033] Where a group or compound is disclosed as "optionally substituted" or "substituted", suitable substituents are -F, -Cl, -Br, -I, -OCH3, -OCH2CH3, -O-isopropyl or -O-n-propyl, -OCF3, -CF3, -SC 1-6 -alkyl and / or (optionally via lateral heteroatoms) straight-chain or branched aliphatic and / or alicyclic structural units having 1 to 12 carbon atoms, which in each case serve as a replacement for a carbon-bonded hydrogen atom of the corresponding molecule. Preferred substituents are halogen (especially -F, -Cl), C1-C6 alkoxy (especially methoxy and ethoxy), trifluoromethyl and trifluoromethoxy, which in each case serve as a replacement for a carbon-bonded hydrogen atom of the corresponding molecule.

[0034] According to the invention, component A1 contains at least one tetramethylammonium salt and / or at least one cyclic ammonium salt having a cation of the formula I, wherein cyclic ammonium salts having a cation of the formula I are preferred.

[0035] In a first preferred embodiment, Y represents an alkylene segment which, together with the charged nitrogen atom, comprises four to seven members and optionally carries further substituents.

[0036] In an equally preferred embodiment, R 1 and R 2 Together with the charged nitrogen atom, it represents a ring segment X which is identical to or different from Y, wherein X is a C4-C6 alkylene segment which optionally carries further substituents and may optionally carry further substituents.

[0037] In another preferred embodiment, the segment Y and / or the ring segment X has a linear structure.

[0038] The substituent R on N 1 and R 2 The cations of formula I that together form the ring system or ring segment X are spirocyclic compounds. The latter can be readily obtained by reacting a secondary amine in which the nitrogen atom is part of the ring system with a suitably substituted dihaloalkane and subsequently carrying out anion exchange. A preferred route for their efficient synthesis is apparent from Example 1.

[0039] X and Y in formula I can preferably represent optionally substituted alkylene independently of each other, wherein preferably C4-C6 alkylene chain, especially in two N-central rings.Described C4-C6 alkylene chain preferably has linear structure.These compounds can be easily obtained by reacting pyrrolidine, piperidine and azepane (1H-hexahydroazacycloheptatriene) with optionally substituted 1,4-, 1,5- and 1,6-dihaloalkane, wherein halogen represents Cl, Br and I, preferably Cl.

[0040] Furthermore, representatives having a C chain interrupted by a heteroatom in one of the X or Y segments of the general formula I can also be obtained, for example, by analogous reactions of optionally C-substituted oxazolidines, isoxazolidinones, oxazinanes, morpholines and oxazepanes, as well as analogs of the aforementioned NO-heterocycles containing S instead of O, as well as imidazolidines, pyrazolidines, piperazines and structurally related compounds with the aforementioned dihaloalkanes. Furthermore, in the case of species containing two or more nitrogen atoms, by appropriate modification of the reaction conditions, it is additionally possible to produce salts with bivalent or multivalently charged cations, or by appropriate prior substitution of the nitrogen atom or atoms, it is additionally possible to obtain singly positively charged cations of the formula I, in which one or more exocyclic alkyl substituents are present on one or more trivalent nitrogen atoms of the ring X or Y.

[0041] It goes without saying that structural changes can also be introduced into the ring segments X or Y by suitable choice of the alkylating agent; examples include the reaction of α-ω-dihaloalkyl ethers with the aforementioned secondary amines.

[0042] In a further preferred embodiment, R 1 and R 2 They independently represent the same or different C1-C8 alkyl substituents or the same or different benzyl groups optionally substituted on the aromatic ring, preferably the same or different C1-C6 alkyl substituents, particularly preferably the same or different C1-C6 alkyl substituents having a linear structure, and very particularly preferably a methyl group.

[0043] The anions used in the compounds of the formula I may in principle be all structural types known to be catalytically active towards isocyanates, preferably hydroxide, alkanoate, carboxylate, heterocycles having at least one negatively charged nitrogen atom in the ring, in particular azole, imidazolate, triazole, tetrazolate, fluoride, hydrogen difluoride, higher polyfluorides or mixtures thereof (adducts of more than one equivalent of HF with compounds containing fluoride ions), fluoride, hydrogen difluoride and higher polyfluorides leading, according to the invention, to products having a high content of iminooxadiazinedione groups.

[0044] The catalysts of component A1 that can be used according to the invention can be used individually or in any desired mixtures with one another. For example, depending on the pKa values ​​of the base and the alcohol used, solutions of quaternary ammonium hydroxides in various alcohols exist partially or completely as ammonium salts with alkoxide anions. The equilibrium can be completely shifted towards the complete formation of alkoxides by removing the water of reaction produced by the reaction.

[0045] In the process according to the invention, provision can be made for the oligomerization to be carried out in the presence of a solvent.

[0046] To carry out the process according to the invention, it is possible in principle to use all monoisocyanates, diisocyanates or polyisocyanates known from the prior art, alone or in any desired mixtures with one another.

[0047] Examples include pentamethylene diisocyanate (PDI), hexamethylene diisocyanate (HDI), 2-methylpentane-1,5-diisocyanate (MPDI), 2,4,4-trimethylhexane-1,6-diisocyanate and 2,2,4-trimethylhexane-1,6-diisocyanate (TMDI), 4-isocyanatomethyloctane-1,8-diisocyanate (nonane triisocyanate, NTI), 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), norbornane diisocyanate (NBDI), toluene 2,4- and 2,6-diisocyanate (TDI), bis(4-isocyanatophenyl)methane (4,4'MDI), 4-isocyanatophenyl-2-isocyanatophenylmethane (2,4'MDI) and polycyclic products obtainable by formaldehyde-aniline polycondensation and subsequent conversion of the resulting (poly)amines into the corresponding (poly)isocyanates (polymeric MDI).

[0048] Preference is given to aromatic diisocyanates, i.e., those in which both NCO groups are bonded to sp 2 -diisocyanates on a hybridized carbon atom, or aliphatic diisocyanates, i.e., in which both NCO groups are bonded to sp 3 -Diisocyanates on hybridized carbon atoms.

[0049] Particular preference is given to PDI, HDI, MPDI, TMDI, NTI, IPDI, IMCI, XDI, H6XDI, MDI or NBDI, and very particular preference is given to pentamethylene diisocyanate (PDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), 1,3- and 1,4-bis(isocyanatomethyl)cyclohexane (H6XDI) and / or norbornane diisocyanate (NBDI).

[0050] The method by which the above-mentioned isocyanates are formed, whether with or without phosgene, is immaterial.

[0051] The amount of catalyst of component A1 which can be used in the process according to the invention depends primarily on the organic isocyanate used and the desired reaction rate and is preferably ≧0.001 to ≦5 mol %, preferably ≧0.002 to ≦2 mol %, based on the total molar amount of isocyanate and catalyst used.

[0052] In the method according to the invention or in the catalyst kit according to the invention, the catalyst can be used undiluted or dissolved in a solvent. Useful solvents include all compounds that do not react with the catalyst and can fully dissolve it, such as optionally halogenated aliphatic or aromatic hydrocarbons, alcohols, ketones, esters and ethers. Alcohols are preferably used.

[0053] The process according to the invention can be carried out in a 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.

[0054] The reaction can be stopped by any desired method (hereinafter also referred to as deactivation of the catalyst or termination of the catalytic isocyanate oligomerization), it being essential to the present invention that the chemical deactivation of the catalyst is carried out in at least two steps in order to obtain the product according to the invention having a low tendency to crystallize and a low residual monomer content.

[0055] According to the invention, to terminate the catalytic isocyanate oligomerization, at least one catalyst poison (hereinafter also referred to as "terminator" and generally referred to as component A2) is used in a substoichiometric amount relative to the catalyst used, but sufficient to terminate the catalytic reaction, and after monomer separation (preferably by distillation), a second dose of the same or a different catalyst poison is added as component A3 to the product according to the invention with a low residual monomer content. The amount of component A3 (hereinafter also referred to as "stabilizer") added as the second dose can be freely selected within wide ranges and is preferably added in a stoichiometric, particularly preferably superstoichiometric, molar amount, based on the calculated molar amount of the cation of formula I in component A1 remaining after deducting the amount already present as component A2. The term "superstoichiometric" is preferably understood to mean that no more than twice the molar amount of catalyst poison relative to the molar amount of the cation of formula I needs to be added to component A1.

[0056] Only the measures according to the invention ensure that an odor-neutral, crystal-stable product with a very low monomer content and high re-cleavage stability is produced over a long period of time and at low temperatures and / or when using typical coating solvents for polyisocyanate resins. Furthermore, the process according to the invention benefits from significantly improved process stability due to more uniform catalyst consumption without drift, as well as a low tendency to caking, turbidity, and solids separation in the system.

[0057] Suitable terminators are generally acidic compounds having a pKa value as defined herein and different from HF, for example alkanesulfonic acids and arylsulfonic acids, such as naphthalenemonosulfonic acid and naphthalenedisulfonic acid, toluenesulfonic acid, dodecylbenzenesulfonic acid, methanesulfonic acid, phosphoric acid and acidic esters of phosphoric acid, for example dibutyl phosphate and / or monobutyl phosphate, and any desired mixtures of the aforementioned compounds.

[0058] In a preferred embodiment, the at least one acidic compound of component A2 is selected from the group consisting of alkanesulfonic acids and arylsulfonic acids, for example naphthalenemonosulfonic acid and naphthalenedisulfonic acid, toluenesulfonic acid, dodecylbenzenesulfonic acid, methanesulfonic acid, phosphoric acid and acidic esters of phosphoric acid, for example dibutyl phosphate and / or monobutyl phosphate, and any desired mixtures of the aforementioned compounds, preferably aromatic sulfonic acids, particularly preferably dodecylbenzenesulfonic acid and toluenesulfonic acid.

[0059] In a further preferred embodiment, unreacted organic isocyanate is removed after deactivation of the catalyst system by any desired methods from the prior art, for example by (thin-film) distillation or extraction, and is preferably subsequently reused (recycled).

[0060] In general, regardless of the anion responsible for the catalytic activity and selectivity, the catalysts according to the invention comprising cyclic segments are significantly more stable in the organic isocyanates to be reacted than the open-chain derivatives known from the literature from the prior art. Although this can lead to disadvantages in industrial implementation due to low solubility and turbidity formation of the catalyst's subsequent products in polyisocyanates, it also offers advantages due to the lower contamination of the recycled monomers by the N-containing cleavage products produced by cationic decomposition.

[0061] In a special continuously operated embodiment of the process according to the invention, the oligomerization can be carried out continuously, for example in a tubular reactor.

[0062] The modification process according to the invention generally makes it possible to obtain a wide range of modified isocyanates which are of high quality and are therefore very valuable for the polyurethane sector. Another subject of the present invention is the modified isocyanates obtainable or prepared by the process according to the invention.

[0063] Depending on the starting (di)isocyanates used and the reaction conditions, the process according to the invention provides polyisocyanates of the so-called isocyanate trimer type (i.e. containing isocyanurate and / or iminooxadiazinedione structures) with a low proportion of uretdione groups ("isocyanate dimers"). The proportion of the latter in the process product generally increases with increasing reaction temperature.

[0064] Preference is given to polyisocyanates having a high iminooxadiazinedione content, which can be obtained according to the invention by polyfluoride catalysis. The term "high iminooxadiazinedione content" is understood to mean at least 30 mol %, preferably >35 mol % and particularly preferably >40 mol %, based on the sum of isocyanurate and iminooxadiazinedione groups. The aforementioned molar ratios can be determined, for example, by NMR spectroscopy (see Examples).

[0065] The products or product mixtures obtainable by the method according to the invention are therefore starting materials for the production of (one or more) optionally foamed plastics and paints, coating compositions, adhesives and additives that can be used in a variety of ways. Therefore, another subject of the present invention is the use of the modified isocyanates according to the invention for the preparation of foamed or unfoamed plastics and paints, coating compositions, adhesives and additives. Therefore, another subject of the present invention is a polyurethane object that can be obtained or prepared thereby 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. When it comes to foamed polyurethane objects, PIR foams are preferred.

[0066] The process products according to the invention can be used as such or in combination with other prior art isocyanate derivatives, for example polyisocyanates containing uretdione, biuret, allophanate, isocyanurate and / or urethane groups, the free NCO groups of which are optionally deactivated with blocking agents.

[0067] The present invention further provides a one-component or two-component system comprising component A) comprising at least one modified isocyanate according to the invention and component B) comprising at least one NCO-reactive compound, as well as a coating obtainable by curing the one-component or two-component system according to the invention, optionally under the action of heat and / or in the presence of a catalyst, or produced therefrom, and a substrate coated with at least one one-component or two-component system according to the invention, optionally curing under the action of heat.

[0068] The surprising observation that the modified isocyanates according to the invention exhibit no delayed haze indicates that the products according to the invention must differ from the prior art in their structure and composition. The modified isocyanates according to the invention differ in the ratio of cations (from component A1) to anions (from components A2 and A3), more specifically in the ratio of cations (from I) to halides, preferably the ratio of cations (from A1) to chlorides and / or the ratio of cations (from A1) to bromides, as well as the ratio of cations (from A1) to sulfonate anions (from A2 and / or A3). In particular, the ratio of cations (from A1) to anions (from A2 and / or A3), wherein the anions from A2 and / or A3 contain phosphorus and / or sulfur, preferably sulfur. These differences are reflected in the cured or foamed polyurethane articles, and thus composite assemblies comprising materials at least partially bonded to the polyurethane articles according to the invention or the coatings according to the invention are also subject of the present invention.

[0069] In this context, the term "modified isocyanate" has the meaning defined at the outset and preferably refers to a polyisocyanate having a statistical average of at least 1.5 NCO groups. The modified isocyanates according to the invention are synonymous with modified isocyanate compositions, since, for example, they contain cations and anions inseparable.

[0070] The present invention particularly relates to the following embodiments:

[0071] In a first embodiment, the present invention relates to a process for preparing modified isocyanates, wherein at least one organic diisocyanate and / or triisocyanate is reacted in the at least temporary presence of a component A1 comprising at least one tetramethylammonium salt and / or at least one cyclic ammonium salt having a cation of formula I,

[0072]

[0073] in

[0074] Y is a straight or branched C2-C1-4-oxo-1 ... 20 chain segment, and

[0075] Substituent R on N 1 and R 2 independently of one another represent identical or different, substituted or unsubstituted, optionally branched aliphatic C1-C 20 Group, aromatic C6-C 20 Group or aromatic aliphatic C7-C 20 group, or

[0076] Substituent R on N 1 and R 2together form a ring segment X, for which the same or different definitions as mentioned above for Y apply,

[0077] upon reaching a predeterminable degree of conversion, based on the total amount of NCO groups of the at least one organic diisocyanate and / or triisocyanate, by adding a substoichiometric amount of component A2, based on the molar amount of cations of the formula I in component A1, comprising at least one acidic compound having a pKa value of less than 4.0 and different from HF,

[0078] And to the modified isocyanate obtained (after optional purification) is added component A3 comprising at least one acidic compound having a pKa value below 4.0 and different from HF, wherein the at least one acidic compound in components A2 and A3 can be different from or identical to each other.

[0079] In a second embodiment, the present invention relates to a process for preparing modified isocyanates according to embodiment 1, characterized in that R in the cation of formula I 1 and R 2 R represents independently the same or different C1-C8 alkyl substituents or the same or different benzyl groups optionally substituted at the aromatic ring, preferably the same or different C1-C6 alkyl substituents, particularly preferably the same or different C1-C6 alkyl substituents having a linear structure, very particularly preferably a methyl group, or 1 and R 2 Together with the charged nitrogen atom, it represents a ring segment X which is identical to or different from Y, wherein X is a C4-C6 alkylene segment which optionally carries further substituents and may optionally carry further substituents.

[0080] In a third embodiment, the present invention relates to a process for preparing modified isocyanates according to embodiment 1 or 2, characterized in that Y in the cation of formula I represents an alkylene segment which, together with the charged nitrogen atom, comprises four to seven members and optionally carries further substituents, preferably the segment Y and / or the cyclic segment X has a linear structure.

[0081] In a fourth embodiment, the invention relates to a process for preparing modified isocyanates according to any of the preceding embodiments, characterized in that component A1 contains anions selected from the group consisting of hydroxide, alkanoate, carboxylate, heterocycles having at least one negatively charged nitrogen atom in the ring, fluoride, hydrogen difluoride, higher polyfluorides, adducts of more than one equivalent of HF with compounds containing fluoride ions, and any desired mixtures thereof.

[0082] In a fifth embodiment, the present invention relates to a process for preparing modified isocyanates according to any of the preceding embodiments, characterized in that the at least one acidic compound in components A1 and / or A2 has a pKa value of less than 2.0.

[0083] In a sixth embodiment, the invention relates to a process for preparing modified isocyanates according to any of the preceding embodiments, characterized in that component A3 (stabilizer) is added together with component A2 (terminator) in a stoichiometric, preferably superstoichiometric, molar amount, based on the amount of cations of the formula I in component A1.

[0084] In a seventh embodiment, the present invention relates to a process for preparing modified isocyanates according to any of the preceding embodiments, characterized in that the at least one acidic compound of component A2 and / or A3 is selected from alkanesulfonic acids and arylsulfonic acids, for example naphthalenemonosulfonic acid and naphthalenedisulfonic acid, toluenesulfonic acid, dodecylbenzenesulfonic acid, methanesulfonic acid, phosphoric acid and acidic esters of phosphoric acid, for example dibutyl phosphate and / or monobutyl phosphate, and any desired mixtures of the aforementioned compounds, preferably aromatic sulfonic acids, particularly preferably dodecylbenzenesulfonic acid and toluenesulfonic acid.

[0085] In an eighth embodiment, the present invention relates to a process for preparing modified isocyanates according to any of the preceding embodiments, characterized in that the organic diisocyanate is selected from PDI, HDI, MPDI, TMDI, NTI, IPDI, IMCI, XDI, H6XDI, MDI, TDI or NBDI, preferably from pentamethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 1,3- and 1,4-bis(isocyanatomethyl)cyclohexane and / or norbornane diisocyanate.

[0086] In a ninth embodiment, the present invention relates to a catalyst kit for isocyanate modification comprising three components A1, A2 and A3, wherein

[0087] a) component A1 contains at least one tetramethylammonium salt and / or at least one cyclic ammonium salt having a cation of formula I,

[0088]

[0089] in

[0090] Y is a straight or branched C2-C1-4-oxo-1 ... 20 chain segment, and

[0091] Substituent R on N 1 and R 2 independently of one another represent identical or different, substituted or unsubstituted, optionally branched aliphatic C1-C 20 Group, aromatic C6-C 20 Group or aromatic aliphatic C7-C 20 group, or

[0092] Substituent R on N 1 and R 2 together form a ring segment X, for which the same or different definitions as mentioned above for Y apply,

[0093] b) component A2 comprises or consists of at least one acidic compound having a pKa value of less than 4.0 and different from HF and is used in a substoichiometric amount, based on the molar amount of the cation of the formula I in component A1;

[0094] c) Component A3 contains at least one acidic compound having a pKa value below 4.0 and different from HF, wherein the at least one acidic compound in components A2 and A3 can be different from or identical to one another.

[0095] In a tenth embodiment, the present invention relates to a catalyst kit for isocyanate modification according to embodiment nine, characterized in that R in the cation of formula I 1 and R 2 Each independently represents the same or different C1-C8 alkyl substituents or the same or different benzyl groups optionally substituted at the aromatic ring, preferably the same or different C1-C6 alkyl substituents, particularly preferably the same or different C1-C6 alkyl substituents having a linear structure, or in R 1 and R 2 Together with the charged nitrogen atom, it represents a ring segment X which is identical to or different from Y, wherein X is a C4-C6 alkylene segment which optionally carries further substituents and may optionally carry further substituents.

[0096] In an eleventh embodiment, the present invention relates to a catalyst kit for isocyanate modification according to any one of embodiments nine or ten, characterized in that Y in the cation of formula I represents an alkylene segment comprising four to seven members together with the charged nitrogen atom and optionally carrying other substituents, preferably the segment Y and / or the cyclic segment X has a linear structure.

[0097] In a twelfth embodiment, the present invention relates to a catalyst kit for isocyanate modification according to any one of embodiments nine to eleven, characterized in that component A1 contains anions selected from the group consisting of hydroxide, alkanoate, carboxylate, heterocycles having at least one negatively charged nitrogen atom in the ring, fluoride, hydrogen difluoride, higher polyfluorides, adducts of more than one equivalent of HF and compounds containing fluoride ions, and any desired mixtures thereof.

[0098] In a thirteenth embodiment, the present invention relates to a catalyst kit for isocyanate modification according to any one of embodiments nine to twelve, characterized in that the at least one acidic compound in component A1 and / or A2 has a pKa value below 2.0.

[0099] In a fourteenth embodiment, the present invention relates to a catalyst kit for isocyanate modification according to any one of embodiments nine to thirteen, characterized in that component A3 (stabilizer) is added in a stoichiometric, preferably superstoichiometric, molar amount together with component A2 (terminator), based on the amount of cation of formula I in component A1.

[0100] In a fifteenth embodiment, the present invention relates to a catalyst kit for isocyanate modification according to any one of embodiments nine to fourteen, characterized in that the at least one acidic compound of component A2 and / or A3 is selected from alkanesulfonic acids and arylsulfonic acids, for example naphthalenemonosulfonic acid and naphthalenedisulfonic acid, toluenesulfonic acid, dodecylbenzenesulfonic acid, methanesulfonic acid, phosphoric acid and acidic esters of phosphoric acid, for example dibutyl phosphate and / or monobutyl phosphate, and any desired mixtures of the aforementioned compounds, preferably aromatic sulfonic acids, particularly preferably dodecylbenzenesulfonic acid and toluenesulfonic acid.

[0101] In a sixteenth embodiment, the present invention relates to the use of the catalyst kit according to at least any one of embodiments nine to fifteen in isocyanate modification for preventing turbidity in modified isocyanates.

[0102] In a seventeenth embodiment, the present invention relates to a modified isocyanate, which can be obtained by or prepared by the method according to any one of embodiments one to eight, preferably directly obtainable.

[0103] In an eighteenth embodiment, the present invention relates to a one-component system containing the modified isocyanate according to the seventeenth embodiment in which the NCO groups are blocked, or a two-component system comprising component 1) comprising at least one modified isocyanate according to the seventeenth embodiment and component 2) comprising at least one compound reactive toward NCO groups.

[0104] In a nineteenth embodiment, the present invention relates to a coating obtainable or produced by applying the one-component or two-component system according to the eighteenth embodiment to a substrate and curing it, optionally under the action of heat and / or in the presence of a catalyst.

[0105] In a twentieth embodiment, the present invention is directed to a composite assembly comprising a material at least partially bonded to a coating according to the nineteenth embodiment.

[0106] The following comparative examples and embodiments are intended to further illustrate the present invention, but are not intended to limit the present invention. Example:

[0107] Unless otherwise indicated, all percentages are understood to refer to percentages by weight.

[0108] The mol% data are determined by NMR spectroscopy and, unless otherwise stated, are always based on the sum of the NCO conversion products. The measurements are carried out on a DPX400 or DRX 700 instrument from Bruker at 400 or 700 MHz ( 1 H NMR) or 100 or 176 MHz ( 13 The frequency of C NMR) in dry C6D6 is about 5% ( 1 H NMR) or about 50% ( 13 C NMR) was performed on samples. The reference for the ppm scale was a 1 H NMR chemical shifts of small amounts of tetramethylsilane in the solvent. Alternatively, C6D5H contained in the solvent is used as a reference signal: 1 H-NMR chemical shift 7.15 ppm, 13 C-NMR chemical shift 128.02 ppm. The chemical shift data of the relevant compounds were taken from the literature (see D. Wendisch, H. Reiff and D. Dieterich, Die Angewandte Makromolekulare Chemie 141, 1986, 173-183 and the literature cited therein, and EP 896009A1).

[0109] The dynamic viscosity was determined at 23°C using a VT 550 viscometer from Haake in accordance with DIN EN ISO 3219:1994-10. Measurements at different shear rates ensured that the flow behavior of the polyisocyanate mixtures according to the invention and the comparative products corresponded to that of an ideal Newtonian liquid. Therefore, the specification of the shear rate can be omitted.

[0110] The NCO content is determined by titration in accordance with DIN EN ISO 11909:2007-05.

[0111] The residual monomer content is determined by gas chromatography in accordance with DIN EN ISO 10283:2007-11 using an internal standard.

[0112] Unless otherwise stated, all reactions were carried out under nitrogen atmosphere.

[0113] The diisocyanates used were products of Covestro AG, D-51365 Leverkusen; all other commercial chemicals were from Aldrich, D-82018 Taufkirchen.

[0114] Reactants that were not commercially available were obtained by methods known from the literature.

[0115] Example 1: Catalyst preparation (not of the present invention)

[0116] In a 2-liter four-necked flask equipped with a stirrer and a powerful cooler, 61.7 g (1.1 mol) of KOH, 500 ml of water (deionized) and 139.7 g (1.1 mol) of 1,4-dichlorobutane were initially charged together and heated to an oil bath temperature of about 100-110° C. (mild reflux) with stirring.

[0117] After the above internal temperature has been reached, 85.2 g (1 mol) of piperidine are added rapidly enough to avoid vigorous reflux.

[0118] Solid separation occurred shortly after the piperidine addition began. The reaction mixture was heterogeneous from the outset (initially liquid-liquid, then liquid-liquid-solid, then solid-liquid), but always contained sufficient liquid phase to effectively mix most of the reaction mixture.

[0119] After the addition of piperidine was complete, stirring was continued for a further 2 hours at an oil bath temperature of 110-120° C. During this time the reflux decreased significantly.

[0120] Approximately 150 g of methanol are then metered into the still hot mixture and boiled under reflux until a finely dispersed suspension is formed. The mixture is subsequently cooled to approximately 40° C. and approximately 87 g (1.5 mol) of solid KF are metered in, with sufficient methanol (250-300 g, exact amount, noncritical) added to ensure good stirrability.

[0121] The previously filtered liquid phase was subsequently stirred at 40° C. with occasional argentometric chloride monitoring and then filtered. The filter residue was subjected to batch washing with a total of approximately 400 g of 2-ethylhexanol (2-EH) preheated to approximately 40-50° C., and 50 g of a 40% aqueous hydrofluoric acid solution (1 molar HF) were added to the combined filtrates with stirring and cooling so that the internal temperature did not exceed 40° C.

[0122] Once the HF addition was complete, the mixture was heated to reflux for 1 hour and then switched to distillate removal. After no further distillate was discharged at standard pressure and a bath temperature of 100°C, the pressure was gradually reduced to 50 mbar, the bottom temperature was gradually increased to a maximum of 150°C, and the resulting distillate was discontinuously discharged. Finally, anhydrous distillate (2-EH) was obtained overhead.

[0123] After cooling, 2-EH was added to establish the target concentration (20%), and a small amount of insoluble components was removed by filtration. The total fluoride content of this transparent, pale yellow solution (ion-sensitive electrode; where F from HF and fluoride from halogen exchange were detected as total fluoride) was 4.3%. The F from HF addition was titrated with 0.1N NaOH using phenolphthalein (as H from HF). + ) and was determined to be 2.1%, and the residual chloride content (determined by argentometric method) was 0.15%.

[0124] The other catalysts listed in Table 1 were synthesized accordingly from the initially formed chlorides by anion exchange (optionally followed by addition of HF to synthesize di / polyfluorides). Monocyclic ammonium salts 5-7 were synthesized based on commercially available N,N-dimethylammonium chloride (also shown above) by anion exchange (optionally followed by addition of HF to synthesize di / polyfluorides).

[0125] Table 1: Overview of the prepared catalysts (catalyst concentrations refer to active components (cations and anions))

[0126]

[0127]

[0128] Example series 2: Not the present invention, according to the method described in Example series 2-1 to 2-4 of EP 3107948 and Example series 2-5 to 2-7 of EP 3337836

[0129] The optimal catalyst concentration for the diisocyanate trimerization was determined in exploratory preliminary experiments at 60° C., and the concentration of the catalyst solution was adjusted by dilution with 2-EH so that no or only negligible gel particle formation was observed when the catalyst solution was added to the stirred HDI. A series of tests with distillate recycle on a 1 kg scale was subsequently carried out as described below.

[0130] A double-walled, flanged vessel, thermostated to the desired starting temperature using an external circuit and equipped with a stirrer, a reflux condenser connected to an inert gas system (nitrogen / vacuum), and a thermometer, was initially charged with 1000 g of HDI and freed from dissolved gases by stirring under vacuum (<1 mbar) for 1 hour. After filling with nitrogen, the catalyst types and amounts specified in Table 2 were metered in at the concentrations listed therein, such that the reaction could proceed in a temperature range of approximately 60 to 65° C. After approximately 1 mol of NCO groups had been converted (indicated by an NCO content of approximately 45.8%), the catalyst was deactivated by adding the terminators specified in Table 2 in an amount equivalent to the catalyst, stirring was continued for a further 30 minutes at reaction temperature, and subsequently worked up.

[0131] The workup was carried out by vacuum distillation in a thin-film evaporator of the flash evaporator (KWV) type with an upstream pre-evaporator (VV) (distillation data: pressure: 0.08+ / -0.04 mbar, VV temperature: 120° C., HV temperature: 140° C.), wherein unconverted monomers were separated as distillate and a low-monomer polyisocyanate resin was separated as a bottom product (starting run). The polyisocyanate resin was separated, the distillate was collected in a second flange-connected stirred apparatus of identical construction to the first apparatus, and the starting amount (1000 g) was made up with freshly degassed HDI. Subsequently, catalysis was resumed and the process was carried out as described at the beginning. This operation was repeated several times (tests A, B, C, etc.). After the multiple recycle steps, it was observed that the amount of catalyst required to achieve the desired conversion was initially slightly higher for the first test of each series than for the subsequent tests, but then gradually increased. Furthermore, especially for the products of the "later" recycling step (tests D and below), and usually only after a few weeks of storage and / or after the addition of typical coating solvents such as xylene or solvent naphtha, a slow onset of turbidity is observed for the polyisocyanate resins, occasionally accompanied by a slow increase in the residual monomer content, especially during storage at elevated temperatures. The precipitate obtained after filtration, as determined by a combined analytical method, proved to consist essentially of ammonium chloride (approximately 2 / 3 by mole) and bromide of the catalyst used (approximately 1 / 3 by mole).

[0132] The results are obvious from Table 2.

[0133] Table 2: Isocyanate modification performed (comparative example)

[0134]

[0135]

[0136] *) Terminator: 1: di-n-butyl phosphate, 2: toluenesulfonic acid, 40% in 2-PrOH, 3: dodecylbenzenesulfonic acid, 70% in 2-PrOH

[0137] Example series 3: According to the present invention

[0138] The process was as specified in Example Series 2, except that after reaching the target NCO content (approximately 45.8%), the catalyst was deactivated by adding a substoichiometric amount of the terminator specified in Table 3 relative to the catalyst (40-60 mol % based on the catalyst used), stirring at the reaction temperature for a further 30 minutes to ensure effective suppression of the reaction, and then working up as specified in Example Series 2.

[0139] The polyisocyanate resin separated after each cycle was isolated and subsequently post-stabilized by stirring at 60°C for one hour after the addition of stabilizer, using an amount equal to 110% of the final stoichiometric amount of the catalyst used. Even after multiple cycles, no increase in the amount of catalyst required to achieve the target conversion was observed in the respective subsequent tests. Furthermore, under the conditions described in Comparative Example Series 2, the products obtained showed no delayed onset of polyisocyanate resin turbidity or an increase in the residual monomer content.

[0140] The results are clear from Table 3.

[0141] Table 3: Isocyanate modification performed (according to examples of the present invention)

[0142]

[0143]

[0144] *) Terminator / stabilizer: 1: di-n-butyl phosphate, 2: toluenesulfonic acid, 40% in 2-PrOH, 3: dodecylbenzenesulfonic acid, 70% in 2-PrOH

[0145] Example series 4: According to the present invention

[0146] The process was as specified in Example series 3, except that PDI (1,5-pentamethylene diisocyanate) was used instead of HDI and, after reaching the target NCO content (54.9-55.1%), the catalyst was deactivated as described in Example series 3 by adding the terminator specified in Table 4 in a substoichiometric amount relative to the catalyst (40-60 mol % based on the catalyst used), stirred at the reaction temperature for a further 30 minutes to ensure effective suppression of the reaction, followed by work-up as specified in Example series 2 or 3.

[0147] The polyisocyanate resin separated after each cycle was isolated and subsequently post-stabilized by stirring at 60°C for one hour after the addition of stabilizer, using an amount equal to 110% of the final stoichiometric amount of the catalyst used. Even after multiple cycles, no increase in the amount of catalyst required to achieve the target conversion was observed in the respective subsequent tests. Furthermore, under the conditions described in Comparative Example Series 2, the products obtained showed no delayed onset of polyisocyanate resin turbidity or an increase in the residual monomer content.

[0148] The results are clear from Table 4.

[0149] Table 4: Isocyanate modification performed (according to examples of the present invention)

[0150]

[0151]

[0152] *) Terminator / stabilizer: 1: di-n-butyl phosphate, 2: toluenesulfonic acid, 40% in 2-PrOH, 3: dodecylbenzenesulfonic acid, 70% in 2-PrOH.

Claims

1. A process for preparing modified isocyanates, wherein at least one organic diisocyanate and / or triisocyanate is reacted in the at least temporary presence of a component A1 comprising at least one tetramethylammonium salt and / or at least one cyclic ammonium salt having a cation of formula I, in Y is a straight or branched C2-C1-4-oxo-1 ... 20 chain segment, and Substituent R on N 1 and R 2 independently of one another represent identical or different, substituted or unsubstituted, optionally branched aliphatic C1-C 20 Group, aromatic C6-C 20 Group or aromatic aliphatic C7-C 20 group, or Substituent R on N 1 and R 2 together form a ring segment X, for which the same or different definitions as mentioned above for Y apply, upon reaching a predeterminable degree of conversion, based on the total amount of NCO groups of the at least one organic diisocyanate and / or triisocyanate, by adding a substoichiometric amount of component A2, based on the molar amount of cations of the formula I in component A1, comprising at least one acidic compound having a pKa value of less than 4.0 and different from HF, and adding to the modified isocyanate obtained, after optional purification, a component A3 comprising at least one acidic compound having a pKa value of less than 4.0 and different from HF, The at least one acidic compound in components A2 and A3 may be different from or the same as each other.

2. The method according to claim 1, wherein R in the cation of formula I 1 and R 2 R represents independently the same or different C1-C8 alkyl substituents or the same or different benzyl groups optionally substituted at the aromatic ring, preferably the same or different C1-C6 alkyl substituents, particularly preferably the same or different C1-C6 alkyl substituents having a linear structure, very particularly preferably a methyl group, or 1 and R 2 Together with the charged nitrogen atom, it represents a ring segment X which is identical to or different from Y, wherein X is a C4-C6 alkylene segment which optionally carries further substituents and may optionally carry further substituents.

3. The method according to claim 1 or 2, wherein: Y in the cation of formula I represents an alkylene segment which, together with the charged nitrogen atom, contains four to seven members and optionally carries other substituents. Preferably, the segment Y and / or the cyclic segment X has a linear structure.

4. The method according to any one of the preceding claims, characterized in that Component A1 contains anions selected from the group consisting of hydroxide, alkanoate, carboxylate, heterocycles having at least one negatively charged nitrogen atom in the ring, fluoride, hydrogen difluoride, higher polyfluorides, adducts of more than one equivalent of HF with compounds containing fluoride ions, and any desired mixtures thereof.

5. The method according to any one of the preceding claims, characterized in that The at least one acidic compound in components A1 and / or A2 has a pKa value of less than 2.

0.

6. A method according to any one of the preceding claims, characterised in that Component A3 (stabilizer) is added together with component A2 (terminator) in a stoichiometric, preferably superstoichiometric, molar amount, based on the amount of cation of the formula I in component A1.

7. A method according to any one of the preceding claims, characterised in that The at least one acidic compound of component A2 and / or A3 is selected from the group consisting of alkanesulfonic acids and arylsulfonic acids, for example naphthalenemonosulfonic acid and naphthalenedisulfonic acid, toluenesulfonic acid, dodecylbenzenesulfonic acid, methanesulfonic acid, phosphoric acid and acidic esters of phosphoric acid, for example dibutyl phosphate and / or monobutyl phosphate, and any desired mixtures of the aforementioned compounds, preferably aromatic sulfonic acids, particularly preferably dodecylbenzenesulfonic acid and toluenesulfonic acid.

8. The method according to any one of the preceding claims, characterized in that The organic diisocyanate is selected from PDI, HDI, MPDI, TMDI, NTI, IPDI, IMCI, XDI, H6XDI, MDI, TDI or NBDI, preferably selected from pentamethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 1,3- and 1,4-bis(isocyanatomethyl)cyclohexane and / or norbornane diisocyanate.

9. A catalyst kit for isocyanate modification comprising three separate components A1, A2 and A3, wherein a) component A1 contains at least one tetramethylammonium salt and / or at least one cyclic ammonium salt having a cation of formula I, in Y is a straight or branched C2-C1-4-oxo-1 ... 20 chain segment, and Substituent R on N 1 and R 2 independently of one another represent identical or different, substituted or unsubstituted, optionally branched aliphatic C1-C 20 Group, aromatic C6-C 20 Group or aromatic aliphatic C7-C 20 group, or Substituent R on N 1 and R 2 together form a ring segment X, for which the same or different definitions as mentioned above for Y apply, b) component A2 is used in a substoichiometric amount, based on the molar amount of the cation of the formula I in component A1, and comprises or consists of at least one acidic compound having a pKa value of less than 4.0 and different from HF; c) component A3 contains at least one acidic compound having a pKa value below 4.0 and different from HF, and The at least one acidic compound in components A2 and A3 may be different from or the same as each other.

10. The catalyst kit according to claim 9, characterized in that The at least one acidic compound of component A2 and / or A3 is selected from the group consisting of alkanesulfonic acids and arylsulfonic acids, for example naphthalenemonosulfonic acid and naphthalenedisulfonic acid, toluenesulfonic acid, dodecylbenzenesulfonic acid, methanesulfonic acid, phosphoric acid and acidic esters of phosphoric acid, for example dibutyl phosphate and / or monobutyl phosphate, and any desired mixtures of the aforementioned compounds, preferably aromatic sulfonic acids, particularly preferably dodecylbenzenesulfonic acid and toluenesulfonic acid.

11. Use of a catalyst kit according to at least claim 9 or 10 in isocyanate modification for preventing turbidity in modified isocyanates.

12. Modified isocyanate obtainable by or prepared by the process according to any one of claims 1 to 8, preferably directly obtainable.

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 toward NCO groups.

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

15. A composite component comprising a material at least partially bonded to a coating as claimed in claim 14.

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